Board
lissencephaly
"Smooth brain"; condition where there is little to no gyri or sulci within cerebral cortex, migration issue
anterolateral impingement syndrome
"Synovial hypertrophy or scarring in lateral ankle gutter. Space between tibia and fibula bound by lateral ankle ligaments. Lateral ankle pain and inability to dorsiflex normally. usually secondary to chronic injury of the anterior talofibular and tibiofibular ligaments from recurrent ankle sprains, just get scarring (low T1/T2) in the lateral gutter area.
CMV in AIDS
- brain atrophy -ependymal cell enhancement
T2 dark renal cyst DDx (3)
- lipid poor AML - hemorrhagic cyst - papillary subtype RCC
Carney complex
-Autosomal dominant conditions comprising myxomas(low t1/hight2) of the heart and skin, hyperpigmentation of the skin (lentiginosis), and endocrine overactivity. It is distinct from Carney's triad (pulmonary chordoma, extra adrenal pheo, GIST). Approximately 7% of all cardiac myxomas are associated with Carney complex. -Cardiac myxomas occur anywhere -They get calcified Sertoli cell tumors (make androgens) in testes almost 100% by adulthood. -Thyroid follicular adenomas in 75% of patients.
Osteoblastoma vs aneurysmal bone cyst
-Both tend to hit the posterior vertebral elements - obsteoblastoma tends to have calcified matrix, and also tends to have soft tissue component leading to periostitis, unlike ABC -osteoblastoma (like Giant cell) can have a secondary ABC. -expansile lesion in posterior elements, think osteoblastoma vs ABC (osteoid osteoma and hemangioma are not expansile), if it has internal matrix then its osteoblastoma (ABC doesnt have internal matrix).
HIV encephalitis
-CD4<200 -SYMMETRIC T2/FLAIR signal in white matter -T1 is normal -Sparing of subcortical U fibers
PML encephalitis
-CD4<50 -hits subcortical U fibers -asymmetric -low T1 (HIV encephalitis is normal on t1) with high T2/FLAIR signal in the subcortical areas
Moire Fringes Artifact
-Cause by interfaces of aliased signals at different phases -Most often seen in 3D gradient echo images - AKA Zebra Artifact, usually at the periphery, appear curvilinear -fixed by using smaller FOV, going to 1.5T instead of 3 Tesla, shimming to prevent inhomogeneities ,and using shorter TR.
Tc99 dtpa aerosol vs xenon
-Less radiation than xenon, no need to have collection hood, persistence of activity in the lungs which allow for multiple projections -DTPA aerosol however cannot demonstrate air trapping, and not good for patient with obstructive lung disease and tachypnic patients, leads to central deposition in these patients with tc99 DTPA (LOOK FOR COUNTS IN THE ESOPHAGUS, TRACHEA, STOMACH FROM SWALLOWED PARTICLES). -TC-DTPA will use same tech as TcMAA, so use smaller amount for DTPA before MAA. -MAA particles, about 500 for normal study, decrease if pulmonary htn, pregnant, children <5 yo should have 50-150000, and neonates 10000.
whole body radiation symptoms/issues
-Nausea (30% people) - 0.75-1.25Gy WB -Depress circulating lymphocytes (most sensitive cells to radiation )- 0.25Gy WB -LD 50/60 (marrow, 50% dead by 60days)- 3-4 Gy WB -LF 50/4 (GI, 50% dead by 4 days)- 8-10 Gy WB -LD for CNS - >20Gy WB -Double the natural or spontaneous mutation rate- 1 Gy -Effective dose from background radiation in the US- 3mSv per year
Relative contraindication to PE thrombectomy
-Right heart strain , more than 70/20 , if you have to go into the right or left pulm, not the main with elevated right heart pressures -LBBB, can get RBBB, so do transcutaneous pacer beforehand
Renogram numbers
-Time to peak activity. Normal is about 3 to 5 minutes. -Relative renal uptake ratios at 2 to 3 min- utes. This is an index of relative renal func- tion between the two kidneys. Activity in each kidney should be equal, ideally 50%. A value of 40% or less in one kidney should be considered abnormal. -Half-timeexcretionisthetimeforhalfofthe peak activity to be cleared from the kidney. Normal is about 8 to 12 minutes. -Differential cortical retention at 15 minutes. The percentage of retained activity about 15 minutes after injection in each kidney should be relatively equal. Differences of 20% or more should be considered abnormal. -The 20 minute-to-peak count ratio. This is the activity measured in each kidney at 20 minutes and expressed as a percentage of peak curve activity. As renal function deteriorates, delayed transit of the radiopharmaceutical in the kid- ney results in an abnormal renogram curve, which can be quantitated by using this index. In the absence of pelvic calyceal retention, or if only a cortical region of interest is used, a normal 20-minute maximal cortical ratio for 99mTc-MAG3 is less than 0.3 (or 30%). - Lasix T1/2 time values between 10 and 20 minutes obstruction are assigned an indeterminate for obstruction category.
hemimegalencephaly
-enlargement of all or part of one hemisphere = big side + big ventricle
radiation doses
-general public =1mSv or 100mrem -background annual dose = 3mSv or 300mrem -dose limit for a fetus= 5mSv or 500mrem (10% of worker) -total effective occupational dose limit for radiation worker= 50mSv or 5000mrem -dose limit for radiation worker lens = 150mSv -dose limit for radiation worker's extremity, skin, or any organ= 500mSv or 50000mrem 1sV=100rem, 1mSv=100mrem
Placenta chorioangioma
-hamartoma -most common benign tumor of placenta -hypoechoic mass near cord insertion -pulsating Doppler flow -can cause hydrops if big and multiple, if more than 4cm (platelet sequestration and CHF -hydrops)
MELAS
-lactic acidosis, lactate peak, NAA decreased -affects grey matter (unlike leukodystorphies which affect white matter symmetrically, bc the grey has more mitochondria) (need more oxygen).
piriform aperture stenosis
-narrow bony nose inlet -associated with hypothalmic-pituitary-adrenal axis dysfunction
degenerative and inflammatory msk diseases
-no bony proliferation and prox distribution-RA -multiple joints with bony proliferations, distal invovlement more-as, Psoriasis, Reactive arthritis, IBD.
Salpingitis isthmica nodosa
-nodular scarring of fallopian tubes -causes infertility and ectopic pregnancy -involves the distal Fallopian tubes (the isthmus)
Abdominal Compartment Syndrome (ACS)
-presence of sustained IAP > 20 mm Hg, with or without abdominal perfusion pressure (APP = MAP - IAP) <60 mm Hg, and associated new organ system dysfunction or failure. -life-threatening complication that mandates immediate decompression by laparotomy; otherwise, multiple organ dysfunction and death quickly ensue. Percutaneous drainage of peritoneal fluid may precede formal laparotomy, as long as the patient is monitored closely and laparotomy is immediately instituted if the patient continues to deteriorate. -willl see mass effect from ascites and hemorrhage on the organs.
Joubert syndrome and associations
-small/aplastic cerebellar vermis -"Molar tooth" superior cerebellar peduncles issue -bat like appearance of the fourth ventricle -associated with retinal dysplasia (50%) and dysplastic kidneys (30%)
Pulsed fluoroscopy
-x-ray exposure is not continuous and has gaps of no exposure -decreased patient dose if less than 30 frame/sec
Pediatric mAs does
0-5- use 25% of the mAs that an adult would get 6-12- use 50% of the mAs that an adult would get
What's maximum concentration of eluate of moly 99 when making Tech 99
0.15 microcurie of Moly-99 per millicurie of Tech 99
Radionuclide purity test
0.15micro Ci of Mo in 1milli Ci of Tc, at the time of administration
maximum Mo in Tc-99
0.15microCi per mCi of Tc-99
Standard dose of gadolinium for breast MRI
0.1mmol/kg followed by 10mL saline flush.
How much gadolinium for cardiac mri
0.2mmol/kg
Attenuation of sound
0.5dB x full travel path in cm x TF in MHz
Attenuation
0.5dB/cm/MHz I.e. how much attenuation for a feature at 4cm depth and 10mHz transducer. The round trip=8cm Attenuation= 0.5db/cm/Hz x (8cm) x (10Mhz)= 40dB.
Max magnetic strength for cardiac pacemaker
0.5mT
Occupational dose limit for entirety of a fetus
0.5rem (5mSv), 10% of adult dose
Average dose received by a person in the US
0.6rem (6 mSv)
Whole body MRI should not increase by how much in adults and in pediatrics?
1 Celsius in adults, 0.5 Celsius in kids
ACR Appropriateness criteria for liver transplant
1 tumor less than 5cm, or up to 3 tumors less than 3cm each Ablation is curative, just like surgery, TACE and RFA are palliative or to allow other curative txs.
Typical radiographic, fluoroscopic, and interventional doses
1-10 in radiograph (mGy), 20-50 in fluoroscopy (mGy), and 100s (300mGy) in IR
Iodine
1-123- 13 hr half life, 159kev , (electron capture), I-131- 8 day half life, 365kev (beta emitter) Technetium is also taken up, but not organized, can use when recent iodine given (i.e. contrast, or iodine blocking agents). Give either 5microC of 131 or 10-20 microC of 123. 4 hr and 24 hr uptake, 4 hr 5-15%, 24 hr 10-35% Toxic must nodular goiter vs graves: Gland in graves is diffusely hot, graves uptake is around 70% Galen in multinodular goiter is going to be hot but uptake in the 40-50% Subacute thyroiditis (quervains)= high t3/t4, low tsh (like graves) but decreased iodine uptake. I131 Tx 100 to thyroid only, 150 thyroid plus nodule, 200 for systemic mets After surgery you measure thyroid levels, if <5% you can treat, if more they should go back to or bc tx will hurt. Dose for grave's —> 15mCi, dose for multinodular goiter—> 30mCi (less vascular , so need more drug to reach it compared to graves) When to take to hospital after I-131tx; More than u7mR/hr 1 m away, or 33mCi I 131 residual activity. Side effects iodine: Pulmonary fibrosis if there are mets there. Sjorgens pfts have greater risk of injury to salivary glands with iodine therapy. If you participate in therapy, need thyroid checked at 24hrs. Absolute contraindications: pregnancy, severe uncontrolled thyrotoxicosis. If you see uptake in the liver on I131-its post treatment related. TSH level needed prior to ablation therapy=>30, preferred 50. If cant attain it, rhTSH (Thyrogen) given intramuscularly 48 and 24 hrs before RIAT. Thyrogen stimlated Tg levels of TSH less than 2 is reassuring for absence of recurrence. Incidental noted FDG PET uptake in thyroid gland has 33% malignancy Cold nodule has 10-20% chance of malignancy
Pleuropulmonary blastoma
1-2 y/o, big ****ing chest tumors, no rib erosion (like Atkins aka Ewing's) and no calcifications. Atkins' aka Ewing's is usually 10+ yo
Post lung cancer radiation changes
1-3 months= patchy opacities >3 months= fibrosis, bronchiectasis , volume loss
Correct dose of epinephrine in iodinated contrast reaction
1-3ml of 1/10,000 dilution IV or 0.3mL of 1/1,000 dilution IM.
Avg current and voltage on fluoroscopy
1-5 mA, 70-100 KVP Flat panel detectors and II have similar radiation doses
AAST renal injury grading
1-renal contusion, onexpanding subcapsular hematoma 2- nonexpanding hematoma in perirenal space or a <1cm renal lac without collecting system injury 3->1cm lac without collecting system injury 4->renal lac involving collecting system, or main renal art/vein resulting in urine leak, or involvement of the renal vessels. 5-> shattered kidney or avulsion of renal hilum and lack of flow of the renal artery
Peripartum cardiomyopathy
1. Antibodies made against myocardium in pregnant women 2. LV dysfunction reversible, short term 3. If LV dysfunction does not improve - undergo cardiac trasnplatnation 4. Medical therapy : ACEi, ARB, BB, spironolctone, diurteics, digoxin 4. Repeat pregnancy in woman wiht periaprtum cardiomypatohy wil provoke enormous antibody production agaisnt myocardium - subepicardial non vascular territory enhancement
Most common whipple's complications
1. Delayed gastric emptying (> 1 day need for ng tube) 2. Pancreatic fistula (50 ml amylase through drain >7-10 days ) 3. Infection (3rd most common)
FOV, frame rate and spatial resolution in ultrasound parameters and changes
1. Increased scan lines= decreased frame rate, increased spatial resolution (lateral), doesn't change FOV. 2. PRP increased= more time btw pulses, increased FOV but decrease spatial resolution (the scan lines diverge more).
RCC staging
1. Kidney < 7 cm 2. Kidney > 7 cm 3. Inside gerota's fascia: - a) Renal vein invaded - b) IVC below diaphragm - c) IVC above diaphragm 4. Beyond Gerota's fascia; Ipsilateral adrenal Clear cell-VHL, papillary- hereditary papillary renal carcinoma, chromophobe-birt-hugg dube, medullary-sickle cell trait Wont do RFA if < 1.5cm
wilms tumor staging
1. limited to kidney + complete excision w/o rupture 2. tumor extends locally but can still be excised, hits the renal vein here. 3. residual tumor remains in abdomen, or spillage during resection, aat this stage goes to lungs or liver. 4. bilateral renal involvement Stage 1 tx is nephrectomy and then chemo for 2 yrs
Resolution in cardiac mri
1.2x1.5mm , can see endo,myo,and epicardium
size of LUNG tumor you can do RFA
1.5-5cm
resolution in direct and indirect FPD fluoro
1/ 2 x pitch (pitch is distance between beginning of 2 DELs)
Epinephrine for anaphylaxis doses
1/10000 for IV (1-3cc) 1:1000 for IM (1-3cc)
Effective half life formula
1/effective half life= 1/physical half life + 1/ biological half life The total rate of emissions coming from the patient decays (effective half life) bc the radiopharmaceutical decays (physical half life) and bc the drug is excreted (biological half life).
Maximum concentration of aluminum ions per technetium generator elluate
10 micrograms of aluminum per ml of technetium 99 solution (10 ppm of alluminum ion) if more, then you can have aluminum breakthrough, resulting in free Tech-mixing with aluminum, creating tech-sulfur colloid which will show liver/spleen uptake on things like tc-mdp bone scan.
If no additional mammograms are ever done on a one time patient, until when should they hold on to the study
10 years! If they come back and get additional testing then you have to hold on to the last study at least 5 years.
NRC-mandated annual dose for < 18 y/o
10% of adult, so 0.5rem (5mSv) compared to adult yearly which is 5rem(50mSev)
NRC (Nuclear Regulatory Commission) requires dose measurements if you receive what % of allowed per year?
10% or 0.5rem (5mSV) which is 10% of the 5rem (50mSV) allowed per year.
NRC requires you wear dose monitor when you exceed how much of annual dose , for radiation worker?
10%, since annula is 50mSv, then after 5mSv must wear badge, for extremity since its 500mSv after 50 mSv must wear badge or ring.
Sentinel node
10-50nm Tc99 sulfur colloid Particles less than 100nm to make study quick.
Thrombin dose for pseudoaneurysm
100-1000 IU
Major spills criteria
100mCi of Tc99m 100mCi of Tl-201 10mCi of Ga-67, In-111, I-123 1mCi of I-131
Dose rate entrance skin exposure limit for fluoroscopy
10R or 100mGy Boost mode for fat patients 20R or 200mGy
Breast compression force
111-200 Newtons (25-45lbs).
maximum air pressure during barium enema
120mmHg
mammo required line pairs
13 lp/mm in anode to cathode direction, 11lp/mm in the right-left direction
Wedge pressure
13-18= cephalization, prominent vascular pedicure 18-25= interstitial edema >25= alveolar edema
PET myocardial agents
13-Ammnoia, and rubidium 18 , ammonia is best bc it travels a shorter distance before undergoing annihilation compared to Rb-82, so better images. These 2 are used for perfusion, not viability.
FDA hearing protection for MRI
140dB for MR (99dB for patients with hearing protection).
Sentinel event threshold for the Joint commission
15 Gy
cold thyroid nodule is cancerous in what percent?
15-20% chance of malignancy
CT and MRI phase sequences
15-30 secs arterial, 70 portal, 90-5mins venous , both CT and MRI.
BHCG Levels and Pregnancy
1500-2000 gestational sac should be seen 5000 yolk sac should be seen
sentinel event by radiation dose
15Gy
CT phantom
16 and 32cm diameter, made of PMMA (acryllic)
Gage and wires
18 gage accepts a 0.038 wire, 21 gauge accepts a 0.021 wire.
DAI classification
1=grey white matter 2=corpus callosum (usually posterior) 3=brainstem
Hot sink dose limit
1Ci all year. Keep log on liquids disposed.
CC and MLO view should be how much different for adequacy
1cm
nrc requires report to workers once their dose exceeds how much?
1mSv or 0.1rem
Extensor compartments msk
1rst compartment (radial side) - APL and EPB- site of de Quervains (thickening of the sheath and enlargement of the tendons(tendinosis)). 2nd-ECRL &ECRB 3rd compartment - Lister's tubercle is medial to it, hits EPL 6th compartment - Extensor carpi ulnari - site of RA - tendon can get Tennysonivitis from it.
Skin and radiation
2 Gy -transient erythema 3-7Gy- temporary and permanent epilation 10-15Gy-dry and moist desquamation 10Gy- dermal atrophy
DEXA
2 consecutive spines to assess spine DEXA, avoid sclerotic, post op (lambs), etc. Best at the hip bone, femoral neck, best response to therapy is seen at the spine, best risk of fracture is calculated at the hip. Z score can be used for premenopausal women, men under 50 and children, score less than -2 is indicative of osteopenia.
Bucky factor
2 in mammography and 5 in general radiography Bucky decreases scatter and noise, but increases dose
typical CT scan dose
2-20mSv, abdomen CT is 25mSv.
Fetal systolic/diastolic ratio
2-3 by 32 weeks, at First its like 4, then the brain grows and you need more diastolic continuous flow, so 2-3 by 32 weeks.
Four phase bone scan
2-3 hr post blood pool. Then at 18-24 hrs post MDP administration.
Pulse in ultrasound is how many wavelengths
2-3 wavelengths long Usually due to the backing material (in the piezoelectric crystals) which reduces the wavelength and increases the bandwidth. Broad bandwidth has better axial resolution in U/S.
transient erythema in fluoroscopy
2-5Gy transient early erythema, 5-8 Gy -temporary and permanent epilation, 5-10 chronic erythema, 10-15 dry and moist desquamasation, >10Gy-skin atrophy epilation think 3x7=21 3 is transient 7 is permant, both arise around 21 days.
Aluminum shield at >70kVp
2.5mm of aluminum shield required for any diagnostic radiographic unit that exceeds 70kVP.
AVF in kidney ultrasound
2/2 biopsy, not the ying yang of pseudoaneurysm, but the tissue vibration artfiact (mosaic color assignment ) with high arterial velocity and pulsatile flow in the vein, secondary to high pressure at teh AVF.
Clay shoveler's fracture
2/2 flexion of the neck , results in C6, C7 or T1 flexion injury. Stable type of fracture. The interspinous ligaments pull on one another.
flare/veiling glare
2/2 glass window, which allows some light to bounce back and forth , creating the artifact. only seen in II
Asymmetric enlargement of the pulmonary artery
2/2 pulmonary valve stenosis , the jet preferentially hits the left pulmonary artery. Chronic PE, and primary pulmonary htn would result in bilateral pulmonary artery stenoses.
Weighted ct dose
2/3 peripheral + 1/3 central ct dose index
T1/2 half life of tracer from collecting system is indicative of obstruction after how many minutes
20 mins, if not reached 50% excretion by 20 mins, then you have obstruction. 15-20 minutes is indeterminate
Breast specific gamma imaging
20-30mCi Tc99-Sestamibi Inject in contralateral arm, then emeasure at 20 minutes Breast density doesn't affect distribution False pos-fibroadenoma, fibrocystic changes, inflammation
uptake on grave's disease
24 hour uptake 40-70%, normal should be less than 30% at 24 hrs.
Mammography certification
240 exams within 6 months of last 2 yrs of residency 960 exams per 2 years 15 category-1 CME credits per 3 years
when to begin screening mammography?
25-30 if breast radiation or 8 years after, whichever is later BRCA 1rst degree relative or BRCA carriers starting at 25-30 Pt is 1rst degree relative of someone with premenopause breast cancer, 10 yrs before relative onset or 25-30 y/o, whichever comes later.
Normal inversion time in myocardium
250-350
Avg entrance air kerma rate for fluorsocopy
25mGY/min
Deterministic skin effect dose
2Gy
threshold to drain diverticular abscess
2cm
Diagnostic radiology units operating at greater than 75kEv , how much lead shielding at least
2mm
Nuclear medicine restricted areas radiation doses
2mrem /hr or 100mrem/year is restricted, I.e. hot lab, thyroid uptake room, shipping /receiving room.
Branchial cleft cyst
2nd branchial cleft, lateral , lateral to everything! Submandibular, carotid space, anterior to sternocleidomastoid.
DATscan (I-123 ioflupane)
3 hr post administration Bilateral comma shaped striata signal is normal Isoflupane is an analog to cocaine
If a package arrives to a facility, how long does the lab have to inspect it?
3 hrs
Receiving and storage of material in nuclear medicine
3 hrs of receipt
Entrance air kerma for KUB
3 mGy
When to get PET after radiation?
3 months
how long does NRC require facility to keep written directive for administration of radiopharm?
3 years.
threshold to drain renal abscess
3-5cm
Maximal residual cortical activity for MAG3
30%, up to 30% of residual contrast should be in cortical phase at 20 mins compared to maximal cortical uptake, so normally should be less than 0.3.
I-131,when ok to release patient
30-33 mCi given max, 7mrem/hr from 1 meter away or less, potential to person hit by radiation from pt must not exceed 0.5 rem per year. max dose that pt can give to family member from iodine is 5mSv.
CT abdomen dose for fetus
30mGy, KUB 2.5mGy, CT head 0, CT sinus 0, CT chest 0.16mGy, HSG or fluoro 10mGy.
2d pet vs 3D pet
3D DOSESNT USE THE LEAD SEPTA INBETWEEN THE SCINTILLATORS AND ALLOS FOR OBLIQUE ACTIVATION OF PMT
2d vs 3D MRI
3D uses 2 phase encoding direction, in plane and thru plane. The images can then be reformatted in any plane, without loss to resolution.
Maximum specific absorption rate for MRI imaging of the head and body
3W/kg for head in >10 min study, and 4W/kg in whole body over 15 mins.
Lung cancer staging
3b= nonresectable 3b= cancer in 2 lobes on the same side (makes it t4), mets on opposite mediastinum/hilum, malignant pleural effusion, mets to supraclavicular/scalene nodes.
time limit for iv tpa and intraarterial thrombectomy
3hrs for IV TPA and 6hrs for thrombectomy
third vs fourth generation CT scanners
3rd- tube and detector move together, can get ring artifact; most common in use today. 4th-tube moves, but you have 360 degrees of detectors, prevents ring artifact.
Both type 2 and type 3 enhancement patterns should be BIRADS:
4
renal transplant ultrasound findings
4 enlarged kidney thickening of urothelium prominent renal pyramids increased RIs
Complete recovery of longitudinal magnetization in relationship to T1
4 X T1 means 100% of longitudinal magnetization has recovered. Where's after T1 about 63% has recovered. 2 x T1 about 86%.
What goes through carpal tunnel?
4 flexor dig superficial and 4 flexor dig deep tendons, 1 median nerve, 1 flexor pollicis longus
How long to wait prior to I-131 if patient received ct scan with contrast (iodine)
4 weeks, even though agents half life is typically 2 hrs, the organification of the iodine in thyroid makes it the long wait, bc this iodine will compete with the I-131 and lead to subtherapeutic dose.
Arch of Buehler
4% of cases, firect connection between the celiac (off teh common hepatic) to the SMA.
risk of radiation induced cancer
4-5% per Sv in adult, 10-15%/Sv in child.
Post menopausal endometrium size
4-5mm or more, gets a biopsy
William Campbell syndrome
4-6th branch bronchi bronchiectasis, spares the main bronchi (unlike munier Kuhn and CF, ciliary diskineasia ) and hits upper and lower lobes.
Acr phantom for breast
4.2cm thick with 50% glandular and 50% adipose tissue
Radial scar
40% of radial scars are upgraded upon removal, because of this , if biopsy comes back as radial scar, excision is recommended.
Initial imaging for gallium-67
48-72 hrs after for cancer evaluation (like lymphome, more specific for hodgkins) after 24 hrs should not be in the lungs liver (intense uptake), bone, stomach, salivary glands show normal uptake. critical organ is the colon
Limit of heating from MRI
4W/kg for whole body per 15min interval.
Normal thyroid nuclear medicine study
4hr-> 6-18% 24hrs-> 10-30% I123-13hr t1/2, 159kv I131-8day t1/2, 365kv Lactating womenwhen to resume Tc-12-24hrs I123- 2-3 days I131- pump and dump I131 tx->15mCi Graves 30mCi for multinodular goiter(they have a capsule so they need more)
minimum time for IV steroid efficacy
4hrs prior to contrast administration
How long must reportable events be kept by a facility per NCR
5 years
Dose trivia
5% per Sv-adult Up to 15% per Sv-for child 1 ct - 100 pa and laterals xrays Ct extremities has very low effective dose (<1mSv) bc they don't contain any radiosensitive organs Embryo dose in CT A&P is around 30mGy
Normal post TIPS pressure gradient
5-12mmHg
Dose calibrator
5-25mCi of dose calibrator Constancy-daily , use Cs 137 bc of long half life Linearity-quarterly, tend to use Tc Accuracy- annually, check against standard doses of 3 types of radioisotopes (Co-57, Cs-137, Co-60; which are all gamma emmiters, it's arranged from low, med to high emitters) Geometry-every time installation of machine , Tc99 , will you get same measurement regardless of the shape of the elements.
Lethal dose 50/60
50% by 60 days, occurs btw 3.5-7Gy
patient with breast cancer and rib + additional source uptake on bone scan
50% risk mets, one rib only is 1-2%
Typical dose for moderate sedation
50mcg fentanyl, 1mg midazolam
Total organ dose limit
50rem(500mSV) for an adult
Maximal dose to any extremity per year
50rem(500mSv)
Klinefelter's syndrome
50x greater chance of having nonseminomatous anterior mediastinal tumor (i.e yolk sac(afp), choriocarcinoma (bchg), embryonal carcinoma) In patients without Klinefelter's seminomas are most common tumors in anterior mediastinum (high ldh).
Gallium dose
5mCi for infection, 10mCi for cancer
Fetal dose total
5mSEV
Total dose to fetus during entire pregnancy
5mSev, 0.5mSev per month
Phenobarbital
5mg/kg/day 5 days prior to rule out false positives for biliary atresia
typical lead equivalent thickness for shielding aprons
5mm
Total dose to pregnant radiation worker in a year
5msEv with fetus, but her work total in a year is 50mSEV
NRC annual dose limit for radiation worker
5rem(50mSv)
High volume lung in neonates
6 or more anterior ribs and 8 or more posterior ribs Meconium aspiration—>ropy appearance, pneumothorax in 20-40% Transient tachypnea of the newborn—> coarse interstitial markings, peaks at 1 day, done by 3 days. Non group B strep—> look for pleural effusion.
at what time is myocardial enhancement attained?
6-45 mins, but usually at 10-12 mins post gad.
ACR phantom components
6-5-5 (fibers-speck groups-masses) Passing score requires 4-3-3 ACR phantom is equivalen to 4.2cm breast with 50% glandularity
How much does an ultrasound probe lose per cm traveled
6/frequency will give you the half value layer 12MHz transducer will have half by 6/12= 0.5cm 6MHz transducer will have half by 6/6=1cm (why lower frequency travels more)
clumped mass like enhancement on breast mri
60% chance of malignancy. 75% chance of malignany if segmental (conical in shape with apex pointing to the nipple)
breast CME crap
60h Cat 1 CME during residency, 15hr must have been obtained within 3 yr of qualifying to interpret initial experience-240 exams under direct supervision in 6 mo before interpreting, or if passed boards first time 6-mo period last 2 yrs new modality-8hr training continuing experience-960 exams/24mo continuing education- 15 cat 1 CMEs/36mo modality specific- 6 cat I CME in each mammo modality
Y-90
64 hr half life, beta emmiter, half life 11 hrs. need 2 things prior: 1)lung shunt fraction with tc99-MAA, need less than 30Gy in a single tx 2) assess take off of the right gastric (can come off proper hepatic or left hepatic) and cause gastric ulcer. so, before y-90 embolize the right gastric
Pulmonary sling is due to failure of formation of which embryological aortic arch?
6th Crosses between the trachea and esophagus, only one that does that.
why is gadolinium paramagnetic?
7 unpaired electrons in the 4F shell each unpaired electron has a magnetic moment 658x larger than that of a hydrogen proton
Resolution of PET scanners? (mm)
7-8 mm
What's DLP for low dose CT screening for lung cancer?
75mGy-cm
Post lung transplant
8 days- 2 months- acute rejection= GGO >2 months - CMV (GGO and tree in bud, never occurs before 2 weeks post transplant) >4 months- bronchiolitis obliterans (bronchiectasis, fibrosis, air trapping, >50% get it by 5 yrs), COP (can also happen in the acute phase, these respond to steroids). Air trapping on expiration seen after 6 months= bronchiolitis obliterans. Most common disease to recur after lung transplant= sarcoidosis (35%)
How long does a mammographer need on a new modality per MQSA before he can read such studies, I.e. like digital tomo
8 hr CMEs
endometrial thickness on hormone replacement therapy
8-11mm is upper limit.
Nephrographic phase
80 secs, portal is 70 seconds, late arterial 15-30 secs.
Sacrococcygea teratoma
80% benign, different types based on intrapelvis or abdominal location. Type 4 is the one totally inside abdomen, has highest rate of malignancy. Have to cut the coccyx off during resection, incomplete is associated with higher recurrence rate.
air kerma limit
87mGy/min
Automatic exposure rate control circuit limit
87mGy/min (10 R/min)
Air kerma limit
87mGy/min (10Roentgens ) High level control limit (for really fat patients) 176mGy/min (20 Roentgens per min) When using high level control limit, you must have audible or visual alarms, not just normal timers.
Maximum skin entrance for fluoroscopy
88mGy/min If patient is really fat, can do high output mode for 176mGy/min
mammographer wants to read new modality, how much training required?
8hrs of continuing medical education
maximum catheter flow rates
8ml/sec per F size after 3f. 3F=8 4F=16 5F=24cc/sec
upper limit of normal end diastolic volumes in MRI
90 in females, and 100 in males
Pediatric intussusception
90% ileocolic or ileoileocolic , usually due to Peyer's patches in the ileum. Intermittent right upper quadrant pain, can see the half doughnut sign with fat surrounding the mass. Intussuception in adults is usually bad If more than 2.4cm you can do air enema, less than 2.4cm you can watch. If sxs >24hrs, peritonitis, free air then do not do enema Recurrence rate of 30% Currant jelly stool is usually see after 24 hrs, may not need to do then
gastric emptying study
90% out by 4 hrs, 90 by 4. tc sulfur colloid w/ food; critical organ is colon. anterior and posterior counts are taken with geometric means of counts.
Wilms tumor metastasis
90% to the lung (stage 3) (stage 4 is contralateral kidney) Wilms is a cortically based neoplasm, whereas mesoblastic nephroma and rhabdoid sarcoma are from the medulla, so is clear cell sarcoma. Most common pediatric renal mass is a Wilm's tumor. occurs after 2 month, claw sign with kidney
Gastric emptying study
99mTc sulfur colloid in a meal use anterior and posterior images to determine geometric mean of ROI (study uses the geometric mean), geometric mean accounts for better evaluation as it takes into account the anterior and posterior movement of food in the stomach. meal needs to be standardized 2-4 hrs length of imaging , >10% emptying at 60 mins, >35% at 90 mins, >40% at 120 mins, >90% by 4 hrs gastric hypermotility if <30% after 1 hr liquid has no lag phase and decreases in a monoexponential manner solids have a lag phase (5-20 mins) and decreases in a linear fashion after that. if pt has fasting glucose above 200mg/dl, reschedule avoid opiods, CCB, antacids, anticholinergic 48-72 hrs prior.
Dose pts outside nuclear medicine room
<0.002mrem(0.02mSeV/hr)
Incidental homogeneous adrenal nodule, next step?
<1 in 1000 likelihood of malignancy Patient should have biochemical testing instead
Carotid stenosis
<125 <50%, ICA/CCA <2.0 >125. 50-69%. ICA/CCA >2.0 >230 cm/s. >70%, ICA/CCA>4.0 most specific sign is peak systolic velocity.
colonic polyp size and cancer risk
<1cm <1% 1-2cm 10% >2 25%
Severe aortic stenosis
<1cm, gradient >40mmhg, >4m/s across valve.
To call a v/q scan low probability
<20%
external wipe test guideline
<2200 dpm/cm3
MQSA for radiation to single breast
<3mGy if using grid <1mGy if not using grid (mag view)
nuchal findings
<3mm at 9-12 weeks less than 6mm at second trimester in the unchallenged area
Oligohydramnios
<5 AFI Most common cause of oligohydramnios in third trimester is secondary to placental insufficiency during third trimester, leading to fetal growth restriction.
Cysts in postmenopausal women
<5cm in premenopausal women no need to follow up 5-7cm annual ultrasound >7cm MRI for both pre and post menopausal >1cm in post menopausal women 1 year follow up >7cm MRI
Milan criteria for liver transplant
<5cm single or up to 3 <3cm
nodules per fleischner
<6mm consider one year if high risk 6-8mm, 6-12 and 18-24 considered if low risk 6-8mm , 6-12 and 18-24 month mandatory follow up if high risk >8mm both low and high risk patients should consider CT at 3 months, PET/CT, and/or biopsy.
CTDIw
=2/3 CTDIp + 1/3CTDIc takes into account less radiation hitting the center of the patient
DEXA scores
>-1.0 normal -1.0 to -2.5 osteopenia <-2.5 osteoporosis
RV:LV ratio after PE to indicative right heart strain
>0.9
ABI
>1.4= noncompressible 1.1-1.4=borderline 0.91-1.1=normal 0.8-0.91=mild 0.5-0.80=moderate 0.31-0.50=moderate to severe <0.3= severe disease
stroke hemorrhagic transformation
>1/3 MCA territory, proximal MCA hit, more than 6 hrs without recanalization.
Right interlobular pulmonary artery
>15mm indicative of pulmonary arterial hypertension on the chest X-ray (this is the little finger pulmonary artery )
major spill criteria
>1millicurie I-131, >100millicurie Th and Tc, >10millicurie I-123, In-111, Ga-67.
Post transplant renal artery to external iliac ratio to suspect renal artery deformity
>2
splenic vein aneurysm
>2 or 2.5cm can intervene
When to treat splenic artery aneurysm
>2-2.5cm
Act
>200 is proper anticoagulation, normal is <150, for heparin you want 1.5-2.5 times above normal
how much glenoid is lost before surgery is considered post fracture?
>25% will create too much instability
Megacava
>28mm vena cava
NOF when they can cause pathological fracture
>3 cm, and comprising more than 50% weight bearing bone
size criteria to properly assess coronary stent patency
>3mm (86%), below 3mm (54%)
Hepatic adenoma size for increased bleeding and size for increased chance of malignant transformation
>4cm increased bleeding >5cm increased malignant transformation
Triangular cord sign
>4mm thickness of the anterior portal vein echogenic wall , in longitudinal axis, which is specific for biliary atresia.
Transmural enhancement
>50% involved
When should termination of early pregnancy be considered after fetal radiation exposure?
>50mGy, and between 2-15 weeks, not before or after .
Hemorrhagic cysts
>5cm should be followed by ultrasound in 6-12 weeks
endometrial thickness postmenopause
>5mm is worrisome, the greater the greater the chances of malignancy.
Maximum ovary size in a postmenopausal woman
>6cc
Large defect in v/q scan
>75% Moderate defect is 25-75% Small defect is <25% Triple match in upper/ mid lung is low, at base intm. Probability.
Sprengel's Deformity
A congenitally undescended scapula, may occur unilaterally or bilaterally, high riding scapula may indicate poorly developed or malformed scapula elevators. associated with klippel-fleil syndrome
Inversion recovery
A desired sequence can begin with a 180 degree pulse. This ____ ____ pulse can be used with either spin echo or gradient echo sequences. Then you calculate which tissue recovered to 90 degrees after this 180 Fat recovers faster than soft tissue which recovers faster than water (fat is T1 bright) STIR= you attenuate fat, use the principle that its inversion recovery is faster than that of water and grey matter. STIR is a fat suppression sequence. FLAIR= you attenuate water, so it'll take longer, since water has a long time to inverse compared to fat and grey matter. FLAIR is a fluid suppression sequence.
Billroth II procedure
A gastrojejunostomy, or surgical anastomosis, of the stomach and the jejunum. Increases risk of dumping syndrome, afferent loop syndrome Increases risk of gastric cancer in 20 yrs
A mode , B mode, M mode
A mode= send pulse, and wait for it to come back, time gives you distance. used in ophthalmology B mode=fan shaped pulse, can see multiple object, what we use M mode=similar to A mode only one straight pulse, but through the fetal heart, can tell distance changes with diastole and systole.
Window width
A narrow (decreased) window width increases contrast A wider (increased) window width decreases contrast The center point (or midpoint) of the level is going to determine the brightness. Window level (or center) = thing you change for brightness. Window width =thing you change for contrast Level up *higher pixel value*= for looking at dark stuff (lungs) Level down *lower pixel value*= for looking at bright stuff (bones) the window width determines the value of pixels in gray scale, anything passed the width will be white or black pixels.
Nail-patella syndrome
AD Iliac horns (osteochondromas), nail hypoplasia, patella hyperplasia, also elbows.
Lynch Syndrome (HNPCC)
AD non-polyposis syndrome with high risk of CRC Women should begin endometrial cancer screening 30-35 y/o
Charcot Marie Tooth
AD; common peroneal nerve palsy; inverted bottle appearance Nerve roots are big, onion bulb apeparance, compared to neurofibromas these dont enhance.
Primary sclerosing cholangitis vs aids cholangitis
AIDS has extrahepatic strictures >2cm, and papillary stenosis, usually no sacular deformity of the ducts PSC has extrahepatic strictures usually less than 5mm, sacular deformity (withered tree appearance) Both cause intra and extrahepatic stricturing
Holt Oram
ASD and upper extremity bone deformities including absence or hypoplasia of the thumb
atypical teratoma vs medulloblastoma
AT=has calcs, usually age 2 y/o Medulloblastoma= no calcs, usually 6 y/o
ATN vs rejection in post renal transplant
ATN will have normal perfusion, rejection doesn't. Both have decreased excretion on MAG3.
renal post transplant assessment
ATN, ischemic nephropathy or delayed graft function occur occur immediately after surgery and should recover during the first 2 weeks. acute rejection doesnt occur until after a few weeks and is most commmon in the first three months. renal artery stenosis will show occlusion in the inflow phase , renal vein thrombosis will show normal iliac artery inflow , but no uptake in the kidney. obstruction will show typical photopenia related to the dilated collecting system .
Susceptibility artifact in MRI
Ability of a substance to become magnetized by the external field, affects all pulse sequence, but most severe GRE (less than 90 degree pulses , more susceptible to susceptibility than spin echo sequences bc the 180 pulse in SE helps loose the T2 star effect. Making it better: Using SE and FSE instead of GRE Reduce magnetic field strength Fast/turbo spin echo-higher receiver bandwidth Thin slices (improves spatial resolution) Align longitudinal axis of metal with the axis of the magnetic field. decrease TE (less t2*artifact), or use fast spin echo (shorter TE as well) vs conventional spin echo(long TE). STIR Blooming worse at in phase (4.4 secs) than out of phase (2.2secs) bc T2 star increases with time.
Gallium 67 in the lung
Abnormal in the lungs after 24hrs. Usually due to infectious process, sarcoidosis, diffuse pneumonitis/pneumonia, exudative early post radiation pneumonitis, bleomycin.
When should grid be employed in IR based on patient thickenss
Above 10cm patient thickenss
bufford complex
Absence of the anterior superior labrum from the 1-3 oclock position You are going to see thickening of the middle glenohumeral ligament
Septooptic dysplasia
Absence of the corpus callosum, or septum pellucidum, associated hypoplastic optic nerve, hypothalamic/pituitary pathway defects. Main association is schizencephaly.
Adrenal gland washout
Absolute >60% : enhanced-delayed/ enhanced- noncontrast Relative >40%: enhanced-delayed/enhanced
Dose in radiology
Absorbed dose (gray)-energy absorbed -a physical quantity. X radiation weighting factor=. Equivalent dose (Sv) (biological effect-corrected for type of radiation, e vs alpha particles for example). Effective dose (Sv) is equivalent dose x tissue weighting factor. Biological effect on tissue type (if whole body then equal to equivalent dose). Takes into account organ sensibilities. fka[
Thymic cyst
Acquired after thoracotomy, chemotherapy, or HIV. T2 bright is going to seal the deal .
Swyer James syndrome
Acquired hypoplastic lung following severe obliterative bronchiolitis. Air trapping causes little change in lung size on expiration (different from congenital hypoplastic lung).
contraindications to thrombolysis
Active bleeding Intracranial neoplasmf AV malformation Suspected aortic dissection Ischemic stroke within 3 mo h/o intracranial hemorrhage closed-head or facial trauma within 3 months
acute obstruction in renal nuclear medicine
Acute obstruction will result in longer time to peak, longer excretion half life. ability to filter gets messed up before ability to secrete, so you want to use mAG3. if its not a physical obstruction, can check with diuretic, itll improve if its due to VCUG or previous obstruction.
Subacute thyroiditis
Acute, painful, post viral infection. Female after viral infection, you get hyperthrypoidism from spillling the hormone. Radiotracer uptake will decrease during teh acute phase.
Gamekeeper's thumb
Adductor aponeurosis impinges on the ulnar collateral ligament to reattach, leading to a Stenner lesion.
FNH vs Adenoma
Adenoma tend to have fat. Also Eovist will show 20 min retained contrast on the FNH, adenoma would be hypointense lesion
Lung scan
Administer the MAA with patient in supine position to reduce effects of gravities leading to more flow to the bases. Also if you're going to use tc99DTPA with T99 MAA, since they both are Tc, use less of the DTPA aerosol before the perfusion scan. You can get clots from drawing blood before injecting solution, it wont cause PE (insignificant).
Xenon vs technetium
Administer xenon first bc of its photopeak (81) vs Tc (140), so if you give technetium first it would degrade the xenon
Best agent to differentiate Alzheimer's from Lewy body dementia
Advanced Alzheimer's can hit frontal lobe real bad like lewy body, best test is F-18 Florbetapir (amyloid plaque assessment) , buil up around the cortex is indicative of Alzheimer's. Dementia with Lewy body will have an abnormal DatScan, while Alzheimer's will be normal also frontotemporal dementia DatScan will be normal.
placenta abruptio
After 20 weeks, see crescent hypoechoic tissue behind the placenta Maternal hypertension and cocaine abuse are risk factors
contraindications to breast radiation
After breast-conserving surgery, radiation therapy helps to control the microscopic disease, which has a comparable overall survival rate to mastectomy. Contraindications of whole breast irradiation include pregnancy, previous radiation, multicentric or diffuse disease, collagen vascular disease, and poor cosmetic outcome. Axillary lymphadenopathy is not a contraindication.
Retained products of conception
After d&c >5mm thickness in endometrium, Also after abortion.
Subclavian artery branches
After the first rib becomes the axillary artery After the teres major becomes the brachial artery
Crystal terminalis
Along the posterior right atria
Hip dysplasia
Alpha angle> 60 degree, seen on ultrasound Acetabular angle, its counterpart is measured on Plainfilm, should be less than 30 degrees.
Fast Spin Echo (FSE)
Also known as RARE or Turbo Spin Echo; A ___ ___ ___ sequence will produce multiple echos within a single repetition of the pulse sequence. For every TR, there's still only one RF pulse per TR. Multiple 180 degree excitations per TR.
Bilious vomiting 1 week to 3 months old
Always gets upper GI
FDG pet areas in brain pathology
Alzheimer's- temporoparietal, identical to Parkinson's, posterior cingulate gyros is first to go Multi infarct-multiple areas scattered Dementia with Lewy bodies-lateral occipital cortex, preservation of mid posterior cingulate gurus (cingulate island sign) Picks - for tall lobes Huntington's-caudate and putamen
Malignant calcifications in lung cancer
Amorphous (cloud like) calcs are more worrisome.
What location is ectopic pregnancy most common
Ampullary region of Fallopian tube
Automatic Exposure Control (AEC)
An electronic circuit within the x-ray machine that automatically terminates the exposure time when a predetermined quantity of x-rays has been detected. Increases/decreases exposure time , by changing mAs.
MAG3 captopril study
An increase or no change after captopril ingestion means that the RAS is not due to captopril. By giving captopril, MAG3 plasma clearance decreases in hypertensive patients with renal artery stenosis but increases in patients without renal artery stenosis
Coherent scattering
An interaction that occurs with low energy x-rays, typically below the diagnostic range. The incoming photon interacts with the atom, causing it to become excited. The x-ray does not lose energy but changes direction. The photon hits an electron that then leaves, with same wavelength and frequency as the incoming photon.
MIBG
Analog of noradrenaline (norepinephrine), can combine it with I-123 or I131, , I123 better images, I131 can be used for long term studies. Must block thyroid gland prior so no free iodine hits it. Normal MIBG distribution: liver, spleen, colon, salivary glands. Adrenals. NOT kidneys. MIBG superior to MDP bone scan for neuroblastoma bone mets. If you see skeleton on MIBG, the answer is diffuse mets. MIBG is superior to Pheo than In-111 Octeotride. Mets that interfere with MIBG, TCAs, calcium channel blockers, labetalol, reserpine, sympathomimetics.
Adrenal hemorrhage triad in kids
Anemia from hemorrhage, jaundice from breakdown of Hg in the liver, and an abdominal mass. Adrenal insufficiency is not a side effect, even if there is bilateral adrenal hemorrhage.
Causes of symmetric IUGR
Aneuploidy, congenital heart disease, intrauterine infection, TORCH
Indications for type 2 endoleak repaior
Aneurysm grows more than 5mm, first choice is endoleak embolization (not surgery or another graft)
before deploying stent for AAA
Aneurysmal free zone > 1cm Renal distance> 1.5cm less than 60 degree tortuosity aortic lumen (non-aneurysmal) up to 3.2cm.
Mandibular fracture with greatest risk of inferior alveolar nerve injury
Anglex fx, inferior alveolar nerve enters through second premolar region.
NRC regulations affecting the general public
Annual dose limit of 100mrem to public Not greater than 2mrem per hour-in unrestricted area Restricted area=any place that receives dose greater than 2mrem/hr Signs with slogans must be placed: Radiation area: any place could get 0.005rem (0.05mSv) in 1 hr at 30cm High radiation area: any place could get 0.1rem(1mSv) in 1 hr at 30cm Very high radiation area: any place out could get 500rads (1rad-1rem, 1 rad=0.01Gy) (5 gray) in 1 hr at 1 meter. total dose to general public from a licensed operation is 0.1rem or 1mSv per year. This doesn't include general background radiation or administered therapeutic doses, just radiation for being part of the public close to a radiation source I suppose. Occupational exposure dose limit Total body dose=5rem (50mSv) Dose to lens = 15rem (150mSv) Total equivalent organ dose per year: 50rem (500mSv) Total equivalent extremity dose per year: 50rem (500mSv) Total dose to embryo/fetus over entire 9 months: 0.5 rem (5mSv). If the fetus has already got 5mSv at the time fo declaration the NRC says you can get 0.5mSv more for the remainder of pregnancy.
Accuracy in dose calibrators measured how often
Annually
Haller cells
Anterior ethmoid cells that extend to the floor of the orbit.
Cecal bascule
Anterior folding and dilatation of the cecum without twisting, like a focal ileus, usually in the middle of the lower abdomen.
Approach to proximal tibial lesion
Anteromedial to avoid musculature, and popliteal areas.
Hydro/pyosalpinx
Antibiotics and drainge
TACE
Any enhancement post tx CT is residual disease. The oil used for TACE will be dense on precontrast images, the denser the better the outcome; post images will have dense site due to polivinyalcohol used.
when can you release pt home after I-131
Any of 3: dose 30-33mCi, not more less than 7mrem/hr at 1m exposed person to patient dose must not exceed 0.5rem(5mSv) per year.
SNR in MRI
Anything that increases your voxel size makes SNR better, the opposite of spatial resolution. Thicker slices - increased transmit RF pulse bandwidth - decreased slice selection gradient Larger FOV Smaller Matrix Stronger field , gets you more signal Increased number of excitations Increased receiver bandwidth will pick up more noise, narrow receiver bandwidth will pick up less noise! Smaller coil size Long TR,short TE (why proton density was made to have excellent signal to noise) Receiver bandwidth= thicker decreases SNR, but also decreases chemical shift and magnetic susceptibility artifacts.
Breast post radiation tx timeline
Anything worsening after 6 months is suspicious for recurrence (skin thickening, trabecular thickening, etc)
IR views for procedures
Aortic arch -LAO, Bascially LAO for everything except: 1. Brachiocephalic artery (right subclaviana nd internal carotid), 2. Mesenteric branches (celiac, sma, ima), and the iliac bifurcation (where you do the opposite, left iliac you do rao, right iliac you do Lao).
Motion artifact - Ghosting Appearance: Direction: Better: Worse: Comments:
Appearance: Duplicate copies, possibly many; May be shifted by 1/2 FOV; gross motion is seen as blurring Direction: Phase encoding Better:Saturation pulses, respiratory gating, faster sequences, eddy current correction, switch phase direction Worse: Sequences which place a high demand on gradient performance (EPI) Comments: Nyquist is when there are errors in gradient timing (EPI)
Chemical fat suppresion
Apply a presaturation pulse, an RF 90 degree at the fat resonant frequency, then wait for the fat signal to reach zero overtime, then you do another 90 degree pulse at other frequencies and then a 180 and you get the echo with signal not showing fat component. Types of fat suppression in MRI: STIR Dixon Chemical fat suppression (chemical presaturation pulse)
Fast spin echo
Apply multiple 180 degree pulses in between the 90 degree pulses, echo train length- number of echoes in the same TR, acquisition time is now 1/ETL Much shorte The multiple 180 degree create J couples, cause fat to lengthen on T2. With each progressive echo train the transverse signal gradually decreases, called T2 blurring.
What percentage of photons are scattered out of a patient in plain film radiography
Approximately 33%
Granulosa theca and sertoli tumors
Are sex cord tumors, not malignant germ cell tumors.
Aliasing artifact MRI
Area is undersmapled, occurs int he phase encoding direction Fix: Make FOV bigger, flip the PE/FE direction, surface coils, sat bands.
High riding coronary arteries
Arising >1cm above the sinotubular junction
Pancreas transplant
Arterial supply via SMA (inferior pancreaticuduodenal art.) and splenic artery. Venous supply via splenic vein and portal vein to the recipient SMV.
Phases of contrast in liver
Arterial=15-30secs Portal-70 secs Delayed-90 secs-5mins
Nuclear medicine crystals, detector efficiency and spatial resolution
As the crystal thickness increases there's more light scatter inside and less spatial resolution (more divergence), however the crystal that is thicker is more sensitive as high energy photons wont pass through it.
Origin of bronchus for the superior segment of the RLL occurs at the same level as?
As the origin of the RML bronchus
Pleural disease of the lung
Asbestos most common malignancy, pleural rind is a buzzword, extension to fissure is highly suggestive. Fibrous tumor of the pleura, not related to smoking, or asbestos exposure
Asbestos related pleural disease vs mesothelioma
Asbestos related disease does not involve the mediastinal pleura, mesothelioma does.
LUT(look up table)
Assigns contrast in digital receptors, its a histogram of known input intensities and corresponding grayscale. The primary factor influencing image contrast (in digital systems) is the LUT. The primary factors influencing image contrast (in film systems) is the kVP. KvP still influences digital receptors, but digital imaging receptors have a much wider dynamic range that can account for this.
Aortic caorctation
Assoc with bicuspid aortic valve, turner and noonan's syndrome, also cerebral aneurysms. Fixed by side to side anastomoses.
Pulmonary alveolar proteinosis
Assoc with nocardia, lymphoplaisa in kids <1, smoking, bronchoalveolar lavage is tx.
Von Hipple Lindau
Associated with CNS brain and optic hemangioblastoma, Endo lymphatic sac tumors, serous cystadenoma of pancreas and epididymal cystadenomas, pancreatic neuroendocrine tumors, RCC.
Middle aortic syndrome
Associated with Williams, agallile syndrome, or neurofibromatosis, narrowing of the infrarenal aorta.
H pylori and lymphoma
Associated with approx 85% causes of MALT lymphoma, usually cured after treatment of the bacteria.
Mitral annular calcifications
Associated with coronary artery disease , mild mitral valve regurgitation, and heart block, NOT associated with mitral valve stenosis .
Avian spur
Associated with impingement of the median nerve and the brachial artery Treatment is to release the ligament of Struthers.
Yolk sac tumor (endodermal sinus tumor)
Associated with increased Alpha-fetoprotein (AFP)
Sinus venous defect
Associated with partial anomalous pulmonary venous return
Sinus venosus ASD
Associated with partial anomalous pulmonary venous return, in which pulmonary veins enter right atrium, SVC or IVC. ASD near the vena cava. No tissue behind the defect on axial images, unlike primary or secundum which have septum in front and behind.
Dorsal pancreatic agenesis
Associated with polysplenia
Seminal vesicle cyst
Associated with renal agenesis, absence vas deferense, ADPKD (usually bilateral seminal vesicle cysts).
Left sided SVC and unroofed coronary sinus
Association, where there are fenestrations of the coronary sinus as it passes to the right atrium, leading to flow coming form the left atrium and into the left atrium. Creates a R->L and L->R shunt.
Astrocytomas vs ependymoma of the spinal cord
Astrocytomas tend to be long 5-7 segments, associated with cysts. Most common tumor in kids. Eccentric. Second most common in adults. Ependymoma tend to have hemorrhagic cap , superior and inferior peritumoral cysts. Concentric. Most common in adults. Hemangioblastoma tend to have a cyst and a nodule .
In spin echo sequencing when is the frequency encoded gradient applied
At TE.
Neonatal hydrocephalus
At birth , the size of the atria should be less than 1 cm.
Geometry in dose calibrators measured how often
At installation and when first placed
Amniotic cavity
At least 2cm on a vertical pocket Total, 5-20 cm is normal from 4 total biggest pockets, <5 oligo, >20 polyhydramnios , >8cm in a single pocket also polyhydramnios Oligo-not peeing enough Poly- gi issues, not drinking enough
Breast imaging facilities must keep records until how long, at least, unless requested by patient to be transferred elsewhere?
At least 5 yrs
Facial nerve enhancement
At the ganglion and the proximal tympanic (horizontal) segment its normal. Cistern->meatal->labyrinthe->ganglion->tympanic (horizontal)->mastoid->stylomastoid Ramsay-Hunt syndrome- herpes zoster oticus: enhancemtn of facial, vestibulocochlear nerves. Can see vesicles in external auditory canal.
Odontogenic keratogenic tumor (odontogenic keratocyst)
At the mandible ramus/body. True tumor, not cystic, usually not septated (unlike ameloblastomas/adamantimomas) , no significant cortical expansion reccurence up to 60%, need aggressive resection, curettage Associated with Gorlin syndrome (BCC of skin, cardiac and ovarian fibromas).
Ebstein's anomaly
Atrialization of the right ventricle. The right atria annulus is ok, but the leaflet migrates down, and makes the right ventricle smaller in capacity, this leads to enlarged heart mainly due to the right side. Box shaped cardiomegaly, paucity of pulmonary vessels.
Beam hardening = heel effect
Attenuation also occurs in the anode of the x-ray tube. Because the target is angled, there is a difference in the intensity of the beam exiting the target. The result is greater attenuation and beam hardening in the direction towards the anode, known as the heel effect. Compensation for the heel effect can be made by placing denser portions of the body on the cathode side and thinner portions of the body on the anode side of the tube, as is commonly done with upright chest x-ray imaging.
Holt-Oram Syndrome
Autosomal Dominant: Triphalangeal thumb, ASD, congenital heart disease.
Linear energy transfer
Average amount of energy deposited per unit path length of the incident radiation. Important for potential tissue and organ damage. Alpha particles have more LET.
Kaposi's sarcoma
Avid on thallium, like lymphoma Not avid on gallium 67- like pulmonary infections (PCP) or lymphoma
Reverse segund sign
Avulsion injury off the medial tibial rim, has high association with medial meniscus and PCL.
Arcuate sign
Avulsion of prox fibula, associated with PCL injury, also posterolateral corner instability cruciate ligament is corrected. It's horizontal in shape, following the contour of the fibulae head, unlike the segund (which tends to be vertical following side of the lateral tibia epiphysis).
Arcuate sign
Avulsion of prox fibula, associated with PCL injury, usually avulsion from biceps femoris or LcL with fibers affecting pcl.
Axial vs paraesophageal hernia
Axial the GE is above the diaphragm, paraesophageal the GE junction is below the diaphragm.
Bucky Factor formula
B = incident radiation on top of grid / transmitted image forming radiation; air kerma without grid/air kerma with grid
Tumors that are pet cold
BAC (ggg nodule per cold greater chance of cancer then pet cold) Carcinoid Rxcc HCC Anything mucinous Prostate
PET scintillators
BGO, original one. best absorption, but not best density so worse for resolution bc you need a thicker crystal which allows for more internal scatter. LSO- most dense crystal which allows for thinner crystals overall, better resolution. fastest decay time; to work again. the crystal thickness is what limits the spatial resolution .
high risk women
BRCA (plus untested first degree relative), hx of chest radiation, model showing >20% risk beginning age 25-30 or 10 years before age of first degree relative with breast cancer 8 yrs after radiation or above age 25, whichever comes later.
Toxo in kids
Basal ganglia calcifications Associated with hydrocephalus
Aortic stenosis criteria
Based on size >2cm -normal 1.5-2. Mild 1.0-1.5 Moderate <1.0 Severe <0.6 Critical
The transportation index
Based on the 1mm distance form package, how much radiation it emits, its essentially to assess transport based radiation.
Chemical shift artifact
Bc of difference in proton environment btw fat and water precession differences cause an artifact in the read out (frequency encoding direction). 2 subtypes: Type 1 - bright rim on one side and dark rim on the other. Chemical shift increases with field strength, decreases with increased gradient strength (increased spatial resolution, decreased SNR), and increased receiver bandwidth(decreased SNR). Type 2 - black line in all directions of the fat water interface, completely surround the structure On gradient echo sequences only, not on spin echo sequences. -fix by adjusting TE (longer TE), performing spin echo sequence (this only occurs in GRE, the spin echo equilibriums water and fat with the 180 pulse which makes everything in phase again) - type 1 occurs in both gradient and spin echo.
Sacroilitis in seronegative spondyloarthropathies
Begin at the iliac side (thinner of the two bones) inferior aspect (the synovial component , not the superior 2/3 of the SI joint which is fibrotic component)
Fetal Thyroid Gland
Begins to concentrate iodine at 10 weeks, before that receiving I-131 won't technically lead to cretinism.
Granulosa cell tumor
Benign and estrogenic, g for gal; in pedi it's usually premenopausal female
Hepatic adenoma
Benign fat containing lesions Can look just like HCC Regress with ocp stop >5cm remove, greater chance of bleeding
Ovarian fibroma
Benign lesions, like fibroids, t1/t2 dark, typically dont enhance Brenner's tumor- similar to a fibroma, usually older patients, 50-70 y.o.. 80% calcify.
follicular adenoma
Benign proliferation of follicles surrounded by a fibrous capsule (hypoechoic capsule)
Spatial resolution in ct
Besides normal X-ray: 1. Effective focal spot size 2. Motion 3. Detector There's: 4. Slice sensitivity profile (how much a detector picks up a point with minimal noise) 5. #projections , the more the more spatial resolution (hence why multidetector is better) 6. Pitch=spatial resolution decreases 7. Display field of view=pixels would be assigned to smaller area if you decrease display field of view, conversely if you have large field of view you have pixels covering larger amounts of space(more photons per pixel so greater noise). Large DFOV=smaller resolution.
Approach to biopsy proximal humeral lesions
Best is one that traverses the deltoid musculature anteriorly, just lateral to the delotpectoral interval. The deltoid is innervated from posterior to anterior, therefore biopsies and surgeries are performed via anterior approach.
SEGA vs subependymal nodule in TS
Best way to differentiate is size, bc both can enhance.
Dose for sarcoma induction with radiation
Between 5000-6000 cGy
Zenckers diverticulum (False diverticulum at pharyngoesophageal junctions)
Between the cricopharyngeous and the thyroparyngheous fibers of the inferior contrictor.
ADEM
Big irregular high t2 signal lesions, tend not to be periventriculor or callosal like MS. Will be monophasic. Can show variable restriction.
Amyloid arthropathy
Bilateral, no loss of joint space narrowing, 80% get it after ten yrs of dialysis, bilateral involvement of shoulders, hips, knees, hands, can be very destructive (look like neuropathic arthropathy)
Absent gallbladder
Biliary atresia Biliary atresia is associated with polysplenia
Tc99 MDP
Binds to calcium hydroxyapatite off bone.the mineralized portion of bone
Binning in FPD systems
Binning: takes several detector elements (DELs) to make a large DEL (only with FPD, not II) Concept: ↓ the amount of data → ↓ variation in x-ray photons from pixel to pixel and ↓ quantum mottle With ↓ mottle, you can ↓ radiation and keep the same noise Larger DEL does ↓ spatial resolution Binning is especially useful with large FOV (where there are too many pixels in the image) Binning and spatial resolution: -Binning: large FOV will have lower spatial resolution (but can use less radiation to maintain the noise level) -No binning: spatial resolution doesn't change with different fields of view. Small FOV: dose is increased to reduce quantum mottle -Binning improves SNR and decreases dose needed, but also decreases spatial resolution.
Fetal profile
Biparietal circumference =from outside skull to the inner table (can be affected by brachiocephalic, early closure of lambdoid or coronal sutures, so it grows via sagittal and hence becomes a wide head circumference ), measured at thalamic level. Head circumference= uses only bone, also at thalamic level Abdominal circumference = at the umbilical vein left portal vein level Fetal length= longest part of shaft, doesn't use the epiphysis.
More accurate measurement of fetus during second trimester
Biparietal diameter. Moreso than abdominal circumference of femur length.
Fettal biometry profile
Biparietal diamter recorded at level of thalamus, from outer edge of skin to inner table, affected by shape of skull Head circumference , at thalmus, does not include skin Abdominal circumference at level of junction of umbilical vein and left portal vein. Femur length, does not include the epiphysis.
False negative in mammography
Birads 1,2, or 3 that resulted in cancer in 1 year.
PET QA
Blank scan- use a positron source Ge68 or Cs137 by itself, or a uniform source cylinder with that inside, done daily. This uniform test is done daily. Also use an analog of daily flood, don't want to see any crazy lines. Normalization scan- similar to blank scan, either by taking a point source(usually Ge68) and rotating it around the periphery of the FOV, or using a cylindrical source. Idea is to expose the detectors to a uniform flux of positrons.
Neonatal hypoglycemia
Blood glucose of 40 or less or in a preterm newborn 25 or less Restricted diffusion in cortical parietooccipital regions, with general sparing of the brainstem, thalami and other areas, only really seen like this in neonates (also infants of diabetic mothers, for unknown reasons).
Doses for specific organs
Bone marrow >2Gy GI >8Gy CNS >20-50 Gy 50/30 rule, 50% dead by 30 days, 3-4Gy of exposure. acute radiation syndrome=clinical response to large amount of radiation, dependent on organ system with doses as above. CT Abd/Pelvis is 30mGy for example, these doses above are in Gy.
Gallium-67 scan
Bones, light spleen, has uptake in lacrimal and salivary glands Half life 78 hrs Dose 4-5mCi Used for lymphoma and sarcoidosis (hot nose panda sign)
PVSN vs amyloid arthropathy 2/2 renal failure
Both T1/T2 low, but PVNS will show susceptibility on gradient echo from the hemosiderin.
HMPAO AND ECD
Both are lipophlic with high extraction capacity, sampled at 30-60mins to increase target to background ratio
Ovarian mucinous cystadenoma vs ovarian serous cyastadenoma
Both benign lesions Mucinous tends to be multilocular, serous tends to be unilocular.
AML vs renal cell
Both can be hyperechogenic, but AML usually presents with posterior acoustic shadow, which renal cell doesn't. Renal cell also has calcification, which aml won't on test.
Enchondroma vs chondrosarcoma
Both can present with chondroid matrix, endosteal scalloping, and pathological fractures. Cortical destruction and soft tissue mass are features of chrondrosarcoma. Lesions pain and increased uptake on bone scan (greater than anterior iliac Creasy) are also highly suspicious for chondrosarcoma.
Geometric magnification
Both geometric and electronic magnification increase dose, but electronic to a lesser extent , SID/SOD is geometric magnification, geometric uses smaller focal spot, better spatial resolution, more radiation, more blur at the peripheral aspects of the receptor.
Relapsing polychondritis vs tpo
Both have anterioateral tracheobronchial wall thickening , both have calcs. Tpo calcs are submucosal extending to the mucosa. Relapsing polychondritis calcs are diffuse. Relapsing polychondritis also involves the nose, ears, skin, tpo is limited just to tracheobronchial tree.
Rebound thymus vs lymphoma
Both hot on PET, lymphomas tends to be hotter Thymic rebound should drop out on in-out of phase imaging (has fat in it), lymphopma wont.
Patients over 30 with breast lump
Both mammogram and ultrasound
Tc 99 HMPAO and Tc 99 ECD
Both used for brain death studies , both lipophilic, can cross BBB. Tc DTPA is not lipophilic, but all three can be used for brain death scans.
Thymoma vs thymic hyperplasia
Both will be T2 bright Thymic hyperplasia will demonstrate loss of signal on in and out of phase imaging, thymoma won't.
How to tell Pagets from malignant transformation on MRI
Both will show high T2 signal , and avid enhancement T1= Pagets will have new yellow marrow conversion specks which will be bright, malignant transformation will not. Malignant transformation is also cold on nuclear medicine scan. T1 scan in general is best to assess for bone marrow involvement of lesions.
In-111 WBC and Tech sulfur colloid combined study
Both will show physiologic uptake, In-111 should supersede Tech to see an infected joint. You used combo bc sometimes In-111 will have physiologic uptake in the joint. By doing combo, this physiologic uptake is corrected as it will be present on both studies and will therefore be subtracted out.
When is superior sulcus tumor nonresectable
Brachial plexus is hit (anything above T1) More than 50% of vertebral body size Diaphragmatic issues (infers c3-c5 is hit)
anterior chorodial artery
Branch off the ICA terminus, right above the posterior communicating artery . Feeds the posterior limb of the internal capsule, choroid plexus of lateral and third ventricle, optic chiasm, hippocampus, and amygdala.
Organ radiation sensitivity
Breast>gonads>thyroid>skin
Brightness gain in II
Brightness gain- minification gain x flux gain Less minification (smaller FOV= magnified= less brightness More minification (larger FOV= less mag= more brightness
Paraovarian cyst
Broad ligament cyst, from the wolfian ducts. Adjacent to the ovary, will push on it but not distort the ovary
Bucky factor
Bucky factor = dose with grid/dose without grid. Typical factors are 2-3 which means the entrance skin dose is typically 2-3x greater when using a grid.
Corpus luteal cyst resolves at what time in pregnancy
By 16 weeks
Talocalcaneal coalition
C sign, best seen on the lateral view, usually the Talar dome and the sustentaculum tali (middle calcaneal facet) Talar beak sign also associated with talocalcaneal coalition, also best seen on the lateral view, due to impaired subtalar motion
What are the four RNC measures of dose calibrators
C-LAG Constancy-daily-should be within 5% daily. Linearity-quarterly Accuracy-yearly Geometry-when installation Dairy Queen Always Open- daily, quarterly, annually, on repair.
Mickey mouse sign
CBD is the right ear, hepatic artery is the left ear On sagittal the CBD is anterio then the hepatic artery and posterio is the portal vien.
how is a normal stereotactic performed
CC view with +15 and -15 degrees to localize the lesion
AIDS related pulmonary lymphoma (ARL)
CD4<100. Lung nodules, pleural effusion and lymphadenopathy ((pcp doesnt give lymphadenopathy, and usually also has cysts).
Hyaline chondrocalcinosis associations
CPPD, hyperparathyroidism, and hemochromatosis, NOT rheumatoid arthritis
Detectors in mammography
CR (psp) Direct flat panel (selenium, like in Hologic)
Pregnancy failure guidelines
CRL>7mm Gestational sac >25mm and no fetus No cardiac activity after gestational sac but no yolk sac seen >2weeks No cardiac activity after gestational sac and yolk sac seen >11 days
Acr criteria for adult suspected of Crohn's
CT enterography, followed by MRI enterography, and small bowel follow through. For kids, CT enterography or MRI enterography For perianal fistula or perinatal disease MRI is first choice
CTDIvol
CTDIw/pitch
Jumpers knee
Calcification on plainfilm below the proximal patellar tendon. On MRI will see high signal about the proximal patellar tendon, usually seen in bball.
Peyrione's disease
Calcification, usually linearly distributed along the tunica albugenia (which surrounds the corpora cavernosa and spongiosum)
Phase contrast imaging in mri
Calculates blood velocity info (speed and direction) using a phase encoding gradient along the long axis of the vessel. Slices are typically oriented to cut through the short axis of the vessel. To a void aliasing in phase contrast imaging,set the velocity encoding parapets (Venc) slightly larger than the maximum velocity.
Echo planar imaging
Can be done with spin (90 then 180 RF) or gradient (90 and then bunch gradients). Fastest MRI acquisition. One RF pulse is used to acquire data for an image (aka single shot) Works by turning the phase and freq encoding gradients on and off very rapidly. Causing rapid filling of the k space. Most vulnerable to magnetic susceptibility, better tissue contrast, and is faster, compared to GRE. This is what's used for Diffusion Weighted imaging. utilizes strong bipolar gradients to assess moving vs nonmoving objects (intravoxel for echo planar (dwi) and for phase contrast study).
Posterior ankle impingement syndrome
Can be due to os trigonum, Haglund's deformity (elevation posterior process of calcaenous ), hits the posterior Talofibular ligament , commonly seen 2/2 plantarflexion most common in ballet dancers.
Stable pt w/ splenic pseudoaneuryms
Can embolization proximal splenic artery distal to the first branch (dorsal pancreatic) or distal splenic artery, the proximal approach will create collateral s so there wont be splenic infarct, and the distal approach is subselective.
seminoma
Can have elevated hcg and ldh, but not alpha feta protein mediastinal seminoma tx=> chemo and radiation alone. surgerys reserved for residual lesions after chemo and radiation.
Anomalous origins of the left coronary artery
Can have interarterial path or interseptal which is less severe (the left main courses below the pulmonary valve through the ventricular septum.
Thymoma
Can range from thymoma to thymic carcinoma, if you see calcifications its usually worse prognosis.
Ammonia
Can result in multifocal areas of cortical restricted diffusion , the ammonia gets converted to glutamime which absorbs fluid, hence edema, usually due to alcoholics with acute decompensation, shunts, or GI bleed .
Sign of constrictive pericarditis
Cardiac septal bounce during diastole
Juvenile arthritis
Carpal bones are jacked up in comparison to MCP and phalanges; early ankylosing(joint space narrowing) klippel fleil vs juvenile arthritis of the spine-klippel has shortened AP dimension of vertebral bodies, both can have vertebral body fusions.
S distortion
Caused by electromagnetic interference -it is caused by magnets -if you remove the magnet then you will remove the distortion, instead of straight rectangular lines you get wavy lines. -only seen in II
ARPKD (Autosomal Recessive Polycystic Kidney Disease)
Caused by mutations in PKHD1, large kidneys, multicystic (but cysts are so small the kidney is echogenic), associ with hepatic fibrosis, including Caroli's , BUT NO INCREASED RISK OF BERRY ANEURYSMS). The lighter the ARPKD the worse the liver fibrosis.
Proper location for portacath tip
Cavoatrial junction, 2 vertebral bodies below the carina fluoroscopically
Cck, morphine, cimetidine, and phenobartbital
Cck= causes contraction of gallbladder, used to assess chronic cholecystitis , <30% is diagnostic. Morphine= is given after 1 hr of lack of visualization of into the bowel, used to enhance exam study. stimulate sphincter of oddi, used to assess for chronic choleccystitis, ef<30% is chronic cholecystitis Cimetidine= used to decrease gastric mucosa release of pertechnetate from mucin producing cells of teh ectopic gastric mucosa, for meckel's scan Phenobarbital= given 3-5 days prior to prime the hepatic enzymes to take the hida, 5mg/kg
Congenital rubella in msk
Celery stalk—> longitudinal aligned linear bands of sclerosis. Seen first weeks of life, syphilis presents 6-8 weeks of life. Syphilis- wimberger sign—> destruction of the medial portion of the proximal metaphysis of the tibia.
Cells radiosensitivity
Cell damage is directly proportional to degree of reproductive ness, and inversely proportional to degree of differentiation.
Budd chiari or anything that causes nutmeg liver
Central arterial enhancement, peripheral minimal; portal- central washout, peripheral enhancement.
Central Neurocytoma vs subependymoma
Central neurocytoma avidly enhances, attaches to the septum pellucidum, younger patients 30-40s y/o. Both are T2 bright though, and may contain cysts.
Fibrolamellar cancer
Central scar, not T2 bright or enhancing (unlike FNH) Can calcify (unlike hcc which is rare) Afp not elevated Gallium avid (FNH is sulfur colloid avid)
Cephalohematoma vs subgaleal hematoma
Cephalohematoma respect sutures, subgaleal does not and can spread throughout causing hypovolemia.
Automatic brightness control
Changes the kVP, filter and pulse width(exposure time).
Increased renal activity on tech-MDP bone scan
Chemotherapy is quite common, iron overload makes bone agents go to kidneys, sickle cells, ATN, also can result in this; high grade obstruction will show no tracer in bladder and accumulation of tracer in soft tissues from bakcflow. Hypercalcemia will also lead to increased renal uptake. seen by the kidneys having more uptake than the vertebral bodies on posterior porjection.
Gallbladder adenomyomatosis
Cholesterol deposits in the rockitasnky Ashcroft sinuses that result from hyperplasia of the mucosa and muscularis propia.
Cholesterol granuloma vs cholesteatoma
Cholesterol granuloma is T1 AND T2 bright. Cholesteatoma is T1 dark and restricts. both allow for smooth scalloping of the temporal bone. Cholesterol granuloma tends to be in petrous apex, or middle ear, acquired cholesteatoma invovles the scutum (epitympanic region), while congenital cholesteatomas tend to be medial to the ossicles (with ossicle erosions as well).
Lesions in the posterior half of the lateral ventricles
Choroid plexus carcinoma (<5 yo, ugly lesions), choroid plexus papilloma (stalk and vascular), xanthogranulomas (can restrict , <1cm), meningioma (usually females 30-60 yo) SEGAs are in the anterior half of the lateral ventricles, at the level of the foramen of Monroe.
Choroid plexus neoplasm
Choroid plexus papilloma, choroid plexus carcinoma can all seed, and can all cause hydrocephalus from either too much CSF, or proteinaceous blocking of CSF from mass effect.
Hepatopulmonary syndrome
Cirrhotic, with prominent vessels at lung bases, whichshunts blood there. Can see with Tc-99MAA scan showing R->L shunting. Have to show you a cirrhotic liver.
Corona mortis
Classically described as connection between the obturator artery and external iliac artery. The vessel actually arises from the inferior epigastric artery (off the external iliac) to the internal iliac (going lateral to anteromedial). Vessel shown coursing over the superior pubic rim Can be injured in pelvic trauma or surgery.
Myocarditis on cardiac MRI
Classically nonvascular distribution subepicardial enhancement, also can be muscular enhancement Classically early enhancement is also seen (due to inflammation) Worse prognosis is biventricular dyskinesia/akinesia.
Sulfur colloid scan
Classically to differentiate FNH from hepatoma (positive on FNH) Cavernous hemangioma cold, hot on RBC scan HCC cold, hot on gallium Abscess cold, hot on gallium Focal fat cold, hot on Xenon. Diffuse pulmonary activity, may be seen from excess aluminum in the colloid. CHF can cause renal uptake of sulfur colloid. Also renal transplant can show up on sulfur colloid if there's suspicious of rejection.
Clean procedure, clean-contaminated, contaminated, and dirty procedures
Clean-gi, GI, and respiratory tract is not involved Clean-contaminated-involvements go gi/gu tracts without inflammation, like percutanoeous gastrostomy Contaminated-neprhostomy tube placement Dirty-inflammation with pus, abscess- anastomoses breakdown drainage
Coat's disease
Coat's disease: caused by retinal telangiectasias → can lead to retinal detachment Young boys, typically unilateral Not calcified Smaller size eye , retinoblastoma has calc and normal size eye
Findings associated with developmental hip dysplasia
Coax magna (big femoral head and wide femoral neck), results in femoral shortening. Acetabulum is retroverted in 37% of cases. 20% bilateral, so image other hip.
Ways to reduce scatter
Collimator-reduces the area of the beam Compress the part- reduces thickness Lower kVp- reduces Compton scatter, trade off is increased dose(skin*) Grid/air gap
Sulfur colloid and WBC imaging
Combined tc-sulfur colloid and wbc study is positive for infection if there's activity on the wbc image, without activity in the Tc sulfur colloid scan. Now you can have false neg with no activity on wbc scan in spine, so you need to use Galium for the spine (gallium more specific), see decreased activity on tc sulfur colloid with high gallium, its infection. Prosthetic evaluation: diffuse surrounding hot uptake can be infection , loosening is more focal at the stem and lesse trochanter. Tc99HMPAO WBC: Tc99 HMPA WBC can be used in kids (Tc has shorter half life ) and better at seeing smaller parts compared to In-WBC.cannot use Tc all time bc its uptakes in bowel and GI system. Indium-WBC critical organ is the spleen. Critical organ is the first organ to be subject to radiation passed the allotted limit.
Ductal carcinoma in situ subtypes
Comedo, solid, micropapillary, papillary and cribiform.
dose length product (DLP)
Commonly reported dose descriptor on CT scanners. Calculated by multiplying the CTDIvol b the length of he scan(cm), DLP=CTDIvol x scan length. CTDIvol= CTDIweight/pitch
GRE
Compared to traditional spin echo, has bipolar read out gradient (frequency-encoding gradient) to create and echo (as opposed to a 180 degree refocusing RF pulse), smaller flip angles (<90 degrees and often < 30 degrees), and greater T2* effects, and residual transverse magnetization. This occurs if the transverse magnetization vector is not allowed to fully relax btw each excitation. Residual transverse magnetization can contribute to the MR signal and alter tissue contrast. To prevent use RF coiling and spoiler gradients (I.e. spoiled gradient echo). Spoiling destroys residual transverse magnetization, permitting even faster acquisition times of T1 weighted images.
Technetium 99 DTPA aerosol
Compared to xenon , it has two limitations, sensitive to air turbulent flow (so like a tracheal mass can lead to focal uptake in the trachea due to altered flow dynamics leading to clumping in the major airways) and it does not demonstrate areas of air trapping Positive is that its technetium, perfect for gamma camera, and remains for a while, so can do multiple images with dose. Biological half life is about 80 minutes, but it significantly decreases in smokers due to changes in vasculature in smokers. its excreted through the bloodstream via kidneys, in smokers it cant be absorbed as well.
Testicular Torsion Etiology
Complete coverage of the testis by the tunica vaginalis, normally it shouldn't surround the entire testicle. While intravaginal torsion is more common overall, extravaginal torsion is more common in newborns assoc with undescended testes. Tc-pertechnetate can be used to assess for torsion.
RECIST 1.1 response
Complete response -resolution of all target lesions, <10mm short axis Partial response- >30% decrease in sum of diameters compared to baseline sum of diameters Progressive disease- >20% increase in sum of diameters compared to smallest sum of diameters ever measured on the current study proctologist's and absolute increase in the sum of diameters >5mm. New lesion also comprises progressive disease. Stable disease- does not qualify for complete response Lesions greater than 15mm in short axis qualify as target lesions in RECIST 1.1 , these can be followed and measured reliably overtime. Lesions within solid organs must be greater than 10mm in long axis to be considered "target" lesions. This diff is bc lymph nodes are normal structures , while lesions within organs aren't. Each pt can be assigned a maximum of 5 total target lesions to sum it all up in RECIST.
Boorhave's
Complete tear of the lower esophagus wall, gastric contents spill into the thorax, usually associated with a left sided pleural effusion. Rarely presents with hematemesis as blood just spills out of the esophageal wall.
Triple phase bone scan
Complex regional phase—> shows increased uptake even larger on delayed phase than prior 2 phases Osteomyelitis —> triple phase positive but tends to be very focal
Compton and Photoelectric effect based on energy
Compton 1/E PE 1/E^3 So, PE drops more than Compton in higher energies, however both drop nonetheless, why higher kEV photons can penetrate more tissue, less interaction.
Types of ionizing radiation
Compton scatter, PE effect, and Raleigh scatter (coherent scatter) are ways photons interact with matter. Breumstraugh is when electrons interact with the anode target.
Medullary sponge kidney
Congenital , asymmetric, cystic dilatation of teh collecting tubules of the kidneys, associated with Ehler-Danlos, and Carolis.
Mounier-Kuhn Syndrome
Congenital abnormality of the trachea and main bronchi\ Characterized by cystic dilatation of the tracheobronchial tree, which then collapse on exhalation. Pathologic findings Atrophy or absence of elastic fibers and thinning of muscle of the trachea and central bronchi Rapid change to normal caliber at the 4th-5th order of bronchi More common in males (95%), particularly african 20s to 30s Autosomal recessive Predisposed to Pulmonary fibrosis Emphysema Bronchiectasis Chronic pulmonary suppuration Clinical findings Recurrent pneumonia Dyspnea Cough Hoarseness Production of copious amounts of purulent sputum consistent with bronchiectasis Imaging Findings Tracheobronchomegaly (see below) Tracheal size increases with Valsalva and narrows with Muller maneuver Saclike outpouchings between tracheal cartilages Pulmonary fibrosis Bulla Bronchiectasis Associated with Ehlers-Danlos syndrome
Kippel-Feil Syndrome
Congenital fusion of any 2 of the 7 cervical vertebrae. also associated with sprengel deformity, where the scapula is high riding due to lack of caudal migration (most common shoulder abnormality, aka duancel)
Congenital vs traumatic radial head
Congenital radial head presents with overgrown and dysplastic congenital dislocation .
Dentigerous cyst
Congenital, cyst from the crown of the tooth, keeps the tooth from erupting, congenital
Transformers in xrays
Contain two wires, the more turns within the secondary coil, the greater the voltage in the secondary coil.
CNR
Contrast /noise Contrast is proportional to #photons in a voxel, so contrast also increases, ; noise is proportional to square root of photons, so overall both increase but contrast more, so CNR increased. CNR is also proportional to 1/Pitch
Collimators in nuclear medicine
Converging collimators increase image, diverging decrease focal spot of image, parallel do neither. Pinhole collimators magnify small object. Increase the size of the pinhole (same general principle as other collimators= sensitivity increases but resolution decreases).
Pa gets disease of bone
Conversion to osteosarcoma would result in photopenic areas on bone scan from the developed osteosarcoma
X ray generators
Convert ac to direct current Increase voltage across an X-ray tube Can control current within x ray tube Controls duration of time of current within an x ray tube
Ovarian dermoid tumor transformation
Convert to cancer in 1-2 % of cases,to squamous cell carcinoma.
PMT (photomultiplier tube)
Converts the light energy to electrical energy, which turns into x and y plane. The z axis is determined by pulse height analyzer which determines the strength of the signal and can discard background from emitted signal that we want.
Direct digital detector
Converts x ray directly into digital signal without intermediate photodiode to thin film transitors or ccd camera, its what's used in hologic in mammo, still sends it through a thin film transitor also. Uses amorphous selenium.
Not hot on bone scan
Cortical Desmond (tug lesion of medial distal femoral diaphysis); hemangioma and bone island.
If you see increased uptakes in liver, spleen and bone marrow in Tc99-DMP (bone scan study)
Could be from excessive ion breakthrough in the elluate, forming the Sulfur colloid which attaches to the liver, spleen and bone marrow.
Types of male cysts
Cowper- below the prostate, at the level of the penis, come off Cowper glands which feed into theurethra, they are lateral Seminal vehicle- lateral cysts, assoc with renal agenesis, vas deference exculpatory duct agenesis Ejaculatory duct cyst-lateral cyst Bph cyst- associated with bph, cysts are inside the big prostate. Mullerian remnant cyst- midline cysts, these tend to project above the apex of the bladder
Prune Belly syndrome
Crappy abdominal wall musculature, hydroureteronephrosis, and cryptoorchidism (big bladder does not let the descend of the testes).
Roux-en-Y
Create a small gastric pouch Excluded stomach attaches to the duodenum The jejunum is attached to the other jejunum to form the bottom of the Y. Increased risk of gallstones and internal hearnias.
Gallium 67
Critical organ is the colon, half life of 3 days, peak energies, 100. 200. 300. 400. Images are read after 24 hours. PCP is positive in gallium 67, kaposis is negative Bacterial pneumonia wil pick up gallium without parotid or nodal uptake, normal to have some gallium uptake in lungs and kidneys until 24 hrs, after Ga67 uptake passed 24 hrs is indicative of pneumonia or renal issues .
Intersection syndrome
Cross over of the first and second dorsal carpal row , usually seen in rowers.
RF related artifacts
Cross talk- excitation of neighboring sections more than once in a single repetition. Lead to partial saturation and lower signal. Increase the gap in the sections, use a steeper gradient. Doesn't happen in 3D bc you sample entire volume with excitations. Zipper artifact- random RF signals, close the door, eliminate all electronic devices, tends to occur in the phase encoding direction.
Intersection syndrome
Crossing over of the first and second extensor tendons of the wrist Results in injury to the 2nd extensor row (extensor carpi radialis longus and brevis ) 2nd extensor row is lateral to listler's tubercle
Croup vs subglottic hemangioma
Croup will show steeple and sick kid Subglottic hemangioma will show a unilateral subglottic fullness Exudative trachitis (filling defects in airway , 6-10 yo, staph) Epiglottitis will show thumb sign Retropharyngeal abscess, >6mm at c2, more than 22mm at c6.
Pregnancy failure
Crown rumps length >7mm and no heart beat Gestational sac >25mm and no fetal pole Gestational sac , no yolk sac, and no fetal pole after 2 weeks Gestational sac and yolk sac but no fetal pole after 11 days.
Stages of bladder cancer
Ct and MRI are not that good, usually do new via cystoscopy with muscle wall biopsy. Stage II=muscle invasion Stage III=passed bladder wall Stage IV=hitting abdominal wall or other organs
Earliest parenchyma change in asbestosis
Curvilinear noncalcified densities, why its important to obtain prone images early on.
Cyanide, carbon monoxide and methanol
Cyanide and carbon monoxide like the globus pallidi Methanol likes the putamen and white matter, optic nerve (moonshine makes you blind)
Thymoma
Cystic mass with mural nodularity, usually someone > 50. Teratoma and germinoma occur in younger (<40 yo , typically)
PXA vs desmoplastic infantile ganglioglioma (DIG)
DIG is in a kid less than one, big cystic lesion with hydrocephalus, PXA is older kid (with a cyst and a nodule, usually upper lobe)
DIP vs RB-ILD
DIP is ggg in the lower lobes, RB-ILD is GGG nodules in the upper lobes .
Technetium 99 DTPA vs Technetium 99 MAG3
DTPA has a lower target to background ratio bc a lot less of it (only 10%) is bound to protein, so a lot of it dissipates extravascularly. MAG3 , 90% of it is bound to protein.
Darkroom cleanliness quality control is performed how often for mammo?
Daily
MQSA mobile unit quality control testing
Daily
Processor quality control for mammography should be performed how often
Daily
Constancy in dose calibrators measured how often
Daily, using a long lived source like Cs-167
Subcoracoid external impingement
Damages the subscapularis (coracoid and subscapularis tendon are anterior)
Subacromial external impingement
Damages the supraspinatus and infraspinatus, usually the result of the overhead throw or swimmers. most commonly it hits the supraspinatus, like from hooked shaped acromion, osteophytes. subcoracoid will hit the subscapularis, both are anterior structures.
Solid pseudopapillary tumor of the pancreas
Daughter lesions No calc Capsule Bleeds Asian girls, in their 30s
How to decrease reverberation artifact
Decrease gain or power, or change angle of the probe
Smaller focal spot, what must you do to KVP
Decrease it , not to burn the anode. Smaller focal spot leads to decreased power Sharper resolution But more noise, bc decreased KVP
Iterative reconstruction algorithm
Decrease quantum noise and allow for lower dose CT scans. Analytic reconstruction algorithms use filter back projection which is faster but result in more noise and streak artifact.
Biphosphonate fractures
Decrease risk of hip fractures, but increase the risk of subtrochanteric and diaphyseal femoral fractures
decrease dose in CT based on kvP
Decreased kVp , unlike in mammo theres no phototimer in CT, so you get less kVP you lower radiation (also get better contrast with less kvp), and you get less mA (15% rule, drop of 15%kvp decreases mA by 50%). In real life cases you want to decrease the kVP and increase the mAs slightly to compensate for the drop in kvp (which also decreases mAs) unlike other xray modalities, you mess with the kvp to decrease dose in CT (bc theres no phototimer)
Hepatic hemangioma
Decreased uptake on tc 99 sulfur colloid, increased uptakes on Tc99 RBC scan Only liver lesion that takes Tc99 sulfur colloid is the FNH.
Higher receiver bandwidth
Decreases SNR but improves image time and diminished chemical shift artifact, also diminished metal artifact.
Quantum mottle
Decreases by the square root of the change of the number of electrons (mA)
Increasing the receiver bandwidth
Decreases signal to noise ratio(more noise enters with wider capability to pick up signal), less TE (more amplitude of signal read out gradient, so less time to get to the echo and faster sampling), less mis-mapping artifact (less chemical shift artifact).
Increase receiver bandwidth
Decreases signal-to-noise ratio (more signal), decreases the time in TE, lowers TE (able to get more signal per phase). Less susceptibility (less T2* which happens with longer TEs), and chemical shift artifact also. TE is time from RF pulse to the echo (long TE gives you T2, but more susceptible to t2*).
If you increase optical aperture on the II what happens to air kerma
Decreases, bc the automatic control will sense more light and decrease the number of photons needed.
PRF
Decreasing PRF= increased aliasing, increased sensitivity to slow flow, and increased depth.
Osteopetrosis
Defect in osteoclasts activity , the bone cant resolve, so you have normal osteoblasts actings, and so you don't really form a corticomedullary differentiation.
Cholangiocarcinoma
Delayed enhancement , bc it forms fibrosis, scarring Encases the portal vein (HCC invade the portal vein) Focal biliary dilatation Hepatic capsule retraction, the lesion doesn't have a capsule
Dentigerous cyst vs odontogenic kertogenic cyst
Dentigerous cyst is a congenital variant that arise from the unerupted crown of a tooth, unicystic. The odontogenic keratgenic cyst completely surround the tooth, giving it a floating appearance. The periapical cyst occurs from the root of the tooth, usually abscess then.
GRE (gradient recall echo)
Depends on flip angle and TE, increasing the flip angle leads to increase T1 signal. Usually the flip angle in GRE compared to spin echo is smaller than 90 degrees.
Focal spot blur
Depends on geometric structure. Directly proportional to the object to detector distance and inversely proportional to the x ray source to object distance.
Lateral resolution in ultrasound
Depth dependent , notion of focal zone (where you have the best lateral resolution), area closer to focal zone is called near field and far field is far. Lateral resolution is also dependent on density of scan line. Density of scan lines increase lateral resolution, more scan lines better lateral resolution. Density of scan lines is closer to the probe before they diverge, so lateral resolution is worse distally, so something far be sure to adjust focal zone position. Increased TF increases axial and lateral resolution. 1. Beam width 2. TF . Higher TF (lower wavelength)-narrower beam width in far field. The TF is also tied to SPL. 3. Density of scan lines near field= (element size)^2/wavelength; increase in element size will increase the near field by a square of the increase. 5 elements in an array are often pulsed simultaneously , effectively creating an element thats 5 times wider. This lengthens the near zone by a factor of 25. higher frequency probes have increased near zones (since the near field= element size/wavelength then the lower the wavelength the greater the near field).
detective quantum efficiency
Describes how efficiently a system converts the x-ray input signal into a useful output image, inversely related to spatial resolution and SNR.
Phyllodes tumor
Diameter greater than 3 cm favors malignant potential for phyllodes tumor.
Twin peaks sign in twins means
Dichorionic, see a triangular shaped extension connected to a linear band.
Esophageal varices on esophogram
Different shape based in inspiration and patient positioning
Excessive aluminum in. The sulfur colloid kit
Diffuse lung uptake, larger particles. For reticuloendothelial cells, get trapped in lungs.
Loeffler's endocarditis on MRI
Diffuse subendocardial enhancement 2/2 eosinophils
Digital vs film
Digital has the potential to have lower dose relative to film bc of post processing options. Major determinant of spatial resolution of digital images is the pixel size and spacing (pixel pitch) Increased pixel density -better spatial resolution Decreased pixel pitch -better spatial resolution (less distance btw pixels the better) Plain film may have better spatial resolution than digital, bc they don't have the limitation of individual units (pixels)
Which is not an advantage of digital mammography compared to screen film mammography?
Digital offer less radiation, more manipulation, CAD; but less spatial resolution (7 lp/mm vs 15 lp/mm in screen film)
Cecal bascule
Dilated cecum in an ectopic position in the middle abdomen without mesenteric twisting
Oriental cholangitis
Dilated stones with rigid dilated bile ducts, usually left bile duct (opposite of hepatic hematogenous spread)
Partial k space acquisition
Diminishes imaging time, but also decreases signal-to-noise ratio
Direct vs indirect radiation
Direct acts directly on dna, indirect acts on water which then creates free radical that can action dna, most of human tissue is water so its mostly indirect, higher energy alpha particles have great LET and great chance of direct radiation. Indirect radiation (low LET) is promoted by presence of oxygen (OER).
Direct vs indirect inguinal hernias
Direct is medial to the epigastric vessels Indirect is lateral to the epigastric vessels
Radionuclide cystography vs voiding cystourethrography
Direct-inject tc-99 sulfur colloid into the urinary bladder with Foley catheter Indirect - tc99 DTPA or MAG3, need good renal function Radionuclide = lower radiation dose (5 vs 300 to ovaries), quantitate small volumes, ability to detect small volume Voiding cystourethrography= easier grading of reflux, can see isolated distal ureteral reflux, can delineate anatomic detail Nuclear medicine one- 3 stages of reflux (mild just ureters, extension to prox collecting system, involvement prox collecting system with diffuse dilatation) VCUG- 5 stages (SFU grades)
The energy of a photon is related to its
Directly related to frequency, and indirectly related to wavelength
Larmor frequency
Directly related to magnetic field strength, 1 T = 42 MHz/Tesla, so 3 t= 126MHz Larmor freq.
Pulse repetition period
Distance from start of one pulse to the start of the next pulse, the time between these two pulses,that's the pulse repetition period. Pulse repetition frequency= 1/PRP (pulses/sec) PRP determines the maximum depth that's imaged. PRP determines round trip time before next pulse; distance=rate x time. PRP =1/Frame rate (the faster i want to do a frame detailing the image, the shorter the PRP) Pulse repetition frequency relates to PRP: PRF=1/PRP -increase the PRF to remove aliasing during spectral Doppler -increase the PRF to get faster frame rate -decrease the PRF to increase the depth of the FOV (also called the maximum range, which is determined by the PRP) Decreased PRF causes increased FOV and lower frame rate.
Spatial pulse length
Distance that a pulse occupies in space from the start to the end of a pulse Relates to the axial resolution of the image. Axial resolution = SPL/2; you need to decrease the SPL (decrease total length of pulse) to increase axial resolution. SPL= 2 x wavelength
Eddy currents
Distortion (contraction or dilation of the image) or shift/shear. Generated when gradients are rapidly turned on and off. Most severe with DWI pulses. Fix- Optimizing the sequences of gradient pulses.
Sestamibi scan
Distribution- parotid, submandibular glands, thyroid, parathyroid, liver, and heart. Some can go to choroid plexus. Single tracer delayed scan done at 1-2 hrs.
After you find thyroglossal duct cyst
Do ultrasound to look for normal thyroid tissue, and also do a I-123 or Tc-MIBI to look for other spots. If you see nodule within cyst (papillary cancer)
Uniformity test in nuclear medicine
Done daily Extrinsic= with collimator in place Intrinsic= without collimator
Lecompte maneuver
Done for d-transposition of the vessels, with pulmonary artery infront of the aorta. This reduces kinking on the coronary arteries. Most common complication post op is obstructed coronaries.
Differences in acoustic impedance
Drives reflections
Parathyroid scans
Dual phase—> tc-sestamibi, 10mins and 3hrs, adenoma will retain at 3hrs, normal gland will wash out, relies on mitochondria and blood flow (adenoma have both increased) Dual tracer—>give thyroid/parathyroid tracer (sestamibi or thallium 201) then give thyroid only (i-123 or pertechnetate) then do subtraction. anything left is parathyroid adenoma. BTW-Tc99m-pertechnetate is trapped but not organified in thyroid (unlike I123 and I131). Any focal uptake of lymph node or breast on MIBI (get u/s or further uptake, its abnormal always)
Chemical shift artifact
Due to fat water interface, fix by increasing the receiver bandwidth and increasing the gradient strength, lower magnet strength also.
Hereditary hemorrhagic telangiectasia
Due to its high sensitivity and ability for shunt calculation, transthoracic contrast echocardiography is the recommended study for initial screening for pulmonary AVM in the setting of HHT. Tc-99 MAA is the nuclear medicine shunt study, if you see uptake in the brain; its not as sensitive.
Inhomogeneous fat suppression
Due to local field inhomogeneity, like metal inside knee , fix by using STIR, especially in setting of metal Shimming- actively improve field homogeneity, messing around with the machine to make sure field is homogeneous.
Urethral cancer in females
Due to recurrent UTIs, most common cancer is actually adenocarcinoma (60%)
Double aortic arch
Due to remnant 4th right and left branchial arches.
Spin echo
Duration=TR X phase matrix x Nex Takes a long time, the TR is the interval between 90 degree RF pulses. The TE is the time interval between the 90 degree RF and the receipt of the echo. Because a line in k space is filled at each TR, the TR contributes to the duration of the sequence. Long TR are the reason a tru spin echo is historic.
Radiation induced malformations
During week 2-8 of embryo, during organogenesis. Unlikely at doses less than 0.15Gy
Morquio syndrome
Dwarfs, oval shaped vertebral bodies with anterior beak, wide metacarpals bones with proximal tapering.
Galiazzi and Essex-Lopessi fractures
EL—>comminuted Fx of the radial head with dislocation of distal radio-ulnar interosseous membrane. Galiazzi—> fracture of the prox radius with dislocation of the proximal ulna.
When evaluating pt with takayatsu arteritis, what is most effective thing to assess before intervention?
ESR, not recommended to intervene during acute phase/ flare up (high ESR).
In slice selection in mri
Each position in slice has diffferent frequency and phase of precession during the echo. Freq encoding gradient occur when the echo occurs Phase encoding gradient occurs after the 90 degree RF, before the 180 RF Use different amplitude phase encoding gradient for each new TR (TR is between each 90 RF pulse)
Scaphocephaly
Early fusion of the Sagital suture. Normal IQ. 80% male Cleidocranial dysostosis: scaphocephaly+lack clavicles+ Wormian bones Also known as "dolichocephaly"
Brachycephaly
Early fusion of the coronal or lambdoid sutures, one coronal or lambdoid suture results in plagiocephaly, resulting in the harlequin eye. More common in girls Associated with mental retardation Order of suture close= metopic, coronal, lambdoid, and sagittal.
3 determinants of resolution
Effective focal spot size (actual focal spot x anode angle), motion, and detector
Prostate cancer spectroscopy
Elevated Cholin +creatinine/ citrate ratio ; citrate is normally produced in normal Protate. Choline is in cell membranes.
choriocarcinoma
Elevated hcg
Dermoid vs endometrioma weird cancers formed
Endometrioma - if large , >9cm and older woman, can get clear cell adenocarcinoma Dermoid- if large, >10cm, and older woman can get squamous cell carcinoma
Cancer types with endometriomas and dermoids
Endometriomas can convert to clear cell adenocarcinoma Dermoid can convert to squamous cell carcinoma. (Older than 50, size >10cm)
Entrance skin dose vs air kerma
Entrance skin dose tends to be 50% more than air kerma.
The average skin dose in relationship to air kerma
Entrance skin dose tends to be 50% more than the avg air kerma
Eovist to differentiate FNH vs hepatic adenoma
Eovist will show (20 min delay) on FNH, but it will not on hepatic adenoma as it doesn't contain bile ducts. Hepatic adenoma have greater risk of hemorrhage/rupture if in females, but greater rate of HCC (5-10%) in males (b catenin mutation). Surgery if more than 5cm bc of risk of hemorrhage.
Red marrow conversion order
Epiphysis and apophysis first, then diaphysis and finally metaphysis. Usually extremities first.
Box shaped heart with decreased vascularitty
Epstein's anomaly, displacement of posterior valve into the ventricle.
PE vs Compton scatter in soft tissue
Equal in 25kEv in soft tissue, why mammo used lower kEVs, so PE dominates below 25kEv. By using soft xrays you can get maximum image contrast. Compton relates to noise, PE to image contrast. PE Z3/E3, Componton 1/E
Matrix size is 64 x 128. How many times is the echo sampled in spin echo imaging?
Essentially asking how many freq encoding steps, bc with spin echo the freq encoding step occurs at same time as the time to echo, and it'll be bigger then that phase encoding step.
MQSA facility checkup time interval
Ever year
ACR and American cancer society on CT colonography
Every 5 years for normal risk individuals. In high risk patients, colonoscopy is the recommended tool
How often should a sealed source be tested?
Every 6 months
Radiation dose
Expressed in Joules/kg or energy per mass Power is expressed in Joules/ sec or energy per time
Extralobar vs intralobar sequestration
Extralobar in kids, less common, has own pleura covering, drainage is systemic, extra has extra associations - heart, diaphragmatic hernia, vertebral anomalies, etc Intralobular in adolescents, presents late, doesn't have its own pleura covering, not associated with extra congenital stuff, drains into the pulmonary veins.
PKAN
Eye of the tiger in the bilateral globus pallidus, secondary to iron (low signal on FLAIR and GRE).
Hemochromatosis on MRI
FAT-drops signal on out of phase (2.2 sec TE) IRON- drops signal on in phase (4.4 sec TE) Primary-pancreas is also t1 low Secondary-spleen (spares pancreas) is also t1 low
If MRI is not possible, what's second best study for spinal osteomyelitis
FDG PET/CT is better than triple phase and Ga067 for spinal or any type of osteomyelitis.
FNH vs fibrolamellar
FNH has bright T2 scar and late enhancing scar; fibrollamelar scar does neither
Pixel(voxel)
FOV/Matrix= Pixel or voxel
8 Factors Affecting Spatial Resolution in fluoro
Factors Affecting Spatial Resolution 1. FOV: smaller FOV→ better resolution 2. Focal spot size: usually not an issue unless you get the anatomy away from the image receptor 3. Image Receptor Limitations: FPD : Detector Elements II : TV 4. Motion and temporal factors→ motion creates ghosting 5. Dynamic range: only an issue for II systems→ variability in very dense or very transparent objects 6. Pixel binning: binning increases pixel size→ reduced spatial resolution (but improves SNR) 7. Frame averaging: increases SNR, but more susceptible to blur 8. Pulsed fluoro: less motion artifact (better spatial resolution in moving objects) and overall less dose
Neonatal protective factors with posterior urethral valves
Factors s that maintain renal function include a reflux, urinoma or urinary ascites, this prevent superdistention of the urinary bladder, its sort of a protective mechanism.
Klippel-Fleil syndrome
Failure of cervical segmentation at multiple levels , associated with short neck and low hairline. Limited cervical motion. Increased risk for renal, spinal cord, inner/middle/and outer ear abnormalities. Can be differentiated from surgical fusion by the narrow AP dimension of the vertebral bodies.
left ventricular noncompaction
Failure of trabecular compaction in the developing myocardium 2.3:1 ratio can lead to cardiomyopathy and arrhythmias
Nissen fundoplication
Failure-telescoping GE junction through the wrap, recurrent reflux is indication for failure Short esophagus- hiatal hernia thats fixed/nonreducible, and greater than 5cm Wrap failure= >2m of narrowing.
Zencker's diverticulum
False diverticulum, herniation of mucosa above the cricopharyngeus Posteriorly, z is the last word on alphabet so its posterior Pulsion diverticulum Will not empty unlike a traction diverticulum, bc it has not muscle to push out.
Dixon fat suppression
Fat and water have different resonant frequencies, so different surrounding environments Start with 90 RF, then water and fat inphase at t-0, then water and fat as time progresses will be in opposite directions, leading to out of phase at 2.2 relative to RF pulse, and then at 4.4 secs the fat caught up to water and they are in face. If we use an echo when fat and water are out of phase (at 2.2secs post RF) then voxels that have fat and water will have zero echo, conversely if we waited 4.4 secs voxels with fat/water would have large echo. Only for gradient echo sequences Uses principle that fat and water have different precession frequencies within the same voxel . Water image= (in phase+ out phase)/2= water (good for post contrast fat suppression) Fat image= (in phase + out phase)/2= fat
Lipomatous hypertrophy of the interatrial septum
Fat between the interatrial septum, usually dumbell shape as it spares the fossa ovalis. Lipoma is encapsulated and doenst respect the fossa ovalis. Arrhythmogenic right ventricular dysplasia would involve the right ventricle and maybe the interventricular septum, with fat noted about its walls.
Parsonage-Turner syndrome
Fatty atrophy in distributions of multiple nerves (suprascapular nerve and axillary nerve) due to idiopathic involvement of the brachial plexus.
Leg-Perthe's
Femoral head osteochondroses (flattening, sclerosis indicative of osteonecrosis) 4-10 yo white boy Femoral head
NRC for pregnant patients
Fetal dose cannot exceeds 0.5 rem / overall time Fetal dose cannot exceed 0.05rem/month during pregnancy Dosimeter is worn under lead apron at the abdominal level
Pediatric cardiac masses
Fibroma-usually intramyocardial, lateral ventricular wall, low t1, low T2, Bight post gad enhancement Myxoma-usually left atria, bright T2, variable enhancement Rhabdomyoma-usually left ventricle, , no enhancemnt
Retroperitoneal fibrosis
Fibrosis is gallium avid and PET avid. IgG4 related
Mazabraud syndrome
Fibrous dysplasia occurring with intramuscular myxomas(low t1/highT2 signal foci).
Quality control for gamma cameras
Field uniformity-daily (if using collimator-gotta wear uniform everyday) 2-5% is allowed (1%if using SPECT) Uniformity is done with a "flood test", using Na99mtCo4 or Co57 source to perform the flood. Recommended counts for both extrinsic and intrinsic range between 5-10 million . Extrinsic (with collimator) done daily. Intrinsic (without collimator) done weekly. Energy window: daily-symmetric window centered at the peak energy used in imaging test. For Tc use a 20% window centered at 140 kEV. Image linearity and spatial resolution: use lead bar phantoms , between collimator and Co57 sheet. Done weekly. Center of rotation: test done with 5 small 99mTc point sources along the axis of rotation. Axis should be straight. Done monthly.
Fill-factor in DR/CR
Fill-Factor: the area of the detector that is sensitive to x-rays in relation to the entire detector area Higher fill factor→ more efficient detection DR systems→ the electric field shaping allows for a fill factor of nearly 100% This is not seen with indirect (CR) systems → lower fill factor and thus lower detection efficiency detector quantum efficiency is therefore better in direct than indirect systems as well. better DQE the less radiation you need to maintain your signal.
De quervain's tenosynovitis
First extensor (dorsal) compartment. APL and EPB (abductor pollicis longus and extensor pollicis brevis) , usually first time mom holding baby.
Fetal dose
First two weeks (implantation)=50-100 mGy may cause fetal loss, all or nothing. 3-8th week- >100mGy will result in congenital malformations. 9-15 weeks, most vulnerable time, 100-200mGy assoc with reduced head circumference and retardation Fetal thyroid doesn't work until 8 weeks, can receive I-131 prior, after that its toast. fetal dose below 50mGy will increase cancer risk, but thats it. 10mGy during first trimester can result in 3.5 times increase in likelihood of a childhood cancer.
Fetal dose death
First two weeks , more than 100mGy Consideration also should be considered if btw 2-15 weeks and dose greater than 50mGy, not first two weeks or after 15 weeks. 10mGy during the first trimester increases cancer risk by 3.5x lifetime.
Severe pancreatitis
First two weeks is sirs/ards, but usually not infectious 3-4th week you get infections
Hypoplastic left heart surgery
First week of life-blalock taussing—> subclavian artery to pulmonary artery 3-6 months-Glenn svc to pulmonary artery, take down blalock taussing 18 months-4yrs- Fontan- ivc to pulmonary artery
Esophagogastric polyp
Fixed, thickened gastric fold that terminates in a clubbed or polypoid tip in the distal esophagus, usually secondary to benign mucosal regenerative response assoc. with erosive gastritis, doesn't change shape in different views in comparison to varices.
One of the most common and reliable findings of increased intracranial pressure
Flattening of the posterior sclera (flattening of the posterior globe).
What doesn't go through carpal tunnel?
Flexor carpi ulnaris, flexor carpi radialis, flexor pollicis brevis(intrinsic hand tendon), and Palmaris longus (if you have one).
Renal study
Flow: begins within 20 secs of injection. Flow to be seen in aorta. Decreased flow seen in renal art stenosis, renal vein thrombosis, high grade obstruction, acute rejection or pyelonephritis. Increased seen in renal aneurysm. ATN, interstitial nephritis, and cyclosporine toxicity have normal perfusion/ flow. Cortical (parenchyma): 1min , steep curve is good. Clearance (excretory): radiotracer begins to enter renal pelvis, collecting system, bladder. Should be down to half counts by 7-10 mins. time to peak : 3-5mins time to half peak: 6-10 minutes 20 minutes to peak ratio: <0.3 20/3 ratio: quantify retention of radiotrace by comparing the peak count at 20mins with the peak count at 3min (normal <0.8) Laxis renogram: true obstruction wont respond, dilated system will empty when overloaded by lasix, suggestive of a dilated by not obstructed system. Obstructed if the wasn't takes longer than 20 mins after lasix administration. diuretic t1/2 <10 mins suggests nonobstructive hydronephrosis diuretic t1/2 >20 mins suggests obstructive hydronephrosis btw 10-20 mins is indeterminate t1/2-time from peak of curve to 50% left off the peak False positive for lasix: 2/2bad renal function or dehydration, very dilated renal pelvis , full or neurogenic bladder. Suspected renal artery/: DTPA (GFR agent): a sick kidney will have decreased uptake and flow post captopril DMSA (secreted agent): a sick kidney will have increased uptakes on flow post captopril, look like an obstruction. If its bilateral up or down its nor RSA, need to see it worsen on post captopril study >10%. Renal transplant complications: ATN: preserved renal perfusion, with delayed excretion, usually day 3-5 post transplant Rejection: bad perfusion and bad excretion. Structure evaluation Tc-DMSA-preferred method in pedi Tc- GH (glucoheptonate)-more in adults All these agents the critical organ is the bladder, but with the exception of the DMSA, where the critical organ is the kidney (since it stays there).
Adenoid cystic carcinoma of trachea
Focal narrowing of the trachea, unlike TPO and relapsing polychondritis , it hits the posterior membrane of the trachea (the noncartilagenous part) mucoepidermoid carcinoma vs adenoid cystic carcinoma can be distinguished by adenoid cystic having a propensity to extend into the mediastinum, whereas mucoepidermoid does not. Mucoepidermoid also tends to involve the bronchi(indistinguishable from carcinoid) and adenoid cystic carcinoma tends to involve the trachea. adenoid cystic carcinoma is second most common tumor of the trachea (after squamous cell ).
AIDS vs PSC cholangitis
Focal strictures of teh extrahepatic duct >2cm, in PSC extrahepatic strictures rarely >5mm HIV is associated with papillary stenosis
Rate of injection per artery
For celiac, equivalent to the femoral artery (medium sized vessels) the rate is about 5ml/s Thoracic aorta-20ml/s Abdominal aorta -15ml/s Aorticoiliac-5-10ml/s Femo pop-5ml/s Pulmonary artery -20ml/s Selective pulmonary artery (r/l)-10ml/s
K edge
For incidental photons above the k edge, the incidence of photoelectric effect is 1/E^3.
RFA
For liver lesions, and kidney (AMLs) For liver lesions <4cm you are debulking, not curing. Margin of 1cm , not to burn tissue next to it, like bowel , or gallbladder Lesion should be same or smaller in size by 3 months, and definitely smaller by 6 months. CT at 1 month, if any nodular, eccentric enhancement then you can retry, CT then in 3-6 months to reassess.
Cardiac nuclear medicine perfusion quality improvement
For motion check the fine and the sonogram, to make sure there's no step off (sinogram) or motion (see bounce on the sine)
Paraduodenal hernia is due to a congenital defect in the?
Fossa of Waldeyer if its right paraduodenal (25%) fossa of Landzert if its left paraduodenal (75%) which is to the left of the ligament of treitz after a defect in the left jejunal area.
Spatial resolution in mri
Fov/matrix= voxel, the smaller the voxel the greater the spatial resolution.
Bennet fracture
Fracture at base of first metacarpal, intraarticular, two pieces, not comminuted (Rolando), the major fx fragment is pulled back by the APL (part of first extensor compartment)
Air in the MDP preparation
Free tech pertechnetate then, as the stannous ion is oxidized, this results in free pertechnetate in the stomach.
SCFE suspected,next step
Frog leg view, seen in fat black teens 10-15yo. Use Kline's line, on frog leg view (more sensitive) line should normally intersect with lateral superio femoral epiphysis from femoral neck. SCFE is bilateral 30% Leg Perthes is bilateral 10% (AVN in white kids 5-8yo) pre-slip will show negative x ray but positive periphyseal edema on MRI , so pre-slip SCFE should get hip MRI if x ray is negative.
Progressive massive fibrosis
From coal worker pneumonatoses or silicosis , large upper lobe predominant masses with calcifications. T2 dark , vs cancer which is T2 bright
Zipper artifact
From outside RF pulses entering the magnet Parallel to phase encoding direction (usually shortest direction in studies), and perpendicular to frequency encoding direction. Fix by closing the door.
Sidelobe artifact
From radial expansion of the piezoelectric crystals Echoes from elsewhere project inside anechoic structures, like the gallbladder or urinary bladder, since the radial expansion brings back echoes believed to be in the field of view. More commonly in linear transducers.
Lisfranc ligament
From second metatarsal base to the medial cuneiform Most common incident is plantarflexion (like in motorcycle stepping on the breaks)
HIV in kids
Frontal lobe atrophy
types of labral injuries
GLAD= glenolabral articular distraction, anterior inferior labral tear with assoc cartilage damage, its stable. PERTHES= avulsion injury of the periosteum with the labrum also. ALPSA= avulsion injury of periosteum with medial migration of labrum. bankart= torn labrum with periosteum disrupted. bennet lesion=extra-articular posterior and inferior labral injury , from prio POLPSA (posterior labrum and post scapular periosteum strip)
Nuclear medicine studies that show bones:
Gallium -liver>spleen Indium- spleen hotter than liver Sulfur Colloid-liver >spleen Hot spleen Think octeotride (also see kidneys) or indium wbc or technetium wbc Tc wbc has renal and GI uptake, Indium WBC has no renal and no GI. Technetium 99 WBC at 4 hrs and at 24hrs, uptake in the lungs at 4 hours (and heart) and at 24 hrs it goes away, with persistent uptake in the liver and spleen (hotter).
Bowel activity in nuclear medicine scans
Gallium 67 citrate and Tc 99 labeled leukocytes show bowel uptake Indium-111 does not show bowel uptake, any BOWEL UPTAKE IS ALWAYS ABNORMAL.
Indium vs gallium
Gallium is best for spinal infections Indium is better for sinus infectious (bc gallium is uptakes in the nasopharyngeal system), also GI (normal uptake of gallium) and graft infections, as well as post traumatic infections.
Pneumobilia in MRI
Gas is dark on all MRI sequences, on axial images, gas rises to the nondependent aspect of the bile duct and produced an air-fluid level with a meniscus. Stones are also dark but are typically dependent .
Billroth 2
Gastrectomy with gastrojejunostomy Can get afferent loop syndrome, the CBD and pancreatic duc drain into th eremnant duodenum, if you get blockage there then you susceptible to pancreatitis. Increased risk gastric CA in 10-20 yrs post op
Mentrier's disease
Gastropathy involving the fundus and sparing the antrum Bimodial distribution, in kids from CMV Albumin loss, due to lack of functioning fundus Gastric folds look like brain folds.
Survey meters in nuclear medicine
Geiger muller counter= up to 100mR/h; has "dead time" were you gotta wait for ionization to dissipate before it can respond again. Ionization chamber= 0.1-100R/h Ionization chamber used daily to check dose , should be within 5%. Dose calibration guidelines using the ionization chamber: LAG-C Consistency-daily, within 5% Linearity- quarterly Accuracy-at installation and annually Geometry- at installation and any time you move the device. ^basically geometry and accuracy are done yearly, and consistency daily. Linearity quaterly, using the ionization chamber.
Hypothalamic hamartomas
Gelastic seizures (random bursts of laughing) from hamartoma in the tuber cinerium. Precocious puberty from oversecretion of GnRH
Daily pet uniformity uses what isotope
Germanium 68 or Sodium 22
Single hot spot on bone scan
Get ct correlate. Should not be malignancy.
Chiari II malformation
Get myoelomeningocele, then drops the tonsils and the hind brain, you get banana shaped vermis (instead of bilobed ) and then the frontal lobe also is flat and get lemon shaped head (only in second trimester)
Gibbs's artifact
Ghosts near tissue edges, due to transitions in signal intensity. Looks like rings.
Gallbladder dyskinesia
Give CCK, the gallbladder will fill with contrast (not acute or chronic cholecystitis) and it will have delayed excretion, less than 35%.
Brain nuclear medicine studies for ischemia
Give diamox(azetazolamide which is a vasodilator first), then give the perfusion tracer (maybe DTPA), AREAS WHICH HAVE ALREADY MAXED OUT THEIR AUTO REGULATORY VASODILATATION (THOSE AT RISK FOR ISCHEMI) WILL THEM AS RELATIVELY HYPOINTENSE. )THESE AREAS MAY BENEFIT FROM VASODILATION. ISCHEMIC TISSUE LOOKS WORSE COMPARED TO SURROUNDING TISSUE AFTER VASODILATATION.
Absent of pulmonary vasculature in neonate
Given lack of right ventricular outflow, TOF and Ebteins anomaly can present with lack of blood vessels, truncus, transposition, hypoplastic left heart, and total anomalous all have pulmonary vasculature present.
Finger tumors
Glomua (hamartoma, dorsal aspect of the finger , low t1 , BRIGHT T2, painful, enhances) Epidermoid ( also like glomus can be subungal, dorsal aspect, also bony erosion like glomus, but history of trauma usually) Giant cell tumor of the tendon sheath(low T1, LOW T2, usually volar aspect, susceptibility of GE, usually first 3 fingers) Fibroma (low t1/T2 usually first three fingers, WILL NOT BLOOM ON GE, also tends to hit the flexor aspect)
Glomus tumor vs giant cell tumor of the tendon sheath
Glomus is low T1, high T2, and avidly enhancing, usually within subungal /periungal region. These tumors avidly enhance homogeneously. Giant cell tumor of the tendon sheath have variable T1/T2 signal, and are usually associated with a tendon. Mucoid or epithelial inclusion cysts show peripheral enhancement. The treatment for glomus tumors is surgical excision.
Cochlear promontory mass differential
Glomus tympanicus tumor, congenital cholesteatoma (acquired is in Pruzacs space, congenital however tends to be medial to the ossicles more so than at the cochlear promontory), and aberrant internal carotid artery
Somatostatin receptor tumors
Glucagonoma, gastrinoma, carcinoid, paraganglioma are positive on In-111 penteoctride However insulinoma and medullary thyroid cancer usually don't pick up on somatostatin nuke tests, even though they are neuroendocrine Octeotride sucks for insulinoma and medullary thyroid scans. I-123 MIBG is better than octeotride only for neuroblastoma and extra adrenal pheos.
film screen
Good spatial resolution, poor contrast, more suspcetible to changes in mAs or kvp.
Grades of renal trauma
Grade 1 :non expansive subcapsular hematoma or contusion Grade 2: <1 cm lac Grade 3: >1cm lac without colllecting system extension Grade 4: lac with involvement of collecting system and urine leak, or involvement of the pelvic renal vessels with active extrav Grade 5: shattered kidney
Renal trauma classification
Grade 3: >1cm laceration Grade 4: collecting system invovlement Grade 5: shattered kidney, or renal art/vein involvement
Entry slice phenomenon
Gradient echo Flowing blood has higher signal at entry of 3D slab, lose signal over course of flow (due to increased saturation); reason aorta on top is bright (by diaphragm) and dark on the bottom (pelvis). Can be fixed with saturation bands (remove slice phenomenon). toF is a gradient echo sequence which uses the unsaterated spins to make images
Bright blood MRI
Gradient echo (less 90 RF pulse) such as steady state free precession frequency, where the jet of regurgitation is dark.
Gradient vs spin echo images
Gradient echo pulse sequences were designed for fast scanning. They achieve this using partial flip angles which tip the longitudinal magnetization by less than 90 degrees towards the transverse plane. Bc longitudinal magnetization can recover faster with a partial flip angle, the TR can be decreased, reducing scan time. The penalty is decreased T1 weighting.
Gradient vs spin echo
Gradient has shorter TR (so shorter acquisition time) Gradient is more sensitive to magnetic field inhomogeneities and magnetic susceptibility, and decreased SNR.
Pancreatic serous cystadenoma
Grandma lesion, head of pancreas, multiple small cysts, central scar, central calcification (grandma is at the head and center of the table)
Posterior superior impingement
Greater tuberosity and the anterior superior labrum get hit and damage the infraspinatus and post fibers of the supraspinatus. This is secondary to abduction, like in pitchers and swimmers. It's best seen in ABER.
Fibrous dysplasia
Ground glass cortical expansion, sheperd's cook deformity (Coxa Vara) Painless No periosteal reaction Mccune Albright-polyostotic fibrous dysplasia. early puberty, cafe au lai spots Mazabrouds- myxomas in skin (low t1, high t2) and fibrous dysplasia; anything myxoid will have high signal on t2.
Osteochondroma malignant features
Growth in a skeletal mature patient, cartilage cap >1.5cm, focal destruction with lucent foci within the interior of a lesion.
High grid ratio
H/D (height over diameter ) More rejections of Compton scatter —> better contrast —> better contrast to noise ratio Higher Bucky factor Higher dose to patient More sensitivity to grid cutoff
Grid ratio
H/d, 5 in mammo and 10 in general radiography
Pcp
HIV, ggn and cysts (pneumatoceles)
Mid-Aortic Syndrome Triad?
HTN, Claudication, renal failure Young patients Spares aortic bifurcation and iliac vessels Not related to vasculitis or atherosclerosis May be in utero causes
HU and keV
HU related to attenuation of a material HU-1000 X (attenuation of material-attenuation of water)/ attenuation of water. If you decrease kEV from 140 to 100 youre closer to getting more PE than Compton scatter, so you absorb more, at 140 keV you get 100 HU, at 80 keV you get 400 HU. Same reason beam hardening degrades motion, bc you prevent low energy photons (same as doing it with too much filtration) which leads to loss of P.E., increasing avg energy and in the general lower HUs.
HU and KVP
HU values tend to increase with decreases in kV (bc of greater P.E.), seen more with higher Z values (P.E.=Z3/E3)
Magnification using the II (fluoro)
Halfing the input field would cut the image brightness by 1/4 of original brightness; this is electronic magnification. To compensate the input of the image intensifies radiation is quadrupled to compensate for reduction in juice. More radiation=more dose. Now you decreased the input by 1/2 and the output phosphor didn't change, so you essentially used magnification.
Lateral resolution in ultrasound
Has to do with beam width, can affect it by decreasing beam width to be able to tell an object with each single beam, increasing focus also decreases beam width. Decreasing line density also decreases beam width (how many lines of the ultrasound probe are activated at a time). the lesser the depth the greater the interphase btw near and far field, and so the better the lateral resolution. Spatial pulse length is not for lateral resolution, rather its for axial resolution.
Causes of asymmetric IUGR
Head size preserved, due to third trimester insult Big 3= high BP, preclampsia, Ehler Danlos
Hepatic mass in pediatrics
Hemangioendothelioma associated with neonatal chf, can calcify, elevated egf(endothelial growth factor) Mesenchymal Hamartoma is cystic Hepatoblastoma is elevated afp, can calcify, associated with hemihypertrophy syndromes including Wilms tumors, kids present with precocious puberty.
Phyllodes tumor spreads via what 10% of the time (hematogenous or lymphangitic)
Hematogenous
Hsv in kids
Hemorrhagic infarcts, encephalomalacia(hydranencephaly)
Richter hernia
Hernia containing only one wall of bowel. This does NOT obstruct, but has a higher risk for strangulation.
Extramedullary hematopoiesis
Heterogeneous fatty soft tissue masses in the axial skeleton.
Scleroderma associations
Hidebound small bowel on upper GI, NSIP, patulous esophagus .
Well counter characteristics
High efficiency Overwhelmed at counts >5000/sec Uses a PMT Used to count small amounts, therefor used in wipe tests (ahead of Geiger muller which uses a gas chamber).
Focal spot with mAs and KVP
High mAs, low kvp= wider focal spot High KVP, low mAs= narrower focal spot
Wilsons disease in brain
High t1 in putamen and globus palladi as well as thalamus, high t2/flair in the putamen, thalami and brainstem.
Nonketogenic hyperglycemia in brain
High t1 low t2 signal mostly in the putamen as well as the caudate, can also involve other regions of the basal ganglia.
What's the strategy to lower patient dose in fluoroscopy
Highest tube voltage (kvp) that will allow the best resolution, bc low kvp will need to increase mAs and this will increase patient dose.
Hind foot valgus vs varus
Hind foot valgus- Landi- talus slides down , angle btw talus and calcaneus is wider, nose down appearance fo the talus on the lateral. Hind foot varus- narrowing of the angle between the talus and calcaneus.
Synovial sarcoma
Histologically resembles synovial tissues, but doesn't necessarily arise from synovial tissue. Typically occur near a joint or within a tendon sheath. Commonly around popliteal fossa. T1 iso to low compared to muscle. T2 high signal. 1/3 can have mineralization (low signal internal foci). Heterogeneous contrast enhancement.
Pixel size and spatial/contrast resolution
Holding matrix size constant and decreasing fov will decrease pixel size. This increases spatial resolution but decreases contrast resolution (less photons per box) Holding matrix size constant and increasing fov will increases pixel size. This decreases spatial resolution but increase resolution (more photons per box).
Endometrioma
Homogeneous low level internal echoes on ultrasound If <45 y/o and 6-9cm or bigger then endometrioma has chance to become cancer (clear cell). Most common location, uterosacral ligament. T1 bright, (due to hemorrhage), T2 dark (due to iron)
Paget's bone scan
Hot on all 3 phases
SVC syndrome
Hot quadrate sign (due to enhancement of segment iv) There's drainage from the internal mammary veins to the quadrate (segment 4), which is why its bright Budd-Chiari would lead to Tc-Sulfur colloid accumulating in segment 1 on nuc med scan (caudate).
Chemical purity test
How much Al in the Tc? <10microgram Al per 1ml
Osmolality
Human plasma is about 295mOsm/kg, isoOsm is 300 , low osmol is 600mOsm/kg and high osmolality contrast is 1200mOsm/kg
For women of intermediate risk
Hx cancer, or hx atypical ductal hyperplasia, lobar hyperplasia , 15-20% risk breast cancer you just do a mammogram, no MRI.
Stages of intracranial hemorrhage
Hyperacute (less than 24 hrs) - intracellular oxyhemoglobin Acute (1-3 days) - intracellular deoxyhemoglobin Early subacute (>3 days) - intracellular methemoglobin Late subacute (>7 days)- extracellular methemoglobin Chronic (>3 weeks) - extracellular ferritin and hemosiderin ItBe IdDy BiDy BaBy DoDo
Medullary nephrocalcinosis
Hyperparathyroidism, medullary sponge kidney, type 1 RTA, milk alkali syndrome Pyelonephritis will lead to cortical not medullary calcinosis
IgG4 related intracranial abnormalities
Hypertrophied IgG4 related pachymeningitis, look for this in association with other IgG4 diseases, like thyroid, pancreatitis, cholangitis, etc. will look like basal predomeinant pachymengeal enhancemnt (like TB, sarcoid Wegeners').
Hypothenar hammer syndrome vs Buerger's disease
Hypothernar hammer has invovlement of the ulnar artery, with pseudoaneurysms, Buerger's should show autoamputation, but relatively ok ulnar arttery, and collaterals.
Arteries that come off teh posterior iliac branch
I Love Sex (***********/posterior) Iliolumbar Lateral sacral Superiuor gluteal
Ovarian cancer stage
I- one or both ovaries II- pelvic organs III-peritoneum , omentum, abdominal serous a IV-liver/spleen or malignant pleural effusions
Beta minus emmision
I-131, Xenon. Excess of neutrons, replace a neutron with gaining a proton.
Mallampati
I-Entire uvula and tonsilar pillars visible II-Tip of uvula and pillars hidden by tongue III-Only soft palate visible IV-Only hard palate visible
Endometrial cancer FIGO staging
I-confined to the uterine wall II-extend to the cervix III-passed uterus but no adjacent organ invasion IV-adjacent organ invasion (bladder, rectum) and distant mets
Stages of sarcoidosis
I=adenopathy II=adenopathy and lung III=lung IV-fibrosis
II and FPD
II is limited by the tv detector FPD is limited by the detector elements as detector elements gets smaller, you get better spatial resolution, but fill factor (% sensitive to light) is decreased, so you need more radiation . larger DEL (i.e. like through binning (grouping multiple DEL together) requires less radiation, more sensitivity, but less spatial resolution.
fluoroscopy
II uses input phosphor using CsI then photodiode converts light to electrons, go through electron flux and then minification gain (output phosphor turns e into light) with smaller size than input phosphor. the output phosphor is thin (less scatter inside) which allows for improved resolution. this process increases light photons , x50times.
Sarcoidosis using FDG PET
INSTEAD OF SUGAR LOADING FOR MYOCARDIAL VIABILITY, YOU HAVE PATIENT FAST FOR HOURS, SO THEY UTILIZE FATTY ACIDS, THEN IF YOU SEE UPTAKE ON FDG pet THEN ITS SARCOIDOSIS, ITS AS GOOD AS DELAYED mri WITH CONTRAST.
Adrenal adenoma on MRI
IP-OP/IP. If signal is more than 16.5% then it meets criteria for a lipid rich adenoma. Exceptions are Mets known to contain intracellular lipid such as clear RCC and hepatocellular carcinoma which can mimic adenoma on chemical shift imaging. Also masses >4cm should not be used (like adrenocortical carcinoma).
Large amount of pulmonary uptake on thallium cardiac study
If >0.45 lung to heart ratio its indicative of worse coronary artery disease, not pneumonia or sarcoidosis.
Popliteal artery aneurysm
If Symptomatic or >2 cm , covered stent If bilateral, scan the abdomen, greater chance of AAA.
All diagnostic dose must be off by 20% and all therapeutic dose must be off by 10%.
If more than 10% off therapeutic dose, then recordable event, if more than 20% reportable event.
Fundoplication-Nissan
If more than 2cm on the barium study, it has slipped
Transient equilibrium
If the parent half-life is longer than the child half-life but is not that long, the parent and child may be in transient equilibrium. In 99Mo --> 99mTc --> 99Tc, the peak time is about 24 hours. That is, we should extract 99mTc activity from the generator once a day at the same time. Four half lives usually when it is attained , for T 6hr x 4= at 24hrs.
Employer must provide employee total radiation dose
If year exceeds .1 rem (1mSv)
Reidels thyroiditis
IgG4 related, gland is big and fibrotic (dark on MRI sequences),uptake scan are going to be decreased.
IRIS
Immune reconstitution inflammatory syndrome, youll see enhancemt and worsening t2/flair signal after antiretrovirals are given. Pml which hit u fibers rand is asymmetric will show worse edema and now enhancement.
Partial volume in MRI
Improve spatial resolution (spatial resolution is smaller voxel/pixel, voxel= FOV/matrix)
MAS in CT
In CT mAS is calculated by tube current x rotational time. So if mA is 700 and rotation 0.4, mAS=280 Miliiampere per second in CT.
HASTE vs single shot fast spin echo
In HASTE only about half of k space is acquired per TR, followed by a bunch of 190 pulses like normal fast spin echo (allows for less T2*), but HASTE decreases time by factor of 1/2. Only disadvantage is that its sensitive to small lesions.
GI bleeding
In Vito, in Vito-in vitro (inject stannous ion, collect 15 mins into a flask with technetium ), in vitro( blood is withdrawn and added to a kit with both tin (stannous ion) and Tc. Look out for free technetium (which will be seen in the stomach , salivary and thyroid glands)
Cobb angle treatments
In adolescent idiopathic scoliosis, observation is recommended for a Cobb angle <20 degrees, bracing is recommended when the Cobb angle is between 20 and 45 degrees, and surgery is recommended when the Cobb angle is >45 degrees. The greatest factors suggesting the probability of progression of an adolescent idiopathic scoliosis are spinal growth velocity and the degree of curvature at presentation.
Monochromatic spectral imaging at various voltage levels in dual energy CT imaging
In general, a beam is composed of individual photons with a range of energies. As the beams passes through an object, it becomes harder meaning the energy increases, bc the lower energy photons are absorbed more rapidly, leaving behind only the high energy photons. For a monochromatic beam, no energy change is involved.
Adrenal nodule on PET scan
In multiple series studying the ability of PET to accurately characterize adrenal nodules, activity less than that of the background liver has been shown to be strong negative predictor of malignancy.
Left bundle branch block
In nuclear medicine , use adenosine, dipyridamole or regadenosone as they vasodilation the coronary arteries, not dobutamine which is inotropic. With the left bundle branch block, your left heart in particular the septum and apex contact before the right and you get a false apical defect. To improve this since the coronaries got filled during diastole and you the se myocardial perfusion on nuclear scan, keep the coronaries open with the aforementioned drugs.
Plasma cell mastitis
In old people, get the rod like cigar like calcification from ductal ectasia
Half life of most low osmolality contrast media
In the human body, is about 2 hours.
Triple match defect on v/q scan
In upper and middle lobes its low probability In lower lobes its intermediate probability
csf leak study
In-111-DTPA vs Tech99DTPA In-111DTPA is preferred for shunt studies bc you ll need approximately 24 hrs to assess for leak (slow flow, overtime), so half life of In-being around 72 hrs makes it perfect, vs Tc which is 6 hrs. For shunt evaluation, prefer Tc99 bc you can repeat study sooner, rather than let it build up like In-111 for 3 days.
Ways to decrease Aliasing in ultraosund
Increase PRF Decrease TF, this decreases the doppler shift, which eases the NyQuil requirement for high PRF. nyquist limit=PRF/2, if you pass the nyquist you get aliasing, since its more than your set rate. ex: freq shift of 3.5kHz requires a PRF of 7 kHz to avoid aliasing.
Increasing magnetic field
Increase SNR Increase type 1 chemical shift artifact, assuming fixed receiver bandwidth (resonant freq differences btw fat and water widens) Increase susceptibility artifact Longer T1 relaxation time , stronger Bo weakens the spin-lattice interaction that causes T1 relaxation , so it takes longer Longer TR time, same desired tissue contrast results directly from the longer t1 relaxation time Faster transverse plane magnetic dipole moment dephasing, resulting in faster free induction decay aka shorter T2* times. So greater magnetic strength, more T2*.
Filtered back projection and tube current relationship to noise
Increase mA (tube current ) changes noise by 1/(square root of change), if you increase mAs by 4, you decresasesd noise by 2.
How to decrease mottle in CT
Increase slice thickness, higher mAs, KvP and soft tissue window instead of bone window.
Effects of geometric magnification
Increase the source to object distance, leads to more air kerma (energy per kilogram entering the patient) In mammography, by decreasing source object distance(with an air gap and removal of Bucky) you get the scattered photons to diverge more before reaching the receptor and hence you decrease scatter hitting receptor. However the spatial resolution decreases as the object is further from the receptor and it gets mor magnified. When sid = sod is very close then you get best spatial resolution bc the object is closer to the receptor and the points hitting the object won't diverge out as much .
Increase slice thickness in MRI
Increase transmit bandwidth Decrease slice select gradient (shallow gradient would cover more) These are two ways you select patients head, abdomen or chest to be samples, you find the transmit bandwidth which is a range of the Bo signal.
Filtration of the x-ray beam results in:
Increased beam quality, higher avg energy of photons (higher avg kEV), but diminished image contrast. Better penetration.
Magnetic field strength and T1/T2 times
Increased magnetic field strength creates fewer anti parallel protons available to relax (transfer energy to the lattice), and therefore the T1 time is lengthened. To achieve greater SNR for stronger magnetic field, increased time is needed for T1 relaxation. T2 times are independent of magnetic field strength.
Grids in mammography
Increases patient dose, Bucky factor.
Analgesic nephropathy
Increases risk of transitional cell carcinoma
Increasing patient thickness
Increases scatter Collimator decreases scatter Scatter diminishes image quality by affecting image contrast Greater kEV leads to more Compton scatter compared to photoelectric effect.
In mri decreasing field of view
Increases spatial resolution, all other variable held contestant, by decreasing the voxel size. Decreasing field of view increases aliasing artifact.
Heel effect factors
Increases with decreased anode angle, increased field size, and decreased source to image detector distance
Probability of photoelectric absorption in relationship to atomic number
Increases, Z^3
Metal artifact in CT
Increasing KV will decrease the streak artifact. Increasing reconstruction slice thickness helps reduce the metal artifact. Use of metal artifact removal software changes the artifact pattern. increasing the mAs will allow for less photon starvation narrow collimation also helps decrease volume averaging.
Signal to noise increase
Increasing field of view, signal strength, signal average (increasing the number of acquisitions), and slice thickness. It decreases with increased matrix size (which increases resolution).
T1 relaxation time in relationship to field strength
Increasing field strength leads to increased T1 relaxation times, field strength doesn't affect T2 Increased field strength increases T1 relaxation time and hence longer time to complete study bc more spin lattice interaction with increased magnet strength, so itll take longer.
Ultrasound beam frequency and near zone (fresnel zone)
Increasing frequency =. Near zone= bs /wavelength , decreasing the wavelength with increased frequency means that the near zone increases. Increases frequency increases the near zone.
Gain and power in ultrraosund
Increasing gain only increases brightness not depth of beam. Increasing power increases depth of ultrasound beam.
SNR and excitation
Increasing the number of excitation increases the SNR, known as signal averaging.
Tube voltage
Increasing tube voltage means x ray beam intensity increases to the power of two I.e. increase voltage by 2, beam intensity increases by 4.
The velocity of an ultrasound pulse
Independent of the pulse frequency, rather it depends on the type of tissues it comes into contact with (i.e . Fat slows it down and results in speed displacement artifact bc probe thinks its further away )
Lytic lesion in bone with surrounding sclerosis
Indicative of an irritating lesion Chondroblastoma, eosinophilic granuloma, osteoid osteoma, and Brodie's abscess.
Critical organ in indium studies
Indium Prostascint (actually looks for bone mets in soft tissues NOT Bone on patients with prostate cancer but no bone mets on DMP study)= critical organ is the liver Indium WBC- spleen Indium Octeotride- spleen
Test of choice for prosthetic replacement
Indium WBC and sulfur colloid —> if there is incongruency (high indium leukocyte labeled) and low sulfur colloid, 90% specific, more than PET FDG.
Indium Octreoscan
Indium half life 67 hrs, peaks at 173 and 250kev. Can be bound to octeotride, wbc, and dtpa (shunt studies) Indium pentetreotide is the most common used agent tofor somatostatin receptor imaging. Carcinoid, gastrinoma, insulinonma, small cell, medullary thyroid, meningioma, paragangliomas. Meningioma can take up TcMDP and Octeotride Normal octeotride uptake- thyroid, liver, spleen, gallbladder, bladder, GI tract. 4 hr and 24 hrs. Advantage of 4 hr is it hasn't reach bowel.
Csf imaging
Indium labeled DTPA Normal exam-> time zero-LP, 2-4 ascends to basilar cisterns , 4-24 hrs Sylvia's fissures and interhemispheric fissures, at 24 hrs should be over cerebral convexities. NPH-> will see tracer in ventricles by 4 hrs, and not within the convexities at 25 hrs. Persistence of tracer in ventricles at 24hrs. Csf leak evaluation: like a bleeding scan, must be active to detect at time of study. You image around the csf at the basilar cisterns (1-3hrs) and also image pledges (Jammed against the most), compare tracer in the pledges to serum (ratio greater than 1.5 is positive). Shunt studies: Use tc-dtpa or in-dtpa - tracer will be in peritoneum, if there's delayed tracer flow into the peritoneum (>10mins=delayed), this can mean partial distal obstruction). -can clamp the end and see if it reflexes into the ventricle, or it doesn't clear, you can think of proximal obstruction.
Indium vs technetium for CSF leak studies
Indium lasts longer, so its used to measure at around 3 days, technetium would be good to evaluate for shunt issues
Fluoroscopy frame dose
Individual frames are about 10x the dose of a single frame fluoroscopy image.
Neurostimulation from the MRI machine
Induced electrical currents leading to painful neurostimulation. People complain of pain in legs/arms where the gradient magnetic field is changing most rapidly. Fix-reduce readout bandwidth, increase the TR (allows more cool down).
Periapical cyst(radicular cyst)
Inflammation from dental caries, lucency from the apex of the tooth, you get it, not congenital
Protamine
Inhibits heparin, half life of heparin in blood is about 60-90 mins, 1g of protamine disinhibits 100 mg of heparin. so if you have 4000U of heparin left , give 40mg of protamine. Normal heparin dose= 5000 U is good avg, if weight based 100u/kg .
For VP shunt Technetium99-MDPA study
Inject into the shunt reservoir, not via lumbar puncture
Auger electron
Inner shell electron gets ionized, another drops down, emits energy but this energy ionizes another (outer shell) electron. No x-rays produced, the Aueger electron is the energy between the k shell binding energy minus the energy of the outer shell electron which was just released by the photon.
Turbo spin echo
Instead of only one 180 following a 90 degree, you do multiple 180 degrees after 90 RF, so you can fill out more rows per TR. this is turbospin echo. This decreases the total acquisition time FSE (fast spin echo), good way to get high quality T2 images)
Quality control for full field digital mammo is performed by who
Instructions from manufacturers
SONK( SINK)
Insufficiency , not ostenecrosis of the medial femoral condyle (most weight bearing )usuallyin older pea opll after me is cal surgery.
What neuroendocrine tumors don't take up Octeotride normally ?
Insulinoma and medullary thyroid cancer
Most common pancreatic neuroendocrine tumor
Insulinoma, 90% benign, <2cm 2nd most common gastrinoma- malignant, jejunal ulcers (zollinger Ellison syndrome), associated with MEN1. Nonfunctional tumor= 3rd most common, big and calcified, malignant ! Usually mets by time of Dx.
Asbestos exposure
Interstitial pattern looks like UIP + parietal pleural thickening. Benign pleural effusion are the earliest pleural based phenomenon.
PBC (primary biliary cirrhosis)
Intrahepatic involvement only, not extrahepatic (normal extrahepatic ducts) Ursodeoxycholic acid is the treatment of choice Antimitochondrial DNA, usually middle aged women
Mottle
Inversely related to slice thickness, the bigger slice thickness the less the mottle. 1/(square root of slice thickness )
How to position patient to biopsy adrenal gland
Ipsilateral side down will restrict diaphragmatic motion, compress the ipilateral lung, and decrease ipsilateral tidal volume. Minimize pneumothorax for biopsies in the upper abdomen. Risk of pneumothorax increases in the prone or contralateral side down positions, by both increase excursion of the ipsilateral lungs.
Electronic Magnification
Irradiate smaller area of input phosphor ABC increases dose to maintain constant brightness -> dose increase of 1.4-2x per setting (less than with geometric magnification) May improve spatial resolution (II -mainly limited by quality of display TV; FPD - may decrease binning) Increases air kerma but not KAP (bc you radiating a smaller part but you increased radiation to make up for this) Focal blur spot is not increased on receptor in electronic magnification compared to geometric magnification In essence you have less minification in electronic magnification
Spleni vein thrombosis associated with what in stomach?
Isolated gastric varices
Types of atoms
Isotope=same protons Isotone=same neutrons Isobar=same protons+neutrons Isomer=same protons and neutrons (but same % of each), but energy states are different. 99mTc—>99Tc and releases a gamma ray. Mo99---> T99m occurs via Beta minus decay, the Moly has excess neutrons and you gain a proton (isobars bc the atomic mass doesnt change) and release an electron in process to turn to Technetium. The Techenetium stays as T99m- metastable state, before its nucleus which still has remnant free energy from isobaric transition releases the 140 kEV.
If spin lattice interactions decrease what happens to T1 relaxation
It increases, bc you loose the kick to regain longitudinal relaxation, less giving off of energy to the lattice by the atoms, so it takes longer for T1 longitudinal magnetization to return. Fat has alot of spin lattice interactions compared to water, so it returns longitudinally faster.
Iterative vs filter back projection CT reconstruction
Iterative can correct for noise, and so can use a lower dose.
KAP and air kerma
KAP is distance independent KAP decreases with collimation, bc you eliminating cross sectional area. Air kerma increases with collimation, bc you then make the automatic brightness control kick in and increase dose. KAP is stochastic Air kerma is deterministic
Kvp and mA with dose
KVP has an exponential relationship with dose, while mA has a linear, so does pitch (linear).
Fibromatosis colli
Kid looks away from lesion site, just big sternocleidomastoid.
Kvp for iodine and barium studies
Kvp for Angio study (using low volume of iodine)=70kV. Chosen to max out the kedge Kvp for barium study (using higher volumes of barium)= >100kV. Chosen to max out penetration.
Best view on angio for aorta
LAO (see branch best) remember LAO is in relationship to the II, best for common iliac bifurcation is contralateral oblique, best for common femoral is ipsilateral oblique.
coronary origin anomalies
LCA from the right coronary sinus, always needs to fix, RCA from the left coronary sinus (fix only if symptomatic) ALCAPA- Left coronary from the pulmonary artery, causes steal syndrome when the pulmonary pressure drops. babies usually present at 1-2 months when theres more drop in pulmonary pressures, resulting in a left-to-right shunt. also called bland-white-garland syndrome. myocardial bridging- can narrow during systole coronary fistula- connection btw coronary and cardiac chamber or great vessel. Usually RCA into right cardiac chamber. If you see crazy giant dilatation of the coronaries think about this.
Posterior enhancement
Lack of attenuation of the ultrasound beam posteriorly and attenuation correction artifact (brightness gain distal to the cyst as the machine does this automatically to tissue that's far, and the tissue behind the cyst benefits from this "time gain compensation" therefore).
Kidney and ureteral developmental associations
Lack of unilateral kidney= increases risk of unicornuate uterus
Most common presentation of gallbladder carcinoma
Large heterogeneous mass enhancing mass replacing the gallbladder, bc its usually a symptomatic for so long it has time to grow and grow.
Os odontoideum
Large ossicle that lies int he space normally occupied by the odontoid process. It's separated from the hypo plastic odontoid by a gap. Fixed to the arch of the atlas, and moves with it on flexion and extension views.
types of methods to stop the blood in IR
Large vessel permanent- coils, amplatz occluder large vessel temporary- gelfoem pledget/sheet, autologous clot small vessel permanent- particles, liquid sclerosants, thrombin, ethiodol small vessel temporary- microspheres, gel foam powder
Dielectric artifact
Large-scale signal non-uniformity. Shading often near center of field of view. Origin: Variation in tissue conductivity. More prominent with higher field strength scanners (e.g., 3T) with ascites, obese patients. The wavelength of the MRI RF excitation pulse becomes comparable in size or smaller to the human torso width. Solution: The placement of dielectric pads, which contain fluid that increase the electrical conductivity near the patient, is routinely used to remediate dielectric effect-based artifacts to some degree, or use weaker magnet.Also improved with parallel RF transmission (each coil sends an independent RF pulse).
Segund sign
Lateral to the lateral tibial plateau, 90% associated with ACL injury .
Increasing slice thickness in post processing CT
Leads to decreased noise, more photons per voxel, increased volume averaging artifact, and decreased resolution in the z-axis; dose doesn't change in postreconstruction.
Increasing voxel size in MRI
Leads to increased signal intensity, bc there are more protons now samples, so more protons contribute to the field Noise is independent, noise on MRI depends on receiver bandwidth and the RF coil characteristic. Unlike in CT where when you increase signal strength you decrease noise(mottle)
Gadobutrol (gadavist)
Least likely to cause NSF (least toxic, bc it creates the most stable chelate).
Rou-en-Y gastric bypass
Leave a small gastric pouch, do a gastrojejunostomy, connect the afferent loop of bowel to the jejunum as well Potential for gallstones and internal hernias
Bronchial artery
Left bronchial artery arises from descending aorta, can treat via IR with 3mm or greater size. Dont use coils, might have to reintervene, use particles).
Chordoid glioma
Lesion found in the anterior third ventricle. It's avidly enhancing. Can cause mass effect on the hypothalamus and optic chiasm (homonymous heminaposia).
Increased receiver bandwidth
Less SNR, more mismapping artifacts (chemical shift and or susceptibility) and TE also decreases. TE decreases bc broader bandwidth increases the amplitude of the readout gradient which allows for faster sampling of the MRI signal.
Improved ultrasound axial resolution
Less SPL the less axial resolution. (spatial pulse length) by decreasing frequency you increase wavelength, ---greater dampening of the transducer elements, which increases frequency), and broader bandwidth pulse(increases dampening) More
Renal masses in pediatrics
Less than 1 think mesoblastic nephroma (heterogeneous mass, looks like RCC really), or nephroblastomatosis (persistence of mesonephric rests past 36 week, will show up as big kidneys with surrounding rind) Wilms cannot occur before 2 months, usually at 2 y/o Multicystic nephroma (Michael Jackson lesion, at 4-6 yo and older women, its cystic and it likes to invade into the collecting system)
Incompetent cervix
Less than 2.5cm in length
Post I131 therapy
Less than 7mR/h at 1 meter, or less than 33mCi residual activity, can go home. I131 dose for cancer: Thyroid-100 Nodes+thyroid-150 Distal mets-200
Characteristic energy of photons (like the tungsten target)
Less than the k shell energy , bc its the difference btw the k shell electron and the outer shell electron replacing it. So characteristic energies are always lower than the k shell energy of the anode target.
Lucent metaphyseal bands in kids
Leukemia, neuroblastoma, rickets or scurvy, infection.
Leukoplakia vs malakoplakia in urinary system
Leukplakia is the malignant one, asscoaited with squamous cell carcinoma not transitional cell. Malakoplakia also presents as a mass filling space but is not premalignant.
Lewy body dementia vs Alzheimer's on PET
Lewy body like Alzheimer's will show decreased parietal and temporal lobes, but Lewy body dementia also shows decreased uptake in the occipital lobe which is not seen in Alzheimer's .
Santorenocele
Like choledochocele essentially, associated with pancreas divisum, drains the superior minor ampulla from the body/dorsum of the pancreas. Santorene-Superior duct
Geometric magnification and II
Like electronic magnification (zoom due to decrease light hitting the input phosphor) , geometric magnification increases spatial resolution , although technically the SOD being closure creates more blur, there's follow up with a smaller focal spot (0.1 vs 0.3 in mammo) which leads to improved spatial resolution overall.
Epidermoid vs choroid plexus granuloma
Like epidermoid, low t1, high T2, nonenhancing , restrict diffusion Best idea is choroid plexus is bilaterality.
Use of SPECT brain for ICA-ECA bypass
Like in pfts with moyamoya, give ACZ and if there's paradoxicAL reduction in tc99 hmpao, they will benefit best
Dose limit for unrestricted area
Like secretary or hallway , <0.2mrem/hr
Synovial sacroma
Likes the periphery, usually young people, enhances, has calcification, next to but not within synovial joints. T2 triple sign of signal. Likes to calcify and ossify a lot. Soft tissue calcification + bone erosion = synovial sarcoma (most soft tissue lesions don't mess with bone) Most common malignancy in young persons foot, toes, lower extremities Painful
Congenital lobar emphysema
Likes the upper left lobe , expands, have to do surgery to fix, unlike Swyer James which is post infection and results in low lung volumes and bronchiolitis obliterates (air trapping).
Skeletal dysplasia
Limb absent-Amelia Limb is almost absent- meromelia Hands/feet (distal limbs) are short- acromelic Forearm or lower legs are short (middle limbs)- mesomelic Femur or humerus (proximal limbs) are short- rhizomelic Short all over-micromelic Me so is in the middle, Acro is distal and the other one is the other one. Main dwarfs, like achondroplasia (fibroblast growth factors receptor problem, rhizomeric, short Pericles, tombstone vertebra) are rhizomeric.
RCC staging
Limited to kidney <7cm stage1, > 7 stage 2, inside gerottas fascia with renal vein hit 3a, ivc 3b, supradiaphragm ivc 3c, outside gerottas fascia stage 4.
Gauss line
Line that no one should cross around MRI if they have contraindicated material like pacemaker, cochlear implants, etc.
Activation array types
Linear activation=one or a set of piezoelectric crystals Phased array= all simultaneously but activated differently(some more than other); allows for steering, and also to adjusts focal distance (narrowest part of beam). Phased array transducers achieve wide FOV despite small footprints, which lets you perform cardiac imaging with a probe that fits between ribs.
Renal tubular ectasia
Linear filing defects in the medullary region ( papillary region)
Regularity agencies use what model to predict lowest radiation level exposure for biological effect
Linear, non threshold
X ray beam intensity
Linearly related to tube current (mAs) and exposure time .
Technetium HMPAO and ECD
Lipophilic agents used for brain death studies, usually taken as static images after 20 mins Tech 99 Pertechnetate is given (injected via bolus) and calculated at 3 seconds frames, its blood bound and doesn't cross the BBB, but would be picked up in the ICA and CCA, MCA.
Right heterotaxy
Liver, no spleen Two fissures on left lung Reverse ivc and aorta More congenital heart defect association than left sided heterotaxy
Critical organ
Liver-prostascint, sulfur colloid, I-131 MIBG Kidney-DMSA, Thallium Bladder- I123 MIBG, MAG3, DTPA, MDP (bone scan) Spleen- Octeotride, In-WBC, tagged heat tx RBCs Colon-sestamibi, gallium, oral sulfur colloid Gallbladder-HIDA agents (Tc-99m mebrofenin and disofenin), Tc99-Tetrofosmin and sestamibi (cardiac agents) Stomach-pertechnetate Heart-Tagged RBCs/
Technetium 99 sulfur colloid scan
Liver>spleen>bone marrow If there's liver issues (I.e. cirrhosis), then the spleen uptake is greater, "colloid shift" Indium-111 Also has the same normal uptake, but its spleen>liver normally give 3-5mCi for study imaging begin to be acquired after around 20 minutes, has a 2-3 min blood half life before taken up by retioculoendothelial system. the sulfur colloid gets phagocytosed by Kuppler cells in liver and reticuloendothelial cells in the spleen and bone marrow
Fibroadenoma on MRI
Lobulated enhancing mass with non enhancing internal septa Enhancing internal septa is malignancy
Penetrating ulcers
Look for a gap in the intimal calcifications Sacular morphology around the arch, usually.
TRALI
Looks like ARDS, presents 1-6 hours post transfusion.
Truncation/gibbs
Loss of info of k space through Fourier tranform. See it at high contrast interfaces (skull-brain, cord-CsI, meniscus/fluid), can mimic a syrinx in the cord. Can be seen in frequency and phase encoding directions, more commonly in the phase encoding direction. Fix - more matrix, decrease pixel size (decrease FOV, increase matrix). Penalty- increased acquisition time (basically increase spatial resolution).
Type II chemical shift artifact differentiating AML vs renal cell carcinoma
Loss of signal in periphery, leading to the India ink artifact on the lesion is indicative of macroscopic fat (AML), whereas lesions that contain microscopic fat (intracytoplasmic fat) (like RCC) would demonstrate signal drop out in center rather than just the periphery. Both RCC and AML contain intracellular fat (microscopic fat) which is what would phase out in in/out phase imaging, only macroscopic fat would give you that peripheral signal loss of signal (the India ink).
Standing wave or dielectric artifact
Loss of signal in the middle of a body part with increased RF (3T vs 1T) secondary to shorter wavelength with increased magnetic field, resulting in messed up signal, solution= switch to higher RF wavelength (1.5 T). More important at T magnets greater than 3.
System unsharpness
Loss of spatial resolution (how you can tell two lines apart) Film-size of the grain of photographic chemical Computed radiography- (CR)-size of the laser used to read the phosphor plate in the cassette reader Digital radiography-(DR)- size of the individual thermaoluminescent transistor.
breast quality control time period
Louis, Do Patient Say Penis Very Randomly? localization/accuracy (for stereotactic biopsy)-daily darkroom cleanliness-daily processor quality-daily screen cleanliness-weekly phantom image evaluation-weekly viewbox cleanliness and viewing checklist-quarterly repeat analysis-quarterly fixer retention-semiannually darkroom fog-semiannually screen-film contact-semiannually compression-semiannually
MRI characteristics of cardiac myxomas
Low T1, high T2 (due to myxoid content)
Low lying/tethered cord
Low conus (below T2), thickened film terminale (>2mm) The cord migrates down with the canal, but the canal does so faster, so it can stretch it and lead to ischemia. Associated with anal atresia Associated with spina bidifa High dimples screen, low dimples no need to screen.
Klippel trenaunay syndrome
Low flow vascular malformation Port wine nevi Bony or soft tissue hypertrophy Persistant sciatic vein Marginal vein of Servelle (superficial vein in lateral calf and thigh) Rectal cavernous hemangioma Liver or splenic angiomatosis, which are susceptible to bleeding
Adamantimoma
Low grade Osseous malignancy, predilection for the anterior tibial diaphysis, can have cortical breakthrough , and may present with fluid/fluid levels.
Fleischner criteria for incidental nodules
Low risk= <6mm, no follow up, 6-8 mm one year and consider 18-24 month follow up, >8mm consider 3 month ct, biopsy or do PET. High risk=<6mm, one year follow up, 6-8mm one year and 18-24 month follow up, >8mm consider 3 month ct, biopsy or do PET.
Most reliable T1weighted MR signal pattern for pedal osteomyelitis
Low signal in a geographic medullary distribution
Mortons neuroma
Low t1 high t2 enhancing perineural fibrosis, not an actual tumor, classically btw the third and fourth metatarsal heads, at the plantar aspect.
Paraneoplastic limbic encephalitis
Low t1, high t2/flair signal intensity within the mesial temporal (hippocampus and amygdala regions) without hemorrhage , or enhancement usually. Associated with small cell paraneoplastic effects. HSV will restrict. Seizure would not be bilaterally(and could enhance or restrict).
Giant cell tumor of the tendinous sheath (PVNS)
Low t1, low t2 (glomus body tumor is high on t2), enhancing lesion that surrounds tendinous sheath, its same as PVNS so will have blooming on GRE.
Malignant fibrous histiocytoma
Low to intermediate t2, usually in central portions of upper extremities, can calcify, will enhance Old people Spontaneous hemorrhage and bone infarcts
Low vs high osmolality contrast agents
Lower osmolal contrast agents provide less chance of hypersensitivity reaction.
Radioactive level 1
Lowest level and white in color. Shouldn't exceed 0.5mrem/hr At 1 m no detectable radiation
Collagen vascular disease
Lupus=pleuritis, pericardial effusions and pleural effusions RA= lower lung, looks like UIP and COOP. Kaplans syndrome (pleural effusions + upper lobe predominant nodules with the RA (which looks like UIP and COOP in the lower lung zones) Scleroderma= NSIP Sjorgen's =LIP Ankylosis spondylitis = upper lobe predominant fibrotic changes
Most common abnormal mediastinal mass in children (>10)
Lymphoma 90% Hodgkins, and will involve the thymus. Big mass in kid under 10, thymus, over 10 lymphoma.
Liposclerosing myxofibroid tumor
Lytic tumor with central calcs and well defined borders in the intertrochanteric region classically, can have sclerotic borders. Pits pits are here as well.
Fracture risk
Lytic, >3cm, >50% cortex involvement
Bronchogenic carcinoma lymph node level
M0-no regional lymph node metastasis M1- peribronchial or perihilar lymph nodes M2- same side mediastinal and subcarina M3-contralateral chest side , ipisilateral scalene and supraclavicular lymph nodes
The half value layer and current vs voltage
MA= current KVP= voltage The half value layer depends on voltage and is independent of current.
Technetium 99 DTPA VS MAG3
MAG3 is preferred due to higher target to background counts, and more of it is cleared in the renal collecting system compared to DTPA. MAG3 is secreted , DTPA utilizes GFR.
SLE arthritis
MCP ulnar deviation without joint space narrowing, with resolved on flat hand on PA view
malignant fibrous histiocytoma vs synovial sarcoma
MFH (or PUS pleomorphic undifferentiated sarcoma) affects older people, tends to be intm to dark on T2, and hits proximal extremities. Synovial sarcoma (close to but not in joints) affects 20-40 yo, peripheral and shows triple sign on T2 (dark, intm and bright signal).
MIBG vs Octeotride
MIBG is better for pho's and neuroblastoma, otherwise octeotride is better.
Any ovarian intracystic nodule without internal vasculature gets what?
MRI as follow up to make sure its truly a cystic ovarian lesion. If the nodule has internal blood flow then you just go to surgery.
Best spatial vs contrast resolution
MRI offers the best contrast resolution. X-rays offer the best spatial resolution. Ultrasound is better than ct and MRI for spatial resolution of rotator cuff pathology.
Soft tissue contrast by modality
MRI>ct>mammo>CR Lower kvp in mammo allows for better contrast compared to CR (mammo has to differentiate btw soft tissues with similar densities ) MRI (can tell mets a lot easier in liver than on ct for example so difference in tissue densities can be more easily seen)
Magnification in breast and lack of focal spot decrease
Magnification introduces blurring or geometric unsharpness, which if the focal spot size is not decreased will hinder image. You mitigate it by reducing focal spot size.
MUGA scan QI
Make sure the ROI is not within the blood pool or the spleen. To calculate EF= diastole count-systolic count/diastolic count -background count; if you have too much background count your denominator is decreased and you'll have a false elevated EF.
Adenocarcinoma of esophagus
Makes right angles with the esophageal wall
Myxomas
Malignant neoplasms arising from connective tissue, prefer muscle (typically intramuscular lesions) Have low to intm T1, and high T2 signal (bc of myxoid component) Mazabroud's syndrome==> fibrous dysplasia and myxomas
Milan criteria for liver transplantation
Malignant portal vein thrombosis is a contraindication (vascular invasion and extrahepatic mets are exclusion criteria) Tumor must be <5cm, or up to 3 tumors each less than 3cm. Hepatic encephalopathy and refractory varicella bleeding are among acceptable indications for liver transplants.
Choriocarcinoma
Malignant tumor of the placenta, trophoblastic only do not make villi Penetrates to the myometrium and the parametrium, then hematogenous spread Classic board is 8-10 post evacuation of a mole, you get elevated bHCG. Tx=methotrexate
Gastric ulcers
Malignant ulcers occurs anywhere, they tend to be wider than deeper Benign ulcers have a thin lucent line at the mouth (Hamptons line), and they tend to have gastric rugae up till the ulcer begins, converging on the ulcer. Benign ulcers occur in the stomach antrum and lesser curvature. Malignant ulcers occur anywhere
For women with high risk breast cancer
Mammogram and mri with and without contrast, concurrently (>20% risk, first degree relative with BRCA, mantle radiation at 10-30 yo, etc.)
High T1 signal in the basal ganglia on cirrhotic patients
Manganese or parenteral nutrition
Increased t1 signal in globus pallidus
Manganese, can be seen in liver failure patients, also patients on long term parenteral nutrition.
Type 2 endoleak
Many type 2 endoleaks will spontaneously resolve. Stability of the sac is the most important criterion. >6 month type 2 endoleaks assoc with aneurysm sac growth >5mm should be treated.
Hypoplastic left colon
Maternal magnesium and diabetes are the two risk factors enema is dx and therapeutic immature cells
Scatter in film radiography
Maximized with Higher kvP (higher Compton scatter) Larger field of view (more scatter hits the receptor) Thick parts (people) denser tissue which allows for more Compton scatter overall
Functional MRI
Measure increased blood flow measured to neural activity. FMRI depends on T2 star effects due to deoxyhemoglobin acting as contrast agent bc its is paramagnetic.
Segmental arterial mediolysis (SAM)
Media of the splanchnic vessels (celiac, SMA, IMA) turns to shit, and you get dissections, aneurysm, bleeding. No vasculitis, or hereditray.
Carpal tunnel
Median nerve, 4 flexor digitorum profundus and superificialis, and flexor pollicis longus.
Radioactive level 2
Medium levels of radiation and yellow in color. Shouldn't exceed 50 mrem /hr on surface, and no more than 1 mrem /hr at 1 meter. Any level higher is radioactive level 3.
Types of breast cancer
Medullary =round or oval breast mass without calcifications, prominent lymphoid invasion on biopsy! Usually cystic and nodular (complex cyst?) Papillary=small speculated mass with/without calcifications. Best prognosis DCIS= calcifications , linear (comedo), non linear (noncomedo-usually pleomorphic in distribution)
Multicystic nephroma
Medullary based tumor, Wilms is cortically based Usually resected. Cystic, with a capsule, young kids and older women (Michael Jackson lesion)
Medullary nephrocalcinosis
Medullary sponge kidney (most common), type I RTA, hyperparathyroidism, hypercalcinosis (hypervitaminosis D, milk-alkali syndrome), sarcoidosis, ox alumina, furosemide use.
Renal clear cell sarcoma
Medullary tumor, most common at 2 years old , likes to met to the lung and to the bones
Medical events in nuclear medicine
Meet 2 criteria 1. Wrong drug, wrong route, wrong patient, wrong dose (more than 20%) OR pt receives a dose to a part of the body other than the intended tax site exceeding by 50% or more the dose. 2. Harm the patient A. Whole body dose> 5rem, or B. Single organ dose >50rem Recordable event: whole body <5rem, single organ dose <50rem, (if more than these 2 numbers its a reportable event); must be written down and saved for 5 yrs. Reportable event: whole body >5rem, single organ dose>50rem, call ordering doc within 24 hrs, state, etc. call NRC within 24 hrs. Written letter to nrc 15days.
Most common primary to metastasize to the spleen
Melanoma
Jejunal diverticulosis
Mesenteric side, associated with bacterial overgrowth and malabsorption.
Multilocular cystic nephroma
Michael Jackson lesions, boys around 3-5 , and middle aged women. Leads to fluid filled foci extending to the renal pelvis with thickened surrounding capsule. Not solid.
Susac syndrome
Microangiopathy affecting females in early adulthood Triad of: - encephalopathy - sensorineural hearing loss - retinal artery occlusions Round T2 hyperintensities may involve gray and white matter SICRET syndrome - small infarctions of cochlear, retinal and encephalic tissue
Lower GI bleed
Microcoils or PVA particles Don't use alcohol in the lower GI tract bc you cause bowel infarct Microcoils need to be in close proximity to the bleeding vessel, pva particles don't need to be as close, they are flow directed, but less control Can do provocative Angio-squirt NO or tpA and try to make vessel you think is bleeding bleed. PVA particles 300-500 microns, smaller you can have it go elsewhere and lead to bowel ischemia.
Male pelvic cysts
Midline: Prostatic utricle cyst, connected to the urethra Mullerian duct cyst, not connected to urethra, above the prostate Lateral: Seminal vesicle cyst
Most common location for Achilles' tendon rupture
Midsubtance location (2-6cm from tendinous insertion)
MELAS
Mitochondrial Encephalopathy, Lactic Acidosis, and Stroke-like episodes Usually multifocal distirbution and stroke in a young patient.
Rheumatic heart disease valve involvement
Mitral(60-70%)>aorta>tricuspid> pulmonic
Joubert syndrome
Molar tooth, due to lack of decussation of the superior cerebellar peduncles Assaociated with retinal dysplaisa, renal and liver issues as well Batwing appearance of the superior fourth ventricle.
Technetium99m creation
Moly generator, then you milk the generator The amount of half life's to get the most Tc99m is approx 4 x t1/2, after that T99m starts to convert to its isomer T99. 4 x 6 hrs(Tc99m half life)= 24 hrs, so you need to milk the generator at 24 hrs. Purity of the eluate= Mo breakthrough 0.15microgram per 1 milligram of Tc99m. Lead shield to measure, lead shield kills the 140kEv but lets the Mo out at around 700kEv off Mo. Aluminum breakthrough = 10microgram/ml Eluate. Can get too much aluminum, which then ends up in the liver after forming a colloid mix. Can assess with chromatography. Tc 99m sulfur colloid scan +aluminum aggregation =deposit in the lungs. So if you see Tc-99 sulfur colloid in lungs think of aluminum breakthrough.
Radioimmune therapy
Monoclonal antibodies can be used with indium , for refractory non Hodgkin, first give antibody labeled with indium for diagnostic evaluation of tumor burden, then to see if biodistribution is ok. Altered biodistribution: Lungs >heart on day one, lungs>liver on day 2-3 Fixed uptake in bowel Uptake in bone marrow >25% Kidneys >liver on day 3.
Center of rotation test
Monthly SPECT cameras Assesses for offset at center of rotation Performed with 5 small Tc-99m point sources Axis should be straight Error -> looks like tuning fork (same appearance as motion)
Power doppler
More sensitive to flow, not direction of flow , robust to aliasing , less sensitive to doppler angle. Disadvantages: increased sensitivity to flash artifact(Doppler signal in non-flowing tissue resulting from transducer or soft tissue motion), slower frame rate.
Intussuception
More than 2.5 cm long, gets air enema. Usually enterocolic intussuception. Less than 2.5cm doesn't get air enema. Max pressure is 120mmHg
Urethra cancers
Most are squamous, if ureteral diverticulum (adenocarcinoma), prostatic urethra (being close to bladder )gets trasntional cell.
Pulmonary vein variants
Most common aantomic vairation is a separate vein draining the right middle lobe. Absent pulmonary vein is usually seen on the opposite side of the aortic arch, absent right pA with left sided aortic arch, absent left PA with right sided aortic arch. Absent left PA is associated with TOF and truncus (bc you have right sided aortic arch)
Aortic coarctation
Most common association is the bicuspid aortic arch associated with: turner's syndrome bicuspid aortic valve berry aneurysm rib notching (4-8th ribs), doesnt involve 1-2nd ribs bc fed by costocervical trunk
Endometrial cancer staging
Most common cause of gynecological cancer Staging is surgical Stage I: spread limited to the uterus (most common stage at diagnosis) - IA: limited to the endometrium or invasion *less than 1/2 of myometrium* - IB: invasion *more than 1/2 of myometrium* Stage II: extension to teh cervix but not outside the uterus Stage III: Spread adjacent to teh uterus - IIIA: invades serosa or adnexa or positive cytology - IIIB: invasion of vagina - IIIC: invasion of pelvic or para-aortic nodes Stage IV: Spread further from the uterus - IVA: involves bladder or rectum - IVB: distant metastasis
Testicular masses
Most common extratesticular mass is rhabdomyoasarcoma Most common intratesticular mass is germ cell (90%)
Gastric diverticuli
Most common in the cardiofundal posterior wall region, benign
Leukoplakia vs malakoplakia
Most common in the ureter and bladder (bladder>ureter) , presents with filling defects Leukoplakia is premalignant=squamous (not transitional) cell carcinoma Malakoplakia is not premalignant.
Sinus of valsalva aneurysm
Most common is on the right side annulus. If its all 3 it can give you the water tulip sign (which extends passed the sinotubular junciton into the ascending aorta, seen in Marfans).
Thanatophoric dysplasia
Most common lethal skeletal dysplasia, FGF 3 deficiency , present with short proximal long bones (rhizomeric), shortened pedicles as they descend. Jeune syndrome is short ribs which axphysiates the kids and polydactyly. thanatophoric also present with megalencephaly
Osteoid osteoma
Most common location is femur, then tibia. Most common spine location is the lumbar spine.
Left atrial myxoma
Most common nonmalignant heart Tumor in adults Rhabdomyoma most common in kids (assoc with TS), unlike fibroma (2nd most common in kids) this is T2 dark. Fibroma (second most common tumor in kids, like the IV septum) Fibroelastoma is most common tumor of the valves (mitral and aortic 80%, aorta most common, vegetation's involve the valve free edges). qevlar says best way to differentiate fibroelastoma from vegetation is presence of valve damage.
Cardiac myxomas
Most common primary cardiac tumor, low t1 high T2 due to high myxoid content; typically present in children with hypoxia (no idea why) more than with arrhythmia or emboli. Carney's complex is associated with cardiac myxomas.
Malignant fibrous hystiocytoma
Most common sarcoma, approx 25%.
Lymphoma of the small bowel
Most common small bowel malignancy, hits Peyer's patches, can then involve through mass effect the Auerbach plexus leading to focal aneurysmal luminal dilatation, in up to 1/3 of cases.
Cmv in kids
Most common torch infection Periventricular calcifications Associated with periventricular calcifications
Hepatoblastoma
Most common tumor in 0-5 yo. Associated with Wilms, AFP, and bHCG (can get precocious puberty). 50% calcification.
Ewing's sarcoma
Most commonly in the metadiaphysis , then diaphysis then metaphysis.
Talocalcaneal coalition
Most commonly occurs inferior to the sustentaculi tali, at the middle subtalar facet (not as often at the anterior or poster subtalar facet)
Cystic hygroma
Most likely on OB ultrasound showing a cystic mass off the back of the neck. T2 bright like hemangioma (will not have flow voids, and wont enhance like hemangioma) Associated most commonly with Turner's syndrome, second most common with Down's syndrome. Most common CV associated is coarctation of aorta.
Papillary carcinoma of the breast
Most likely to be associated with a cyst tubular most likely to show as a small spiculated lesion . Tubular has been prognosis (97%)
Malrotation , where is the cecum
Most of the time it will be high and medial near the umbilicus, 20% in malrotation its in a normal location
Most common cause of post transplant ureteral stenosis
Most of the time occurs at the vesioureteral junction, involving the distal ureter (90%) of cause is ischemic, the further out the ureter is from the renal artery , the more susceptible.
Mucinous cystadenoma
Mother lesion, body and tail, peripheral calcifications There can be premalignant , so need to come out Cysts are bigger than serous.
Quantum mottle relationship to mas
Mottle is inversely related to square root of the mAs. Quadruple the mAs, decrease the mottle by factor of 2.
How to improve studies with poor fat saturation
Move anatomy of interest towards the isocenter, perform shimming, apply sequences less susceptible to susceptibility artifact (STIR, spin echo with short TE and not gradient echo).
Fluoroscopic sniff test
Movement of diaphragm up during inspiration(instead of down) from phrenic nerve injury.
Mullerian, wolffian ducts and UG sinus
Mullerian-fallopina, uterus, 2/3 vagina Wolffian- seminal vesciels, vas deferens, epididymis UG sinus-1/3 lower vagina, prostate
Jaffe-Campanacci Syndrome
Multiple Non-ossifying fibromas Cafe-au-lait spots Mental retardation Hypogonadism Cardiac malformations Ocular abnormalities
Ollier's vs Maffucci's syndrome
Multiple expansive lytic lesions, absence of digits, Maffuci presents with more (phleboliths, indicative of soft tissue hemangiomas which are not seen in Ollier's) so look for extrabony calcifications Maffuci has higher risk of chondrosarcoma and sarcomatous conversion
Hot bun cross sign
Multiple systems atrophy
Enhancement on CT scan for renal lesion
Must be above 20HU, bc less than that could be due to beam hardening artifact from the adjacent enhancing renal parenchyma when describing a renal cyst (especially if less than 2cm) (called pseudoenhancement), MRI would be best then .
The hot lab door
Must be locked OR under constant surveillance
meconium aspiration syndrome
Must have meconium below the vocal cords, the diagnosis cannot be made by meconium stained amniotic fluid Rope opacities, hyperinflated lungs, barotrauma (pneumothorax), the first x ray may be normal, may take time to develop the chemical pneumonitis
Pulmonic valve in relationship to aortic valve
My PAL SAL (PAL-pulmonic ) SAL- superior, anterior, left of aortic valve
Most common tumor of the filum terminate and conus
Myxopapillary ependymoma
Most common intradural extramedullary lesion of the filum terminale/cauda equina
Myxopapillary ependymoma , can have hemorrhagic components and calcifications. Usually T2 bright, and enhancing.
Most common tumor of the conus medullaris and filum terminale
Myxopapillary ependymoma, enhancing lesion Usually 35 y/o
breast cancer node and staging
N2: ispilateral axillary and internal mammary N3: Ipsilateral supraclavicular and combination internal mammary + axillary M1: cervical nodes on whichever side, contralateral axillary or clavicular
tibial bowing differential
NF-1=ant tibial bowing, assoc. with fibular pseudoarthrosis physiologic bowing= btw 18 months and 2 yrs, lateral-bilateral symmetric Blount's= tibia vara, often asymmetric, early walking, fat/black kids; prox tibia posteromedial physeal growth disturbance resulting in deformity.
Scintillator crystals
NaI in nuclear medicine , convert photon into flash of light. Thick crystals are more sensitive but worse spatial resolution bc PMT have to be further away, harder to localize event accurately Thin crystals are less sensitive but better spatial resolution bc PMT can sit closer to the event and more accurately localize it.
Nuclear medicine instruments
NaI- well counter, gamma camera (planar imaging + SPECT) CsI- indirect flat panel detectors (FPD) for x-rays (fluoroscopy) BGO, LSO, GSO- PET Gas-filled detector- G-M pancake probe, dose calibrator, cutie pie survey meter, ionization chamber
Pyriform aperture stenosis
Narrow , less than 4mm of the nose opening. Associated with megaincisor and midline defects, like corpus callosum.
Mid aortic syndrome
Narrowing of teh aorta, in longer segmetns than lericvhe syndrome, assoc with some in uterine vaqscular issue,not due to vasculitis or atheroscelrosis, usually young patients.
Choanal atresia vs congenital piriform aperture stenosis
Narrowing of the choanal space, the oronasal passage, thickening of the vomer Piriform aperture is the narrowing of the nasal eminence, more entire to the choanal atresia, its failure of formation of the primary palate, and so you can a central maxillary incisor (which is related to medaling defects of the brain (corpus callous agenesis, and holoprosencephaly).
hepatoblastoma
Neuroblastoma of the liver, calcifications, high afp, big lesion. Usually before 5 yo 90% of the time.
bronchial artery bleed
Never use coils, use gel foam, You may need to go back. Most time angio is neg. >3mm, Tx. CAREFUL FOR HAIR LOOP LOOKING ARTERY USUALLY LOWER THORACIC /UPPER LUMBAR LEVEL (ARTERY OF ADAMKEWITZ)
Breast magnification
No grid Increases the distance btw the breast and the receptor, not the x ray and the breast Smaller focal spot Longer scan time
Breast feeding and F18 PET
No interruption required. Only interrupted for Ga67 (1-4weeks) and I-131(rest of pregnancy)
Fluid collections in pancreatitis
No necrosis = <4 weeks -peripancraetic fluid No necrosis = >4 weeks - pseudocyst Necrosis = < weeks - acute necrotic collection Necrosis = >4 weeks - walled off necrosis
Sidebranch IPMN
No resection unless its >3cm in size
Salpingitis isthmica nodosa (SIN)
Nodular scarring of fallopian tubes (usually proximal 2/3), so hits the isthmus (most medial), ampulla (next most medial) (most common site of ectopic pregnancy) Likely post-inflammatory or infectious Strongly associated with infertility and ectopic pregnancy.
Types of gynecomastia?
Nodular-round retroareolar. Dendritic -flame shaped retroareolar. Diffuse- combo of both.
3 types of gynecomastia in men
Nodular-usually less than a year, painful Dendritic- usually more than a year, fibrosis is apparent Diffuse glandular-usually men on estrogen therapy
T3 VS T4 in lung cancer
Nodules in same lobe is T3. Nodules in separate lobes is T4. Nodule in other lung is M1.
NEC in PET
Noise equivalent counts, equivalent of signal to noise ratio in PET.
Noise
Noise std is proportional to 1/square root of #photons in a pixel Increase slice thickness = increase photons per voxel (pixel in 3D, x x y x z, z is slice thickness), so you increased noise Increase DFOV= increases voxel size in the axial plane. Increasing DFOV by factor of 2 on both sides will increase the total cover volume by a factor of 2x2=4, which quadruples the total number of photons per voxel. Increases mA-s: linearly increases total #photons coming from tube, increasing dose and noise Increasing pitch=increases dose to the patient and causes X-ray tube to linger for longer over each part of the pt, also increasing mA-s.
liposarcoma
Not entirely fat, has septations, usually within he retroperitoneum.
seminomas
Not high afp, high bhcg Most common testicular tumor, best prognosis, usually 25 yo Homogeneously dark on T2, most other testicular cancers are not T2 dark. Elevated afp-nonseminoma, yolk sac Elevated bhcg-seminoma, choriocarcioma If you have mets to the pelvis, external iliac, and inguinal nodes, this is considered non region , i.e. M1 disease, bc it shoudl go to paraaortic lymph nodes, unles choriocarcinoma (hematogeneous spread)
Echo train length
Number of echoes that are read out for each TR. In essence, the more echo train the shorter the time , as more echoes are able to fill k space.
Total acquisition time in MR
Number phase encoding gradients time amount of time to get all rows (TR (Number of pulses) x (N phase encoding steps) x (NEX number of excitations, number of k space matrix collected to average together) Scan time= NEX x #slices x TR x Ny/ turbo factor
Lithium nephropathy
Numerous nonenhancing 1-2cm cysts
Pulmonary Venoocclusive disease (PVOD)
Obliteration of the post capillary venules, but with normal wedge pressure (unlike mitral stenosis, big pulmonary vein obliteration, etc) Highlight is —> bilateral interlobular septal thickening Will see other signs of pulmonary hypertension
Choroid plexus carcinoma
Occurs in children , typically around 26. Month s
Aliasing in MRI
Occurs in the phase encoding direction. Can be improved by: Increasing field of view Over sampling the data Switching from phase and frequency encoding direction Applying pre-saturation bands to areas that are not going to be sampled Of note, aliasing in 3D occurs in the x and the y direction.
Positron decay
Occurs when the nucleus emits a particle that degrades into a positron as it passes out of the atom, its the release of a proton (Z-1).
theca lutein cyst
Often bilateral/multiple. Due to gonadotropin stimulation. Associated with choriocarcinoma and moles.
Segmental arterial mediolysis
Old people Multiple abdominal saccular aneurysms Affects coronaries in young adults Dilatation, beading and dissections, results in intraperitoneal hemorrhage.
Biggest risk factor for endometrioma
Older than 45 y/o, bigger than 6-9cm endometrioma, look for an enhancing nodule in the endometrioma.
MQSA screen cleanliness
Once per week Darkroom quality of screen cleanliness= daily
Psoriatic arthritis
One of the distinguishing features besides the pencil in a cup deformity is the periosteal season (formation of new bone, particularly along the shaft of the bone)
As per NRC , Geiger muller should be calibrated every how often
One year
Radium-223
Only fda approved to treat prostate mets, alpha emitter. Less distance than other two alpha emitters, also only one proven to decrease mortality. This is primarily GI emitted, so common side effect is diarrhea. strontium 87 is another bone seeking agent used for mets, but its a beta emitter. Samarium is also another agent used, its a beta emitter with some gamma emissions, so its the only one that can also be used for imaging.
Gain in ultrasound
Only increases the returning echoes, so it only increases image brightness, not like power where it would influence penetrate bio effects and SNR.
What type of contrast can be used for myelograms
Only non-ionic low osmolality agents
Orbital pseudotumor and Tolosa-Hunt Syndrome
Orbital pseudotumor: idiopathic inflammation of extraocular muscles→ expanded muscle Unilateral, painful Most commonly lateral rectus Doesn't spare myotendinous insertions (versus Graves- painless, sparing insertions) Classically T2-dark, gets better with steroids Tolosa Hunt Syndrome: histologically identical to orbital pseudotumor, but involves cavernous sinus → and orbital apex, presents with multiple cranial nerve palsies Lymphocytic hypophysitis is similar , involves the pituitary usually third trimester or post partum, with thickening of the stalk.
Reverse halo sign
Organizing pneumonia, infarct, and paracoccidiomycosis
Gastric volvulus
Organoaxial, lesser curvature over the greater curvaature, happens in older ladies, Mesenteroaxial, antrum over the fundus, more likely to be ischemic, happens in kids.
Freiberg's
Osteochondroses (flattening sclerosis , indicative of ostenecrosis) 2nd metatarsal head
Osgood-Schlatter disease
Osteochondroses (flattening, sclerosis indicative of osteonecrosis) Tibial tubercle
Sever's
Osteochondroses (flattening, sclerosis, indicative of osteonecrosis) Calcaneous apophysis.
Panner's
Osteochondroses (flattening, sclerosis, indicative of osteonecrosis) Capitellum, no lose body, patients 5-10 y/o, usually younger than the osteochondral defects which can present with loose body if type 4 in progression) -associated in kids 30% with radial head subluxation, the OCD is likely due to faulty mechanics.
Sin den-Larsen-Johansson syndrome
Osteochondroses of the inferior patella, superior to Osgood Schlatter's disease, but same disease process (different location)
Kohler's disease
Osteochondroses(in epiphysis or apophysis , where you have flattening , sclerosis, etc indicative of ostenecrosis) . Tarsal navicular location
Coherent (Raleigh) scatter
Outer shell electron is hit by a photon, which then absorbs this energy via vibration, then the electron releases a photon of the same energy of the incident photon (exact same energy) without creating an ionization event. Primarily occurs at low energy states. incident photon has same energy, freq, and wavelength.
Most common cause for failed uterine artery embolization
Ovarian artery feeding fibroid
Granulosa cell tumor
Ovarian mass with internal vasculaity, since they make estrogen you will also see endometrial hyperplasia.
Peritoneal inclusion cyst
Ovary keeps making fluid, and adhesions from prior surgeries, endometriosis, etc, create bunch of fluid usually entrapping the ovary that conforms to the regions of the pelvis.
Macrodystrophia lipomatosa
Overgrowth of digits with associated bowing, and enlargement of soft tissues. usually the 2nd and 3rd digits, a form of localized gigantism, usually due to lipomatous replacement of the median plantar or the median hand nerves, with overgrowth then of the 2nd or 3rd digits.
Epiphyseal overgrowth
Overgrowth of the femur, Tibia and even patella for example, can be due to chronic synovitis, the hyperemia leads to increased bone growth.
PA sarcoma vs PE
PET/CT-> sarcoma would be greater than the blood pool
Acroosteolysis DDx
PINCH-FO P-psoriasis I-thermal injury N-neuropathy (diabetes or leprosy) C- Collagen vascular disease (Raynauds and scleroderma) H-hyperparathyroidism F-familial (Hadju-Cheney syndrome) 0-other (polyvinyl chloride)
Humingbird sign
PSP
PVNS vs synovial chondromatosis
PVNS usually doesn't calcify, usually in kids, polyarthropathy, same as peripheral nerve sheath tumor , blooms on gradient echo, associated with hemarthrosis. Tx synovectomy Primary synovial chondromatosis usually mono arthropathy (70% in the knee), metaplasia of synovial, get calcified round bodies , all same size). Usually 40-60 y/o, not kids.
Osteoid Osteoma
Painful sclerotic cortical lesion with lucent centered nidus. Occurs in patients younger than 30. Nidus is surgically removed or thermally ablated, first option after aspirin is RFA (these things are usually in posterior elements so before RFA make sure theres space from epidural space). May mimic osteomyelitis. Bone scan double-density sign versus photopenic area for osteomyelitis. >3cm called osteoblastoma
Enchondroma
Painless, no periosteal reaction, no endosteal scalloping, no defined sclerotic borders Ring and arcs (except in hands and toes), actually most common lyric lesion in hands and feet Differentiation btw enchondroma and low grade sarcoma is pain (enchondroma is painless)
AIDS cholangitis
Papillary stenosis with intrahepatic strictures is highly specific. Usually on recap want to see cbd dilatation of 8mm with distal tapering of the terminal 2-4mm of duct along with abnormal contrast retention.
Thyroid cancers
Papillary-most common, microcalcifications, nodes tend to be calcified too. Lymphangitic spread, can cause miliary pattern in lungs Follicular- second mose common, spreads hematogeneously Medullary- neuroendocrine, calcitonin , doesnt respond to I131, can be MIBG avid Anaplastic-old people, post radiation, bad one, lymph nodes and hematogenous, doesnt respond to I131 Hurthe cell- type of follicular, doesnt respond to I131, FDG PET is the way to go.
Types of thyroid cancer
Papillary= microcalcifications in glands and in the nodes, lymphatic mets, responds to I-131 Follicular= less benign than follicular, hematogenous mets, Hurthe variant responds less to I-131 so best way to assess is with PET scan Medullary= high calcitonin, neuroendocrine tumor, (MENIIA AND B), hematogeneous and lymphatic spread, doesn't respond to I-131 Anaplastic=old ladies, bad one, doesn't respond to I-131.
Types of collimators
Parallel hole= collimator and detectors as close as possible to the patient for the best spatial resolution (this is affected by distance). Sensitivity is NOT affected by distance. Pinhole= Magnifies and inverts the image. Sensitivity is garbage. Converging= magnified without inverting. Diverging= take a large object and makes it small.
Which subtype of osteosarcoma has the best prognosis
Parosteal
Parosteal vs periosteal osteosarcoma
Parosteal osteosarcoma tends to be in the metaphysis. It has a lot of calcification, doesn't involve the cortex (no cortical thinning), has a cleft connecting it to bone, tends to be metaphysis (likes posterior distal femur like cortical desmoid lesions). Periosteal osteosarcoma tends to be more lytic. It involves the cortex and causes cortical thinning, also tends to be in the diaphysis. Perisoteal in kids, paroesteal middle age/young adults. Parosteal osteosarcoma has best survival rate.
Right recurrent laryngeal nerve
Passes under the right subclavian artery , the left recurrent laryngeal nerve passes under the aortic arch, both come off the vagus at the common carotid artery regions and both course upward from through the esopahgotracheal region.
Most common site of metastasis of neuroblastoma
Past 12 months is bone, MIBG scan is more sensitive than bone scan. I123 MIBG will show uptake in liver, also in the heart (sometimes) and thyroid/salivary glands. No bone uptake.
Sarcoidosis on cardiac MRI
Patchy, nodular subepicardial enhancement
X ray beam quality
Penetrating ability of the x-ray beam How to improve beam quality: Higher x ray beam higher energy, increase x ray tube voltage, decrease voltage wavelength ripple, and increase x ray tube filtration; this will decrease contrast as the overall beam energy's increased (making it more difficult to differentiate tissue) but the beam can penetrate more decrease ripple decreases contrast bc beam quality increases (less able to tell tissues apart).
Meckel scan drugs
Pentragastrin-enhances uptake of pertechnetate by the gastric mucosa. H2 blockers (cimetidine and ranitidine) block secretion of pertechnetate out of gastric cells making it stick longer) Glucagon- slows gastric motility False negative: recent in Vito labeling of RBCs, recent barium (attenuated).
Thyroid acropachy features?
Periostitis of metacarpals and phalanges, more commonly radial aspect of 1-4th metacarpals, and also particularly ulnar aspect of fifth metacarpal. Occurs in hyperthyroid patients post-thyroidectomy.
Avulsion of the base of the fifth metatarsal
Peroneus brevis or also lateral aspect of the plantar aponeurosis.
Zipper artifact
Phase encoding direction, perpendicular to radiofrequency direction Stray RF pulses Caused by inadequate shielding Less commonly due to malfunctioning RF transmittor Fixed by: - closing door - remove electronic equipment (check for anesthesia stuff)
Indium 111-leukocyte scan
Physiologic activity in the lung until 6 hrs, anything passed that is abnormal , and blood activity passed 18 hrs is abnormal. Why indium-111 is usually done around 24 hrs after administration.
Physiologic growth
Physiologic periostitis of the newborn, actually happens after 3 months. Proximal femoral involvement first , then tibia, always hits the diaphysis. Not physiologic periostitis if befor 1 month, tibia before femur, or it doesn't involve the diaphysis.
Factors affecting spatial resolution in DR
Pixel detector in DR is built into the DR flat panel Direct systems that avoid lateral dispersion of light have betters spatial resolution Limited by the DEL (detector element), smaller detector element= better.
Tech 99 MAA to assess shunts
Place uptake marker in liver and in the lungs, then counts will tell you if you have shunt, anything more than 10% means you have to decrease Ytrium or other chemo embolization a gent prior to administering. If 10-15% shunt decrease ytrium by 20%. More than 20% shunt, contrinadicated to use chemoembolization.Ytrium is a beta emmiter, half life 64 hours, so after 4 half lives you should have done well (around 11 days). Ytrium contraindicated if MAA shunt >20% dont wanna give more than 30Gy to the lungs, before you give Ytrium you gotta embolize the right gastric (prevent nonhealing ulceration in stomach) and GDA.
Energy of a photon
Plancks constant x (speed/wavelength) or Planck's constant x frequency
Most common parotid tumors
Pleomorphic adenoma (80%), 2nd is warthins (unilateral too), both FDG avid. Majority of pet positive single parotid lesions ARE THESE TWO.
Endometrial thickeness
Post menopause>5mm biopsy Hormone replacement 8-11mm is cutoff
Pellegrini-Stieda lesion
Post traumatic calcification medial to the medial femoral condyle. May be secondary to MCL avulsion injury.
Pellegrini-stieda lesion
Post traumatic calcification medial to the medial femoral condyle. May be secondary to MCL avulsion injury. It's essentially calcification of the medial collateral ligament border, or tibiocollateral ligament.
Urachal remnants
Predisposed to adenocarcinoma , midline superior bladder mass.
Main branch IPMN
Premalignant , needs to come out If duct is >10mm (some sources >15mm) then it needs to come out Enhancing nodule is malignancy
Lobular carcinoma in situ of breast
Premalignant , up to 25% is upstaged so there should always be excisional biopsy after stereotactic or ultrasound guided biopsies come back with this result.
Receiver Bandwidth Formula
Primary determinant of noise in MRI If you increase the receiver bandwidth formula, then you have more noise coming in Also the size of the coil, the greater the coil size, the more protons contributing to image size. The use of local or focal coils reduces noise
Lower lobe predominant
Primary diskinesia, hematogenous mets, rheumatoid , asbestosis, UIP.
Nephroblastomatosis
Primitive metanephric blastema thought to be precursor of Wilms tumor. Commonly seen in neonate kidneys. Normally regress by 4 months of age. Bilateral lobulated and enlarged kidneys. Marked compression and stretching of pelvicaliceal structures. Large echogenic and lobular kidneys. May demonstrate diffuse hypoechoic cortical thickening. Nephrogenic rests are generally cortical, hypoechoic, low attenuationand T1 hypointense. Followed up bc they can turn into Wilm's.
Nephroblastomatosis
Primitive metanephric blastema, precursor to Wilms. Hypodense renal rind is noted.
Greatest risk of infection post TACE
Prior Bilioenteric procedures, as the biliary system is then colonized by colonic bacteria/flora.
Least likely agent to cause NSF
ProHance( gadoteridol)
Brehmstralung radiation
Produced when a traveling electron interacts with the nucleus of an atom, changing the path of the electron releasing energy as a result. Produces spectrum of electron energies and increases with increasing atomic number.
Fission
Produces particles with neutron excess. Xe-133; I-131; Mo-99 , and they are beta minus emitters. Neutron deficit is from cyclotron and they are F-18; C-11;N-13; O-15. They have positron emission. Others; ga-67; co-57; In -111; I-123 have neutron deficit but do it via electron capture.
She in mri
Proportional= voxel x (nex - number of excitations)/ (receiver bandwidth) Increasing matrix size decreases voxels, decreasing fov decreases voxels. Voxel or pixel size = FOV/matrix Reducing the slice thickness also decreases the pixel size.
Midline prostatic cysts
Prostatic utricle (associated mostly with hypospadia, midline , off the prostatic urethra, also renal agenesis, prune belly) Seminal vehicle cysts (lateral to the prostate, associated with polycystic kidney disease, renal agenesis) Mullerian (paramesonephric) duct cyst , midline like the prostatic utricle cyst, but usually above the prostate in location, above the prostatic base. No association with bad shit like the prostatic utricle cyst. Usually tear dropped shape. Does not communicate with the prostatic urethra. Cowper (bulbourethral) cyst= two bulbourethral gland that drain into the bulbous urethra, can get clogged and lead to large cystic structures. Should be below prostate.
MRI sequences
Proton density : TR >2000. TE 20-30 T1 : TR<500. TE <20 T2: Tr>2000. TE>70
Killian-Jamieson diverticulum
Protrudes through a muscular gap in the anterolateral wall of the cervical esophagus inferior to the cricopharyngeus and lateral to the longitudinal muscle of the esophagus just below its insertion on the posterior lamina of the cricoid cartilage which is referred to as the Killian-Jamieson space. Less common and considerably smaller than Zenker's. Appear as persistent left-sided (75%) or bilateral (25%) outpouchings from the proximal cervical esophagus below the cricopharyngeus Much less likely to cause symptoms or to be associated with GERD than Zenker's. .
Ideal swan ganz placement
Prox pulmonary arteries, within 2 cm of hilum.
I-131Mibg
Pt should take lugols solution pretreatment
Contraindications to pulmonary angiography
Pulmonary HTN (right heart pressure > 70/20) and LBBB (bc if you then make a RBBB you can stop the heart) If in an emergency, and it must be done, then inject the right or left pulmonary vein, not the main, and use a low osmosis agent.
Carneys triad
Pulmonary chondroma, extra adrenal paragangliomas and GIST tumors.
Cor triatriatum sinistrum
Pulmonary vein draining into the left atrium that has an unneeded fibromuscular septum Can cause pulmonary artery hypertension from pulmonary venous stenosis, the septum creates the appearance of 3 atria
What determines frame rate
Pulse repetition frequency (PRF) # scan lines Increasing PRF increases frame rate but decreases axial FOV.
Pulsed Doppler and power within patient
Pulsed Doppler deposits the most power within a patient, as compared to b and m mode.
Pyonephrosis
Pus accumulation in the pelvis of the kidney, if it leads to dilatation of collecting system definite treatment is percutaneous nephrostomy to relieve.
Emphysematous pyelitis vs emphysematous pyelonephritis
Pyelitis is gas in the renal collecting system, treated with antibiotic (IV) Pyelonephritis is in the renal cortex and is to with surgery and debridement.
Linearity in dose calibrators measured how often
Quarterly
MQSA for mammography to do repeat analysis
Quarterly
Caplans Syndrome
RA + upper lobe nodules and pleural effusion. Normally RA has centrilobular nodules in the lower lobes or looks like COP /UIP.
felty syndrome
RA>10 yrs +splenomegaly + neutropenia
RB-ILD and DIP
RB-ILD-apical centrilobular GG nodules + smoking history DIP- end spectrum of RB-ILD, peripheral lower lobe predominant GG , with small cystic spaces. If a pt has centrilobular upper lobe predominant nodules (GG) and is a smoker-RB-ILD, if not a smoker think hypersensitivity pneumonitis (look for air trapping/mosaic attenuation).
MUGA
RBC tagged angiogram Requires gating False low EF= LAO screwed up, can cause overlap of LV and LA or RV FALSE HIGH ef- WRONG BACKGROUND ROI , OVER THE SPLEEN, CAUSE OVER SUBTRACTION OF BACKGROUND AND ELEVATE EF.
PET situations
RCC cold, oncocytome hot Cold ground glass pulmonary nodule-cancer, hot gg nodule-infection Metformin drives uptake throughout bowel, favors colon Lymphoma normally hot, except MALT. Testicular cancers: Seminole is hot, nonseminoma are cold. Osteosarcoma and pet: Higher suv higher tumor grade, baseline suv independent and significant predictor of overall survival (more=bad). Can be used to evaluate the effectiveness of neoadjuvant chemotherapy.
Omental infarct vs epiploic appendagitis
ROI-omental infaects are on the right, RightOmentalInfarct, these also tend to be bigger Epiploip appendagitis tends to involve the left side, and are smaller.
Retroperitoneal fibrosis vs lymphoma
RPF is more common in men (3:1, ages 40-60) and tends to spare the posterior aorta. Ig4 related disease.
Radial vs ulnar artery
Radial artery is skinnier, ulnar artery usually gives off the common interosseous, and the ulnar artery terminates at superficial palmar arch .
To prevent cardiac MRI ghosting /motion
Radial k space-instead of rectangular k space this spreads the motion in a radial direction, spreads the ghosting. Can also do cardiac or respiratory gating. Prevent pulsatile flow- gradient moment bulking, application of phase shift to prevent moments there. Saturation pulse-gradient parallel or perpendicular to the image plane to prevent ghosting of the imaged structures.
Y-90
Radioembolization Pure beta emitter, half life is 2.7days, 175 and 185KEV Before administration do 99mTc MAA hepatic arterial injection, lung shunt , has to be less than 10, more than 20% can get radiation pneumonitis. Delivers 100-1000Gy to area.
Standard focal spot size
Radiography =1.2mm CT =1.0mm Fluoroscopy= 0.3-1.2mm Mammography = 0.3mm Mammography (magnification)= 0.1mm
Latitude
Range of a film to make a decent interpretation , narrower latitude in mammo compared to plain film.
Spigelian hernia
Rare hernia occurring between the transverse abdominis and rectus muscles Associated 75% time with crytoorchidism among male infants.
Phylloides tumor
Rare rapidly growing tumor, large when first detected, surgical removal is next step when path comes back.
Urethral cancer in males
Rare, but most commonly is squamous cell with the exception of, Prostatic urethra most common is transitional cell (closest to the bladder) If there's a diverticulum (like urachal diverticulum) you get adenocarcinoma.
Calcinosis cirscumcripta
Really dense soft tissue clarifications, associated with dermatomyositis , polymyositis, and lupus.
Best view to see esophageal diverticulum
Recumbent (so there's no dilatation of the esophagus) and to increase venous return.
What determines whether a Giant Cell Tumor is malignant or not
Recurrence rate giant cell tumor has 4 characersitics: epiphyseal lesion eccentric epiphyses have closed nonsclerotic expansile borders
Tube current modulation can do what?
Reduce the dose without adversely affecting the image quality. It changes the dose along the z axis, where you get more dose in the skull bc bones thicker than in the chest bc lungs would allow more photons to pass.
Backing material in an ultrasound probe
Reduced pulse length but improves bandwidth, it prevents the crystals from vibrating , smaller pulse length means greater axial resolution. Reduced pulse length improves axial resolution. Kinda like putting your hand on a bell to keep it from vibrating. factors that improve axial resolution: shorter spatial pulse length higher freq transducer greater dampenin of transducer element (reduces pulse duration) broader bandwidth pulse(indirectly increases axial resolution by increasing damping (makes SPL smaller)).
Parallel imaging in mri
Reduces scan time by decreasing the phase encoding steps, using geometry of phased array coils. Missing k space is filled in with interpolated data.
Reducing frame rate in fluorsocopy
Reducing it from 30 frames/sec to 15 frames/sec leads to 25% drop in dose, bc you still gotta maintain mA to Drecrease excessive noise, blunting the dose reduction effect.
Sampling frequency and nyqist frequency (limiting spatial resolution)
Related , if you decrease one by half, the other decreases by half as well.
Tumoral calcinosis
Related to an inheritance familial disease where you have issues with phosphorous metabolism, and that leads to lobulations densities within periarticular areas, most commonly at the hips with intervening septa , there's no adjacent osseous erosions.
Relative biological effectiveness (RBE)
Relative capability of radiation with differential LETs to produce a particular biological reaction. RBE= dose of 250kv x rays/dose in Gy of test radiation Example: a reaction is produced by 5 Gy of test radiation. It takes 10 Gy of 250 kVP-xrays to produce the same reaction. What's RBE? 10/5=2, test radiation is 2 times as effective in producing this biological reaction that the standard 250kVP xrays. As LET increases, RBE will increase...to a certain point. Above 100keV/micrometer of tissue, RBE decreases with increasing LET bc the maximum potential damage has already been done.
Dexa scan
Relies on transmission measurements made at two different photon energies. Soft tissue will allow both to pass, bone will attenuate Low energy, how you can tell the difference.
Cortical nephrocalcinosis
Renal cortical necrosis (2/2 hypotension, common), chronic glomerulonephrosis, chronic Pyelo, Alport's syndrome.
Transplant vascular complications
Renal vein thrombosis within first week Renal artery thrombosis within first months Renal artery stenosis within the first years
Lung transplant complications
Reperfusion injury 4-7 days laters, non cardiogenic edema, pleural effusion acute rejection 8 days to 2 months, GG and intralobular septal thickening (no GG=no rejection). Improves with steroids. Bronchial anastomotic complications- leaks in first month, stenosis month 2-4 CMV-after one month, GG Chronic rejection- > 4months, peribronchial wall thickening, bronchiectasis, bornchilitis obliterans, air trapping COP= chronic rejection PTLD- within first year
Most common abdominal vascular variant
Replaced right hepatic (origin from the SMA) Most common biliaryh variant: right posterior segmental branch emptying into the left hepatic duct.
Hepatic artery variants
Replaced=different origin Accessory-duplicated vein If you see vessel in ligamentum venosum region its likely a replaced left hepatic via the left gastric The proper right hepatic is anterior to the right portal vein The replaced right hepatic is posterior to the right portal vein
CCAM
Replacement of normal lung parenchyma by abnormal tissue, which often includes visible cysts. Doesn't have predilections (like sequestration which is lower 2/3 lung on left usually)
Pulmonary AVM
Represent right to left shunt and can present with paradoxical embolisms. Single artery to single vein and are most common in the lower lobes. Osler Weber Rendu Treat if artery is more than 3mm (!!!) Coils-wanna eradicate it Also Glenn/Fontan procedures increase pressures and can lead to AVMs
Most common complications post whipples
Resection os pancreatic head, duodenum, gastric antrum, and always gallbladder. Jejunal loop is brought to right upper abd for gastrojejunal , choledojejunal ,or hepaticojejunal and pancreaticojejunal anastomosis. Complications: >1 day delayed gastric emptying, preserved NG tgube Amylase >50 for longer than 7-10 days (fistula).
Electron capture
Results in loss of a proton and gain of a neutron, the nucleus attracts a k shell electron and draws it in. GIIT -gallium -indium- -Iodine 123 -thallium
Peritoneal carcinomatosis
Retrovesical space is the most common spot due to natural flow of implants.
LEFT BUNDLE BRANCH BLOCK ON CARDIAC NUCS
Reversible or fixed septal defect, sparing the apex. Seen more in exercise and dobutamine tests.
Most common cause of fetal hydrops
Rh decensitazion
Double IVC
Right IVC drains into the right atrium. Left sided IVC drains into the left renal vein.
Most common abnormality associated with truncus arteriosum
Right aortic arch
Aortic anomalies and associated findings
Right aortic arch with aberrant left subclavian is usually incidental not assoc with anything, same for double aortic arch Right aortic arch with mirror imaging and circumflex aortic arch are assoc. with cardiac anomalies
Most common coronary anomaly in TOF
Right coronary off the LAD.
Heterotaxy syndrome
Right sided heterotaxy=two minor fissures, livers on the right , absent spleen, reverse IVC/aorta (IVC to the left), more cardiac anomalies Left sided heterotaxy= no minor fissures, polysplenia, azygous continuation of the IVC. Associated with biliary atresias. Less cardiac anomalies.
Tumefactive nerosis
Ring enhancement, part of it may be open. On t2 may show surrounding thin low t2 ring, typical for this. It wont restrict diffuse, unlike abcsess or neoplasm.
Single segment ct scanner
Rotational speed/2=temporal resolution, temporal resolution in MRI is TRx views per segment .
Only PET agent made in a generaotr
Rubidium
Evaluate patent AVF for dialysis
Rule of 6s >600ml/min flow >6mm diameter <6mm from skin (for easy access )
Middle cardiac vein
Runs with the PDA in the interventricular groove.
MRI heat laws for patients
SAR= specific absorption rate SAR=Bo^2 x Alpha ^2 x Duty cylce Based on magnet strength, flip angle and TR time Double magnet it quadruples (Bo) Increase flip angle (Spin echo uses 90 and 180 vs GRE which uses less than 90 degree RF pulses, so spin increases SAR more than GRE). This is Alpha . Longer TR, more time to cool down, half TR increase temperature. TR is inverse of duty cycle, increasing TR decreases your duty cycle. FDA no temp increase above 1 Celsius in the patient FDA limits are 4w/kg over 15 mins and 3 w/kg over 10 minutes.
Wolfian ducts
SEV (boy name) seminiferous tubules, ejaculatory ducts, vas deferens Prostate and lower 1/3 of vagina is made by urogenital sinus
scanning field of view and gantry bore
SFOV is 70% of gantry bore
Marginal artery of Drummond
SMA to IMA connection, anastomosis of terminal branches of the SMA to the left colic and sigmoid branches of the IMA forming a continuous circle or arcade along the inner border of the colon.
Artery of Riolan
SMA to IMA, middle colic connected to the left colic, which then goes to IMA. IMA to internal iliac art collateral: superior rectal (off IMA)-> inferior rectal->internal pudendal->ant branch of internal iliac art.
SNR in MRI
SNR= voxel volume x square root (Nx x Ny x NEX/BW (bandwidth)) Nx and Ny are the number of frequency and phase encoding steps, BW is receiver bandwidth
Best for sampling extratemporal interictal areas
SPECT is the most sensitive during ictal periods. PET is most sensitive feuding ictal periods in temporal lobes seizures.
SPECT vs PET
SPECT uses the same crystal as planar, NaI. PET since it detects 511kEv uses BGO, GSO, LSO. Thicker crystals have worse spatial resolution and more Compton scatter, however with them being higher density (LSO being the densest), you have potential to reduce thickness of crystal and improve resolution. LSO is best compared to BGO (original) and GSO.
Axial resolution in ultrasound
SPL determines it, which is the length of an entire pulse, equivalent to approx 2 x the wavelength. Also transducer frequency. Axial resolution = 1/2 SPL approximately Transducer frequency determine axial resolution? Yes, Increased TF leads to decreased SPL (less wavelength), and hence better axial resolution. Why you use higher frequency in mammo (less SPL bc less wavelength) compared to an abdominal probe. Axial resolution is not depth dependent The PRP determines the axial field of view.
spatial pulse length is determined by
SPL= n x wavelength (Wavelength = c/f) and n is the number of wavelengths per pulse If you decrease the wavelength, aka increase the frequency then you increase axial resolution because axial resolution is = SPL/2 Greater frequency greater axial resolution, but less penetration. Greater frequency means lesser spatial pulse length. PRF is the number of pulses per second PRP (pulse repetition period) = 1/PRF
Low lung volumes in neonates
SSD—> bilateral granular opacities, no pleural effusions, increased risk of pulmonary hemorrhage and PDA Group B strep—> similar appearance, usually with pleural effusion too.
Glenn procedure
SVC to the pulmonary artery , used to tx atrial atresia and hypoplastic left heart -predisposes patients to increased risk of AVMs
Cryoablation
Same as RFA, tumor should shrink overtime, especially by 6 month post scan Good result is lower density relative to the adjacent kidney. More than 10 HU increase post contrast is considered enhancement. Should be low on T2 and low/iso on T1. risk of bleeding with cryo is higher than with RFA, bc you arent ablating a small vessel.
Factors that affect contrast resolution in CT
Same as SNR MA, KVP, slice thickness (thicker the better), matrix size, FOV, reconstruction filter
aliasing in ultrasound
Sampling too low of a pulse repetition frequency
Upper lobe predominant
Sarcoidosis, RB-ILD, lung cancer, silicosis /coal workers, ankylosis spondylitis.
PET scatter
Scatter coincidence: one fo the photons has a Compton interaction and is deflected, but still hits detector within allotted time. Compton event lowers the photon energy, therefore you can reduce this by using a more narrow photo-peak window. Random coincidence: two photons, from different annihilation reactions just so happen to land within the same coincident window. This increases with dose, fix by decreasing dose/counts and a narrower time window setting. LSO has fastest decay time (bounce back faster to receive next signal). Crystal thickness is the primary limiting factor of spatial resolution in PET.
Schizencephaly: associations and mimic
Schizencephaly: grey-matter lined cleft that will extend through entire hemisphere Associations: Optic nerve hypoplasia (30%) Absent septum pellucidum (70%) Epilepsy (50-80%) Septa-orbit dysplasia Grey matter Heterotopia Unlike porencephalic cyst, open-lip schizencephaly is lined by gray matter.
Most common mediastinal neurogenic tumor
Schwanoma
Cortical desmoid
Scooped out appearance at posterior medial epicondyle of distal femur. DONT TOUCH LESION . At the insertion of the adductor magnus apponeurosis, or the origin of the medial head of the grastrocnemius. Low T1 high t2 saucer shaped lesion. Usually kids 15-20 y.o.
spatial resolution
Screen film mammogram : 15lp/min Digital mammogram : 7lp/min Digital radiography: 3lp/min CT: 0.7 lp/min MRI: 0.3 lp/min
Film radiography and screens
Screens allow photons to be converted to light, thicker screens hold more light, and allow for shorter exposure times, aka less patient motion. The thicker the screen the more the diffusion of light though, and worse the spatial resolution. thicker screens will allow more photons, but the overall effect on quantum motle is net neutral bc exposure time is decreased by automatic exposure control.
Multiple atresias
Secondary to vascular insult, I.e. jejunal atresia is secondary to a vascular insult.
Microvascular obstruction on cardiac mri
Seen best at 25 sec post gad imaging (first pass post gad imaging) islands of microvascular obliteration with lack of enhacement, as a result of acute MI. Not seen in chronic states due to eventual development of scarring.
Coned cecum
Seen in entomaeba histolytica and yersinia . The ileum is spared in entomaeba histolytica. Colonic TB also gives you coned cecum, but it invovles the TI as well.
Mesocardial enhancement
Seen in hypertrophied cardiomyopathy (usually septum) , myocarditis, pulm htn, and dilated cardiomyopathy Amyloidosis is diffuse subendocardial delayed enhancement not following a vascular distribution
Cortical desmoid
Seen in the posteromedial aspect of the posterior medial femoral condyle metaphysis. Seen in kids 10-15 years old. Intra-cortical/medullary lesion, with homogeneous enhancement. Due to stress from attachment of medial head of the gastrocnemius and the adductor muscle.
Uterine blush
Seen on tc-99 pertecnetate scans and also bone scans, which is early uptake in uretus , that goes away over times , seen in every phase of the cycle in women.
Compression quality control and screen film contact quality control, how often per MQSA
Semi-annually , both
Ischeal tuberosity origin muscles
Semimembranosus and semitendinosus
Left minor fissure
Separates the anterior segment of the left upper lobe from the lingula
Lemierre's syndrome
Septic thrombophlebitis of the internal jugular from pharyngitis Complication is embolism of the pulmonary artery
Seotocallosal vs callosimarginal
Septocallosal is more inferior and medial.
Osteomyelitis
Sequestrum is the dead bone, surrounded by the involucrum, and there's a tract from the medullary cavity to the Osteum/periosteum which will drain to the outside soft tissues leading to an abscess formation called the cloaca.
Brodies abscess
Sequestrum-piece of dead bone inside bone Involucrum- periosteal reaction surrounding the dead bone Cloaca-track to the sequestrum
Types of ovarian cancers
Serous=most common, can be bilateral, papillary nodule with flow, tends to be unilocular Mucinous=third most common, can be bilateral , less papillary nodules, more septations Enodometroid ovarian cancer= endometrial cancer with mets to ovaries, also like granulosa theca cell tumor presents with thickened endometrium( which leads to increase estrogen so endometrium is thickened)
Filters and spatial resolution
Sharp filter= better spatial resolution (trade off is more noise) decreased SNR<--for bone Smooth filter= crappy spatial resolution (trade off is less noise) increased SNR<--for soft tissues
Shin splints vs tibial stress fractures on bone scan
Shin splint —>nml angio, and blood pool, increased delayed uptake. (Seen at the posteromedial prox 1/3 tibia due to attachment of soleus and tibialis muscles). Tibial stress fracture—> increased angio, blood pool, and delayed uptake
Epinephrine dose
Shock, give 0.1mg of 1:10000 IV Laryngeal swelling , 0.3mg of 1:1000 IM Cardiac failure 1mg of 1:1000 IM
T1 and T2
Short TR, TE will result in T1 weighting, by maximizing the longitudinal relaxation differences between tissues and mini Ming the transverse relaxation differences. Long TR, TE will result in T2 weighting - by maximizing the transverse relaxation differences btw tissues and minimizing the longitudinal differences. Proton density uses a long TR, and short TE, to minimize longitudinal and transverse differences, so it depends on nearby interactions.
T1* weighted gradient echo
Short echo times (<20msec) and small flip angles. Short echo times (T2) minime T2* contrast because when the TE is short, there is insufficient time for spin spin relaxation to occur, and so all substances, regardless of their T2 times, will appear similar.large flip angles promot T1 weighting by converting a large fraction f the longitudinal mag intotransverse mag, which allows differences to become evident during spin-lattice relaxation. Small flip angles allow substances with diff T1 times to remain clustered in signal intensity.
Tc99 chemical purity
Should be below 10micromilligrams/AL3+; if not the Al3+ will accumulate in the liver.
Differential function of kidneys
Should be between 45-55% , taken during the cortical phase the cortical phase for DTPA and MAG3 starts at 1 min and ends at 4mins.Best agent to determine split function is not DPTA or MAG3, its DMSA (cortical binding agent used mainly for kids).
Nuclear medicine materials held for self decay storage
Should be held for 7-10 half lives, so in the case of a Tc99 sulfur colloid scan, to discard the Tc needle you need to wait (6 hr half life x 10= 60 hrs more or less).
Post radiation breast changes
Should be seen by 6 months, up to 12 months with trabecular and skin thickening. If more than 12 months then suspicious for recurrence. Presence of scar enhancement at the post lumpectomy bed is up to 18 months normally.
Liver biopsies
Should include passing through 1cm of liver parenchyma before lesions to ensure tamponade of tract in case there's a bleed.
Leakage radiation
Should not exceed 1mGy at 1 m from source
Tc99MAA
Shunt (ASD, vsd) Typically 10-100 micrometers, capillary is 10 micrometers Reduce number of MAA particles if kid, pulm htn, one lung, or pregnant. (Still get same dose of tc) Clumped MAA (blood into the syringe) See persistent cue on (biological half life 30 secs, )likely secondary to air trapping (COPD). Accumulation of tracer over RUQ: fatty infiltration of the liver (xenon is fat soluble). If you use Tc99 DTPA aerosol: slow wash out, multiple projections (xenon is one-two pojkections), clumping is common in the mouth, central airways and stomach (from swallowing).
SNR
Signal changes directly with increased x ray flux. Twice the X-ray twice the signal. Noise changes by a factor of square root of N. Twice the xrays, square root (2) or 1.4. Factors that increase SNR: Higher mA Longer rotation time Higher kvp Larger slice thickeness Large pixel (fov/matrix) Decreased pitch
Left heterotaxy
Single fissure bilaterally Polysplenia Azygous continuation of the ivc
LIP
Sjorgens and kids with HIV
Solitary fibrous tumor of the pleura
Slow growing tumor of the pleura so can grow large, no calcifications, no pleural effusions, no rib destruction. known as benign mesothelioma, associated with hypoglycemia and osteodystrophy.
Celiac sprue
Small bowel malabsorption of gluten Assoc with pulmonary hemosiderosis (Lane Hamilton syndrome) Increaed risk of bowel wall lymphoma Dermatitis herpetiformis CT—> bowel fold reversal (Ileum having more folds than jejunum), Moulage sign (dilated bowel with effaced folds-tube with wax poured in it) Cavitary lymph nodes (low density), splenic atrophy
Septooptic Dysplasia
Small optic nerves and failure to develop septum pellucidum, also pituitary issues, midline defect crap
Spatial resolution in fluoro
Smaller FOV better resolution Image receptor limitations, detector element for FPD, and television for I.I. Frame averaging increases SNR (less mottle), and more susceptible to blur Pixel binning increases pixel size, reduces spatial resolution, but improves SNR (just like in MRI).
Higher kVP
Smaller attenuation coefficients, less contrast
Factors that affect spatial resolution in CT
Smaller focal spot size Less magnification, less blur Reduce detector size in cc dimension (z-axis), the thinner the detector element aperture, the better the spatial resolution in the z-direction. More projections, more data Decreased FOV, increased matrix—> to decrease pixel size (less pixel size easier to determine two points as separate if they are close together) Focal spot- smaller better: determines spatial resolution in the x-y plane...side to side. Detector size -smalle better: determines spatial resolution in the z plane...CC.
Mammo uses
Smaller focal spots, lower mA(smaller focal spot would burn target faster), longer exposure time (to prevent heating of target anode) Regular radiology uses glass as the tube cover Mammo uses beryllium bc less attenuating (taking into account less energetic x-rays)
Factors affecting spatial resolution in CR
Smaller laser spot size *red light* better Thicker phosphor plate more light spreading worse spatial resolution Sampling frequency (rate of light sampling) results in smaller pixel pitch (distance btw adjacent pixels) leads to improved spatial resolution Smallest imaging plate for area of interest, for fixed matrix size CR systems, using smaller plate for given field of view improves spatial resolution.
Mesoblastic nephroma
Solid renal tumor, less than 1 yo, often involves the renal sinuses. If more than 1 y/o, suspect Wilms.
Ameloblastoma (adamantimomoma of the jaw)
Solid tumor, multiseptated, expansion of the mandible. most aggressive looking one .
Fibrous tumor fo the pleura
Solitary tumos, arising from visceral pleura. Not associated with asbestos. No cals, rib destruction or pleural effusions hypoglycemis (make IGF-2) Hypertrophic osteoarthropathy (make hyaluronic acid)
Spatial resolution in MRI
Spatial resolution is equivalent to voxel , voxel=slice thickness x FOV/matrix Smaller voxel = better spatial resolution Gradient also affects spatial resolution, gradient with higher amplitude (more intense) or one applies for a longer period of time results in better spatial resolution. Makes sense since the point of a gradient is to localize stuff. Slice thickness: for thicker slice you can either increase the transmit RF pulse bandwidth (the slice selection pulse), or you can decrease slice selection gradient. For thinner do the opposite. The thinner the slice the better the spatial resolution (increase selection gradient and decrease pulse bandwidth).
Full width half maximum
Spatial resolution= 1/(2 x FWHM)
Ultrasound encounters focal fat, what artifact
Speed displacement artifact, the machine is set to encounter tissue at 1540m/sec, and fat slow down signal so it takes longer fo the signal to return, so the machine thinks the object is further away.
Ultrasound speed of sound
Speed of sound= Transducer freq x wavelength ; 1540m/s is the speed of sound If you increase transducer frequency you decrease the penetration depth.
spin echo vs gradient echo
Spin echo images are used for cardiac anatomy. Gradient echos (blood is bright) are used for cardiac function.
Staging of lung cancer for Non-SCLC?
Stage 1: Tumor surrounded by lung or pleura --> SURGICAL RESECTION Stage 2: Locally advanced disease without mediastinal involvement --> SURGICAL RESECTION Stage 3: Mediastinal involvement --> SURGICAL + ADJUVANT CHEMOTHERAPY/RADIATION Stage 4: Metastatic - CHEMOTHERAPY T1A:<2cm T1B:2-3cm T2A: 3-5cm, >2cm from carina T2B: 5-7cm, >2 cm from carina T3: >7cm, <2cm from carina Any involvement of non vital structures, like the chest wall, mediastinal pleura is automatically T3. Any involvement of vital structures, like mediastinal fat, trachea, heart, esophagus is T4.
Prostate cancer staging
Stage 2 is within capsule Stage 3 is outside the capsule (gotta be the answer) Stage 4 is obturator lymph nodes
cervical cancer
Stage 2b is parametrial invasion , if it spreads beyond the T2 dark rim surrounding the cervix, the parametrium contains uterine vessels, hence the need to know bc then its easier to spread. Stage 2b needs chemo/radiation before surgery. Involvement of the lower 1/3 of the vagina also gets parametrial invasion.
Staging of lung cancer
Stage 3b is unresectable, implies N3 or T4disease T3=two masses in the same lobe, T4= two masses in different same side lobes Supraclavicular, scalene, contralateral mediastinal or hilar adenopathy; tumor in same lung but diff lobes from primary mass, malignant pleural effusion. pleural effusion- considered M1a (same as tumor in contralateral lung)
Lung cancer follow up
Stage IB and II or above need brain MRI
Prostate cancer
Stage II abuts the capsule Stage IIIa extension through the capsule (T3a), bulging of the capsule, invovlmenet of the seminal vesicles and nerve bundle.
Neuroblastoma
Stages: 1= confined to organ of origin 2=outside organ of origin but not on contralateral side 3=contralateral side 4=distant Mets 4s= Mets to liver and skin are considered as good prognostically as stage 1. Has to be younger than 1 year old, same side of body Mets, and involvement of the skin or liver.
FDA mandated maximum pt skin entrace exposure rate
Standard - 88 mGy/min (10R/min), High output - 176mGy/min (20R/min)
Inversion revocery
Start with 180 degree than wait for fat (120-160msec) to saturate, then hit the 90 RF to not show anything with fat, or wait for water (200msec) then hit the RF90 , and you null water. STIR is much less susceptible to magnetic susceptibility (metal) and field inhomogeneity. STIR cannot be used with Gd+ bc fat and Gad both get sated out being short and similar T1 shorterners, both get nulled out. Time to inversion creates a longer study, increases TR.
Types of fixes for dissections
Static- dissection flap in the feeding artery (tx with stenting) Dynamic- flap dangling infront of ostium ( tx with fenestration)
Symptomatic postmenopausal woman on tamoxifen
Still sue <5mm criteria for biopsy.
Malignant calcifications in lungs
Stippled and eccentric nodule Lamellated (ring like), central, popcorn, and diffuse are benign calcifications
Most common GI site for sarcoid
Stomach, can give you the ram horn deformity on barium study, likely secondary to narrowing of the antrum (can be seen with TB, Crohns, sarcoid, scarring 2/2 peptic ulcer)
Normal distribution of free Tc pertechnetate
Stomach/gi, salivary gland, kidneys/bladder thyroid and choroid plexus (but not cerebral cortices, if you see cortices than its a right to left shunt)
Breast feeding and nuc med
Stop breast feeding for 1 day after Tc Stop breast feeding for 1-4 weeks post In-111, Ga67, and Tl-201 (longer half lives) Stop breast feeling 2 weeks prior to G-67 and I-131 to prevent radiation to the breast. Post I131- Stop till next pregnancy Post I123-resume after 48 hrs Post Tc-99m pertechnetate- resume after 24 hrs
Types of urethral strictures
Straddle injury,hits the proximal urethra, can affect the membranous and the bulbar urethras (since it hits the proximal urethra) and can therefore hit the UG diaphragm, so you get contrast from the RUG in the perineum(anterior urethra) and the extraperitoneal space(posterior urethra injury). Gonococcal usually leads to a long stricture involving the distal bulbous urethra , saddle injury is a short segment.
Paget-Schroetter syndrome
Stress/effort thrombosis Involves artery or subclavian vein Venous component of TOS Usually young males, overhead motions. Tx= thrombolysis+ balloon angioplasty. Stent would break if first rib or cervical rib keeps hitting it.
Gibbs artifact
Stripe sign
Bone met nuclear medicine treatment
Strontium-B emmiter, most bone marrow toxicity, renal excretion Samarium-B emmiter and some gamma , less bone marrow toxicity, renal excretion Radium-alpha emmitter but short distance, least bone marrow toxicity, GI excretion, improves survival (prostate mets)
Age of blood on mri
Subacute (<24 hrs), acute (1-3 days), early subacute (3-7 days), late subacute (1-2 weeks), chronic (>2 weeks)
Femoral fractures with greatest risk of avascular necrosis
Subcapital and femoral neck fx (bc they are intracapsular)
Amyloidosis
Subendocardial enhancement in a non vascular distribution
Fibrouds
Submucosal is a myomatetral fibroid with extension into the submucosal region Serosal fibroid is a myometrial fibroid with extension into the serosa.
Fissures of the lung
Superior accessory fissure=separates the superior basal segment from the rest of the basal segments. Inferior accessory fissure= separates the medial basal segment from the rest of the basal segments.
Harlequin eye
Superior and lateral orbital wall elevation from unilateral early fusion of coronal suture, aka from unilateral brachycephaly called plagiocephaly. its due to elevation of the lesser wing of the sphenoid bone.
rectal arteries
Superior from ima Middle from internal iliac Inferior from pudendal(which comes in off internal iliac)
What makes the aortic nipple
Superior inter coastal vein, parallels the aortic arch, drains into the SVC, drains the second through fourth intercoastal spaces.
Cavernous sinus drainage
Superior petrosal and inferior petrosal (superior to transverse sinus, inferior to jugular vein)
Bipartisan patella
Superolateral aspect of the knee.
Shoulder injection
Superomedial humeral head For hip- superolateral femoral head
TAPVR
Supracardiac = snowman Infracardiac (into the IVC, can get blocked due to diaphragm)= severe pulmonary edema in newborn 50% associated with asplenia Large PFO or ASD needed to survive
Tc of SCFE
Surgical head pinning
Adrenal cyst
Surgical removal considered if more than 6cm, have symptoms, have nodular or mass like enhancement on CT or MRI, have debri on ultrasound.
what causes increase brown fat for PET
Sympathetic stimulations (ephedrine), beta blockers, cold room.
Popliteal entrapement
Symptomatic entrapement of the popliteal artery 2/2 medial head of the gastrocenmius Normal pulses that worsen with doris/plantarflexion
Synovial chondromatosis vs PVNS
Synovial chondromatosis demonstrates low T1, high T2, enhancing foci, the synovium can enhance, there's erosive changes of the adjacent cortex. PVNS shows low T1, T2, and demonstrates blooming.
DEXA scan
T score-30 year old Z-score- age matched Most reliable in kids is the spine and whole body minus the head When vertebral body is compromised, total hip is next most reliable measurement If patients too fat for machine, use the non dominant radius (distal) or if they have hyperparathyroidism.
Rectal cancer
T1 and T2 mean it hasnt passed the muscularis propria (the rectum has no serosa). T3-> passed the muscularis propria T4-> mesorectal fascia involvement, or less than 1mm margins T3 or above get chemo/radiation (Nigro protocol) Nodes in perirectal fascia >5mm =abnormal
Glomus tumor of distal digit
T1 low, T2 bright, avidly enhances (unlike epidermoid inclusion cyst which is also involves distal phalanx but is usually due to post trauma and doesn't avidly enhance, epidermoid will have wall not central/diffuse enhacement). Glomus tumor usually hits subungal , aka dorsal aspect of finger Epidermoid inclusion also is painless
Increases in magnetic field strength on T1 and T2
T1 time increases by a lot bc of spin-lattice interactions, however T2 barely decreases bc it relies on spin-spin interactions and not very much on the external magnetic field.
Half life
T1/2= 0.693/wavelength Gamma emitters Tc99m=6HRS I-123=13HRS I-131=8DAYS INDIUM, GALLIUM, THALLIUM=3 DAYS Xenon-133=5 DAYS POSITRON EMMITERS: F-18= 110 MINUTES
breast cancer staging
T1=<2cm T2=2-5cm T3=>5cm T4=any size with chest wall fixation, skin involvement and inflammatory breast Ca.
Prostate cancer
T2-no extracapsular extension T3a-extracapsular extension T3b- extracapsular extension with involvement of the seminal vesicles
Prostate metastatic disease screening
T3/T4 cancer, bone pain, Gleason score >8, PSA>20.
whats locally advanced breast cancer
T3: Tumors > 5 cm T4: Tumors with invasion of the chest wall or skin (as seen in inflammatory breast cancer - IBC) N2-3: 4+ axillary lymph nodes or ispilateral supraclavicular, infraclavicular or internal mammary nodal involvement Treatment: These patients may benefit from NEOADJUVANT CHEMOTHERAPY Treatment: - In the past these tumors were synonymous with inoperable breast cancer, but this has changed after the introduction of neoadjuvant therapy. - These patients are first treated with neoadjuvant chemo and/or hormonal therapy. If there is a good response to the neoadjuvant therapy, the next step is surgery and sometimes even breast-conserving surgery is possible. - Before neoadjuvant therapy is given, a clip is placed in the tumor. Sometimes the response is so good that no residual tumor can be found (not detectable by imaging or physical exam - which does not mean there are no residual tumoral cells left behind). - There is current debate whether these patients still need surgery, but currently, most of these patients are treated with BCT (lumpectomy centered on the clip, followed by radiotherapy ).
Hope stress of a balloon catheter
T=PXD, hoop stress is T, increase pressure or diameter and hoop stress will increase linearily.
Doppler shift
TF received-TF initial, if you increase blood velocity towards transducer, then freq increases (TF is distance between the little pulses). Doppler angel depends on Doppler angle Cos(angle)= amount of Doppler shift with 90 degrees is 0. Cos btw 30-60 is optimal.
Carcinoid syndrome valve involvement
TIPS- tricuspid insufficiency and pulmonary stenosis
MRI scan time determinants
TR, matrix size, number of excitations (NEX), decrease them all and scan time decreases. Also decreasing receiver bandwidth will decrease scan time, and increase SNR. Decreasing matrix size will decrease the phase encoding steps and so decreased spatial resolution, also decrease in matrix size leads for some reason also increases SNR. Changing field of view won't affect scan time if matrix size stays the same.
2d fast spin echo time parameters
TRx phase encoding x NEX/ ETL ( echo train length is inversely related to image time, longer ETL also makes the image more T2 heavy) 3D fast spin echo will use the same parameters, with addition of the phase encoding direction in z axis on the numerator side.
Pitch
Table translation distance divided by the beam width
Brain agents
Tc THMPAO, ECD- lipophlic, cross BBB, HMPAO washes out faster and prefers cerebellum and frontal cortex, ECD washes out slower and prefers parietooccipital lobes. Tc DTPA-lipophobic, actsas an angiographic agent, doesn't cross bBB, used for shunt studies, can be used repeatedly also used for brain death. No flow in common carotid. Seizure protocol: Will be hot in ictal state, and cold during interictal state.
Hemangioma scan
Tc labeled rbcS DELAYED BLOOD POOL 30 MINS TO 3 HRS) <2Cm need SPECT HOT spot on delays, with no real hot spot on immediatee flow or immediate pool.
F18 FDG vs Tc-MDP
Tc-MDP will have bone and kidney uptake, it's going to be blurry F18 FDG is super higher resolution, and look like mIP PET FDG PET w/ bone stimulation will look similar to F018 but will have brain uptake.
Dual tracer parathyroid scan
Tc-Sestambi or Thalliuim (both go to the parathyroid and thyroid) + I-123 or Pertechnetate (these only go to the thyroid)= then you subtract and whatevers left is likely the parathyroid adenoma. The Tc99m-pertechnetate is trapped but not organified in the thyroid.
Lymphoscintigraphy
Tc99 sulfur colloid 100-200nm particles, so you really have to filter them, bc if they are too big they wont migrate, and too small they will pass right through the lymph node and not be perceptible for the study. Sentinel lymph node is the first lymph node to drain from injection site Superficial injection go to the axillary lymph nodes (ventral breast drains to axillary chain), deep injections drain to the internal mammary chain).
Gamma energies
Tc99-140kEV I-123- 159 kEV I-131- 365 kEV Ga-67- 100, 200, 300, 400 All PET agents, F-18, Rhobidium= 511kEV Thallium - 80kEV , emits xrays too
CSF studies
TcDTPA for short studies like CSF leaks or shunt studies In-DTPA for things like normal pressure hydrcephalus In DTPA (use dtpa bc it stays inside and doesn't go through ependymal cells or into the brain parenchyma) for NPH, should see trilaminar at 1 hr, Sylvia cistern by 2-6 hrs and convexities by 12hr, prolonged study is indicative of communicationg hydrocephalus.
Which study differentiates stunned from hibernating myocardium
Technetium Sestamibi or Thalium , bc both are positive on PET.
HIDA scan
Technetium99-with iminodiacetic acid stuff No food 4 hrs prior, must have eaten 24 hrs prior (if >24 hr fasting or recent meal (TPN) , give cck or sincalide to excrete some of the excess bile and prevent false positives) Chronic cholecystectomy: 1)delayed filling of the GB (not seen at 1hr , but present at 4 hr) 2) low ef < 30% WITH CCK administration. Cck dose: 0.02 microgram/kg over 60 mins Morphine: 0.04 microgram/kg over 30-60 mins Give the morphine 1 hr post study to speed it up. Neonatal biliary atresia vs hepatitis: if you see tracer in bowel its hepatitis. May have to wait up to 24 hrs. Prime hepatcytes with 5mg/kg x 5 days with phenobarbital.
Male fertility
Temporary and permanent, deterministic effects at 1.5 and 5 Gy , respectively. Temporary and permanent, deterministic effects at 1.5 and 6Gy, respectively in females.
Magic angle
Tendons get bright on short TE (T1, GRE, PD), usually at 55 degrees. Also if you increase the field strength it goes away. Goes away with long TE (T2).
Prostate cancer on FDG PET
Tends to have low count
Esophageal spasm
Tertiary contractions, manommetry >180mmHg
Most common association with DiGeorge syndrome
Tetralogy of Fallot, bicuspid aortic valve
Thallium vs technetium myocardial perfusion studies
Thallium has very high first pass extraction (85%) higher than Tc bases sestamibi and tetrofosmin, thallium redistributes however, so you need to acquire post stress images after around 10 minutes. Bc thallium has a 3 day half-life less amount if injected than technetium agents, also technetium agents are excreted via the liver, so you wait 30-45 minutes to sample technetium agents. Thallium emits 60-80 kEV, via mercury daughters so its background ratio is worse than the 140kev of technetium
Cardiac imaging
Thallium- redistributes , imaging must be done immediately after injection Sestamibi and tetrofosmin- crosses cell via passive diffusion (localized to mitochondria), doesn't redistribute, imaging done in 30-90 mins after injection to allow for background to clear. If there is more uptake in lungs than heart on thallium, it could be triple vessel disease, or high grade LAD or LCX lesions. Chemical stress: regadenoson (dilates the coronaries like adenosine and dipyridamole but less bronchospams). Known left bundle branch blood: gives you a false positive reversible perfusion defect at the septum, dobutamine increases the chances of this even more. Stunned myocardium: normal rest and stress, but poor contracticlity, acute events, gets better in weeks Hibernating- chronic ischemic, looks like scar, abnormal rest and stress uptake. But this will redistribute thallium, and pick up PET (even more than surroundings). Thallium clears more slowly from regions supplied by stenosis vessels than from normal myocardial regions. Normal thallium washout is 30% at 3 hrs and 35% at 4 hrs.
2D vs 3D PET acquisition?
The 3D mode (septa retracted) increases coincidence efficiency by about 5X in comparison to a 2D acquisition (septa extended) at the expense of increasing randoms and scattered coincidences and system dead-time. It has been shown that the maximum is reached by the NEC in 3D at a lower activity concentration than in 2D as expected from the behavior of the true coincidence rate.
2D vs 3D PET acquisition?
The 3D mode (septa retracted) increases coincidence efficiency by about 5X in comparison to a 2D acquisition (septa extended) at the expense of increasing randoms and scattered coincidences and system dead-time. It has been shown that the maximum is reached by the NEC in 3D at a lower activity concentration than in 2D as expected from the behavior of the true coincidence rate. 3d has more dead time occurrence (so use LSO or more PMTs), more random events, and more scatter.
2D vs 3D PET acquisition?
The 3D mode (septa retracted) increases coincidence efficiency by about 5X in comparison to a 2D acquisition (septa extended) at the expense of increasing randoms and scattered coincidences and system dead-time. It has been shown that the maximum is reached by the NEC in 3D at a lower activity concentration than in 2D as expected from the behavior of the true coincidence rate. Disadvantages of 3D: more dead time, more random events, scatter. How to fix dead time: crystals with faster scintillation time (LSO), or you can add more PMTs.
Indirect Flat panel detector
The CsI scintillator turns photon into light, the light has a tendency to dispersed, creating lateral dispersion, the thicker the crystal the worse, you cant make the crystal too thin bc then light goes right through. Not present in direct panel detectors (don't use scintillators ). Direct uses amorphous selenium (photoconductor) Fill factor= area of the detetor which is sensitive to x-rays (in relation to the entire detector area ), the higher the field factor the more efficient. Direct panel detectors have 100% essentially, but indirect using lateral dispersion and such don't. Because DR have a better fill factor (near 100%), that means they are more efficient. You can infer DR has a higher DQE.
Why is hemochromatosis hypointense on in phase
The GRE in phase has longer TE, and hence greater T2star susceptibility compared to the out of phase, making iron appear hypointense on in phase.
Modulation Transfer Function (MTF)
The ability of a system to record available spatial frequencies that are as accurate as the original date that struck the receptor, it's never going to be 100%, it depends on the electronics of the system used. can compare different machines to see which is best using this principle.
phi angle
The angle between the gastric sleeve and the vertebra , normal is between 4-58 degrees.
Dynamic range ultrasound
The dynamic range is the ratio of the LAREST to the SMALLEST echoes that a scanner can respond to The HIGHER the dynamic range, the SMOOTHER the image appears, can differentiate the borders of kidney better The LOWER the dynamic range, the MORE CONTRAST the image has think of dynamic range like this: if you are able to detect more frequencies then things will look more smooth.
Dynamic range ultrasound
The dynamic range is the ratio of the LARGEST to the SMALLEST echoes that a scanner can respond to The HIGHER the dynamic range, the SMOOTHER the image appears The LOWER the dynamic range, the MORE CONTRAST the image has think of dynamic range like this: if you are able to detect more frequencies then things will look more smooth. Increasing dynamic range will be like increasing the window on CT though, the contrast will suffer.
anode angle
The greater the angle the less the heel effect. The less the angle, the more steep, the greater the heel effect. Also the greater the angle the greater the effective focal spot size. If you increase anode angle you also get more point sources from the metal, this leads to more point source which increase image blurriness, aka decreased resolution.
kVp and contrast
The higher the kVp, the longer the scale of contrast on the film. The overall Contrast is decreased bc now the high energy photons can penetrate bone and lung more so than lower kvp where the bone can absorb more X-rays then the lung and there will be a bigger difference in the two tissues next to each other aka better contrast. Also higher kvp less dose bc less weak energy electrons that can linger in the patient and not go through. increasing kvp compared to mA results in lower dose but lower contrast (energies go through the bone and lung better) increasing kvp also decreases dose in mammo bs less will be absorbed by breast, but at the expense of less image resolution. (using rhodium instead of moly targer, or rhod instead of moly filter will also result in a stronger beam, and less radiation bc less will stay in breast tissue).
Amniotic band syndrome
The mamebranes of teh amniotic sac and chorionic space typically remain separated by a thin layer of lfuid until 14-16 weeks. If the amnion gets disrupted before, the fetus crosses into the chorionic cavity and gets tangled up in the fibrous bands.
Matrix size in MRI
The matrix size is the number of frequency encoding steps in one dimension and phase encoding steps in the other dimension. Your goal is to fill k space, if you use the longest matrix as the frequency encoding phase (lets say in a 128 x 256 matrix you pick the 256) then you just repeat 128 times, instead of 256 times, so you cut down the time by a lot without diminishing image quality.
Specific absorption rate (SAR)
The number of Watts of RF energy per kilogram of body weight in an imaging sequence 4W/kg for whole body in 15 mins 3W/kg for head in 10 mins -avg RF pulse deposited in the body and converted into heat, should not exceed 1 celsius.
Time required to acquire image
The number of phase encoding steps (should be the image repetition time and that should be shortest x TR. to optimize time, the smaller matrix should be the phase encoding phase.
Beam hardening
The phenomenon whereby low-energy photons are absorbed as the x-ray beam passes through an object, resulting in an increase in the average photon energy of the beam. Usually occurs around the middle of the head after passing through bone, this leads to the center of the head appearing more dark as the avg energy of these photons is increased when it reaches detector in comparison to periphery. Fix by using bow tie filter , or pre hardening the beam(remove lower energy components), also calibration correction, or itirrative correction.
Shimming
The process of improving the homogeneity of the magnetic field, either through active shimming (use of shim coils) or passive shimming (adding or removing steel from the magnet).can happen with fat sat in breast.
Corrected D-transposition of the great vessels
The pulmonary trunk drapes over the aorta, which is normally in front of the pulmonary artery (LeCompte Maneuver with Jatene arterial switch).
Leakage radiation
The radiation comes out in all directions from the tube or tube head due to malfunction or leakage Should not exceed 1mGy/hr at 1 meter from source.
Oxygen Enhancement Ratio (OER)
The ratio of the radiation dose required to cause a particular biologic response of cells or organisms in any oxygen-deprived environment to the radiation dose required to cause an identical response under normally oxygenated conditions. Low LET(photons, gamma rays) it matters, if high LET biological damage without and with oxygen is same.
skin problems based on radiation
The reactor creates radiation, EVERY SATURDAY THE DAMN MACHINE STOPS (amount in Gy), from 2-24 Gy in range. Early squamation onset in hrs, rest in weeks. E-early erythema - 2 S-evere erythema -6 T-elangiectasia - 10 D-ry squamation- 13 M-oist squamation/ulceration -18 S-econdary ulceration -24
Rotator cuff interval
The triangular space between the tendons of subscapularis and supraspinatus and the base of the coracoid process., where the biceps tendon traverses.
Screens in film radiography
The use of screens leads to more scatter of photons, and hence more image blur Shorter exposure leads to better resolution due to less motion
Film latitude (dynamic range) and air kerma
The wider the latitude,the more the air kerma range that results in good film contrast.
Pagets vs fibrous dysplasia
There's cortical and trabecular thickening with Paget's, while there is more thin cortex and fibrous matrix with Fibrous dysplasia.
Which treatment is potentially curative for HCC
Thermal ablation (usually for tumors <3cm , and up to 3 tumors), TACE and Yitrium are not curative Surgery is also curative of course Ablative margin approx. 5-10mm
Ultrasound safety
Thermal index-ratio of total acoustic power / power needed to raise tissue by one degree Celsius , the larger the more heating in tissue. a. thermal induced damage is threshold phenomenon b. spectral doppler produces most heat out of all modes c. related to increased frequency as well Mechanical index-probability of cavitation, microbubbles can destroy cells/denature cells. Proportional to time of exposure and whether you are scanning around not just in one tissue all the time. a. cavitation is most likely to increase with low frequency and high pressure. TI >1.0 or MI >0.5 = risk benefit decision
Lead positioning
Thick sclerotic line around the metaphysis
Transverse growth lines
Thin horizontal lines, likely secondary to osteoblasts activity during recovery phase after an illness. Metaphysical lines —> dense lines at zone of provisional calcification immediately adjacent to the physis. Stress fix—> lucency in the cortex of the bone Lead lines—> dense metaphyseal lines (seen in knee and wrist)
Aplastic/hypoplastic humeral head in a kid
Think about erb's palsy from c5-c6 hit aka brachial plexus during delivery for being big
Esophageal pseudodiverticulosis
Think chronic reflux esophagitis. The "psuedodiverticula" are dilated submucosal glands
Transient osteoporosis of the hip
Think pregnant woman in 3rd trimester with left hip pain. See osteopenia on radiograph, edema on MRI, hot on bone scan. No dark band on t1 to indicate AVN or insufficiency fracture (although they are predisposed to insufficiency fxs)
Slice thickness in MRI
Thinner slicer with steep(large) slice selection gradient, and thin transmit bandwidth. Thicker slicer with shallow (small) slice selection gradient, and thick transmit bandwidth.
Bouveret syndrome
This is another name for gallstone ileus within the duodeunum You are going to see an obstructing stone in the duodenum, large stomach, and dilation of the CBD
Moderator band
This structure stretches from a papillary muscle on the interventricular septum to the wall of the right ventricle. Functionally it is important because it conducts impulses between these two regions on the heart, thereby coordinating the contraction of the cells and it may also help prevent overdistention of the ventricular wall
Microvascular obstruction
Thisis going to be dark islands in a sea of EARLY (FIRST 25 SECS) gadollineum enhancement This is a POOR prognostic factor This is NOT seen in chronic infarct.
MEN 1
Thymic carcinoid is associated with MEN 1, P(pituitary), P(pancreas), P(parathyroid), and thymic carcinoid too. thymic carcinoid affects men more than women (3:1), and it produces ACTH, resulting in Cushing's syndrome.
Blount's disease
Tibia Varus (at the knee). Seen after 2, not the classic normal varus that kids get at first at the metaphysis, this is at the knee itself.
Table time in MRI
Time=TR X Phase matrix x Nex TR=time between RF pulses Phase matrix- how many phase encoding steps Nex-numberof times each set of phase encoding steps is repeated This is applicable to spin echo and gradient echo sequences. Exception , fast spin echo = 1/echo train length; and 3D (instead of slices you use blocks, has better spatial resolution and SNR), but 3D takes too long. 3D time: TR X Phase matrix x Nex x #slices
Tesla strength and Lemmar frequency
To affect Lemmnar frequency of hydrogen atoms, the radio-frequency pulse in a 1 Tesla needs to be 42 MHz, in a 6 T (6 x 42= 252mHz).
Limiting spatial resolution (LSR)
To calculate, number of samples per row divided by length, then divide that by two to get the limiting spatial resolution (which is half the sampling frequency)
The aliasing artifact in ultrasound
To correct, decrease the pulse frequency, increase velocity scale, increase PRF (decrease pulse repetition period), and get closer to the object that way signal comes back faster rather than signal taking a long time so other signal returns and the location calculation is messed up.
Why is blood dark on spin echo sequences
To create signal you need the 90 degree and then the 180 degree pulse, bloods moving too fast, so it wont receive both, hence it'll be dark.
Loetz Dietz
Tortuous aorta and branches, can leads to dissections, ruptures
Small left colon (meconium plug) syndrome
Transient functional colonic obstruction, relieved by contrast enema. Seen in infants of diabetic mothers, or moms who have gotten magnesium sulfate for preeclampsia.
Transient vs secular equilibrium
Transient is when the daughters half life is slightly smaller than the parent half life. Secular equilibrium is when the parent half life is much longer than the daughter half life.
Splenic pseudoaneurysm
Treated when 2-3cm in size Post pregnancy can happen, increase risk
Fat embolization syndrome
Triad of rash, AMS, and SOB 1-2 days after femur fracture Lungs have GG appearance that looks like edema. No filling defect on CTA. Improves in 1-3 weeks if patients survives.
Ebstein's anomaly
Tricuspid flaps fused to inside of right ventricle; creates constant opening between atrium & ventricle, atrialization of the right ventricle. Massive box shaped hearts. moms on lithium.
Troland and labbe
Troland connects the superficial sagittal sinus to the superficial middle cerebral vein Labbe connects the superficial cerebral vein to the transverse sinus Troland on top, Labbe on the bottom
bicuspid aortic valve
Turner's syndrome (coarctation and bicuspid valve), cystic medial necrosis (Marfans), ADPKD.
Most specific sign of ovarian torsion
Twisted vascular pedicle
High probability v/q scan(80-100%)
Two large mismatch defects, or equivalent in moderate size (4 moderate segmental mismatch defects)
Stocker classification of CCAM
Type 1 is a giant cyst Type 2 is multicysts (classic) Type 3 multi tiny cysts that are imperceptible lesion is resected bc of super low risk of cancer
Types stress fracture
Type 2- periosteal edema Type 3-periosteal and bone marrow T1/t2 changes Type 4-actual fracture fragment and surrounding edema
Types of choledocal cysts
Type I (80-90%)= extrahepatic duct cyst Type II =extrahepatic duct true diverticulum Type III= choledochocele Type IV= both intra and extrahepatic duct dilatation Type V= carolis' (intrahepatic duct dilatation only) Type i and iii have higher risk of cholangiocarcioma
Types of urethral injuries
Type I -stretching of membranous urethra Type II- injury to membranous urethra but not UG diaphragm Type III- injury to membranous urethra and UG diaphragm (ant and post injury) Type IV- bladder neck injury extending to the urethra Type V-injury to bulbar or penile urethra (anterior injury) The inferior margin of the obturator foramina serve as useful fixed an atomic landmarks for the level of the urogenital diaphragm at the junction of the anterior and posterior urethra. A bulbar urethral stricture shows a cone well below the inferior margin for eh obturator foramina. The inferior obturator foramina is the landmark of the UG diaphragm (separates ant from post urethra).`
Chemical shift artifact
Type I appears as a bright or black band at the interfaces of fatty tissue surrounded by non-fatty tissue. The bright band will present on one side of the fatty tissue and the black band will present on the opposite side. Origin: Different resonant frequency of fat and water, one of the few artifacts found in the frequency encoding direction. Direction: FREQUENCY ENCODE DIRECTION! TYPE 1. Solution: Invert the phase-encode and frequency-encode directions to view the pathology better, increase receiver bandwidth (decrease SNR), decrease TE (both these last 2 decrease SNR).
Types of AC joint injuries
Type I is a sprain of the AC joint ligemants Type II is a rupture of the AC joint ligaments Type III is a rupture of the coracoclavicular ligaments. This is surgical, type I/II is not.
Le Fort fractures
Type I-upper lip, lower lateral nasal bone Type II-maxilla and nasal bone, inferior orbital rim/floor Type III- lateral orbital rim and zygoma
dual energy Ct
Type of CT that alternates between 140 and 80 kev x-rays, two x ray sources simultaneously rotating 180 degrees. higher rads than single dose ct. can use dual energy to do different HU, can use for liver cysts, renal cysts, and uric acid stones. dual source=more dose than a single source CT
Typical entrance radiation doses
Typical air kerma for x rays in the "ones" 3mGy, fluoro in the "ten" 30-50mGy, and IR or cardiac cath in the "hundreds" 200-300mGy/min.
X linked adrenoleukodystrophy
Typically a normal boy that now shows regression, they have typically periventricular parietooccipital white matter changes, also thalamus and posterior limb of internal capsule. Alexaner's disease would show more bifrontal invovlement.
Parosteal osteosarcoma
Typically arises from the posterior aspect of the distal femur, best prognosis of all the osteosarcomas
Simple bone cyst
Typically centrally located, intermaedullary, can have fallen bone fragment sign. Most commonly in the proximal humerus, femur, or proximal tibia in the pediatric population.
Rim enhancement on breast mri
Typically invasive ductal carcinoma (40%), fat necrosis, inflammatory cyst; not fibroadenoma.
Most common congenital anomaly of the GU tract
UPJ obstruction. Look for vessels crossing the UPJ tract, changes management.
Local breast lump and less than 30
Ultrasounds, no need for mammo unless there's something suspicious in ultrasound
CTDIvol in different patients
Underestimated for ped patients Overestimated for big fat patients
Normal adrenal mass protocol
Unenhanced, 1 minute post contrast, 15 minute delayed contrast In general, operative resection is considered for most large (>4cm) solid adrenal masses in pits without a known malignancy, regardless of lipid content or washout calculations.
Post op gas time period
Up to 10 days in plain film , and 2 weeks in CT. Passed that start being suspicious for anastomotic leaks, etc.
Panda sign
Uptake of gallium 67 on the parotid and lacrimal glands bl, associated with sarcoidosis , but also in lymphoma, HIV, and Sjorgens.
Deflux injection
Urologic treatment to try and treat vesivoureteral reflux, results in an echogenic mound near the UVJ.
GRE sequences
Use a short flip angle, don't rely on 180 degrees, rely on something called bipolar readout gradient Relies then heavily on T2 star Susceptibile to a lot of field inhomogeneity and susceptibility artifacts, also signal to noise sucks (want a long TR for increased SNR).
Dose calibrators
Use an ion chamber to detect and measure radiation, used before administering a specific dose of radio pharmaceutical
Cardiac mri sine images
Use gradient echo MRI images, like SSPF
Direct flat panel detectors
Use metals such as selenium, which works best at low energies, bc of low k shell energy of selenium
How to compensate for magnification in mammography
Use of a smaller filament, to create a smaller focal spot size to compensate for the geometric blur by the increased magnification. Use 0.1mm, instead of 0.3mm, but you end up heating the anode more, but you have to increase exposure Time to avoid the heating. Magnification increases effective resolution, and you decrease quantum mottle which decreased noise, so increase CNR Magnification leads to constant dose, you bringing breast closer to source, but you decreased Bucky factor. Steps: 1. Place air gap (plastic edge) under breast 2. Switch to smaller filament 3. Remove grid. Air gap allows for geometric magnification, but also causes geometric blur Smaller filament decreases focal spot size, which compensates for geometric blur Air gap allows scattered radiation to diverge away and escape detector, grid isn't needed, saving dose. Magnification decreases scatter, hence increasing contrast-to-noise ratio (CNR), bc the air gap lets more scattered radiation escape before it hits the detector. Less scatter means the grid can be removed.
Indirect flat panel detectors
Use scintillators to emit light
MDP
Used for bone studies, 15-25mCi injected, the pertechnetate is reduced by stannous ions, if not enough, you get free Tec (which involves salivary, thyroid, and stomach uptake). Factors that affect uptake: osteoblastic activity, blood flow. Marked uptake in sutures may be due to renal osteodystrophy, renal cortex hotter than adjacent lumbar spine is seen with hemochromatosis, diffuse hot kidneys (think chemotherapy). Liver uptake: hepatoma, not FNH, could be from to much Al3+ in Tc prep contamination, amyloidosis, and liver necrosis. spleen uptake: autoinfraction in sticklers Sacrum: honda sign, insuff. Fix. lung uptake: super nonspecific Diffuse decrease bone uptake: free tc (check salivary, thyroid, and stomach), and/or biphosphonate therapy (like kids with osteogenesis imperfects Tc) Fix in elderly: may be negative up to aa week. Muscle: hot quads, shoulders, etc. in rhabdomyolysis. Flare phenomenon: hotter bone scan, on plain film/ct you should see lesions getting more sclerotic, it can last weeks to 2-3 months. Heterotopic ossification: can see if lesions still active, between to wait till its cold to respects, less chance it comes back. hypertrophic osteoarthropathy: tramline along the periosteum of long bones. Think lung cancer. Pa gets: involved both the vertebral bodies and posterior elements, Fx areusually the vertebral bodies only. AVN: early and late is cold, middle (repairing can be hot). HOT bone lesions: fibrous dysplasia, giant cell tumor, ABC, osteoblastoma, osteoma osteoma (double hot uptake) COLD bone lesions: bone cysts without fox. Superscan from mets vs metabolic suprescan: both have absent kidneys, but the metabolic one will have hot skull. Triple phase: cellulitis (hot on flow and blood pool but not delayed) vs osteomyelitis (hot on all 3 phases) Triple phase hot: reflex sympathetic dystrophy, osteomyelitis, osteoma osteoma, tumor, Fracture, Charcot joint. Contamination summary: Don't put stannous ions-free tec (stomach, thyroid, salivary glands) Put air in syringe -free tec Put in water=Tc Dioxide and Sun Colloid (will see uptake in the liver
Technetium 99-HMPAO
Used for brain imaging, can be used for seizures, where you have increased uptake during seizures and decreased signal interictally, like PET scan. More sensitive for intraictal event in extratemporal seizures compared to PET. Usually administered 1 hr after seizures to show ictal activity, then done again 2 days later which should show decreased uptake in the interictal period.
Bar phantom
Used for gamma planar and spect Spatial resolution and linearity, done weekly
Geiger muller counters
Used for handheld detection surverys use a Geiger Muller probe which uses a gas chamber to detect ionizing radiation. It exponentially increases signal in gas , its not 1:1. Although its very sensitive, theres DEAD TIME= it can be vulnerable to overload by a large dose of radiation, ionization must dissipate before it can respond again. Max dose is 100mR/h.
Technetium DMSA vs MAG3 and DTPA
Used to assess cortical activity, less than 5% gets excreted through urine , like DTPA or MAG3.Best agent to assess renal split function.
Dose calibrators
Used to detect radiation before giving it to patient Rely on ionization gas chamber to measure radiation
Well counters
Used to measure radiation in small samples, such as wipe test, rely on sodium iodide detector, has a small hole in middle where you dump the material to measure, but easily saturated. thyroid probe is same thing.
180 RF pulse
Used to suppress T2 star artifAct., you do it when the T2 signal starts dephasing. This is not present on GRE images and that's why there's T2*artifact there.
Computed radiography (CR) detector of xrays
Uses a photostimulable phosphor that moves an electron from ground to metastable state, after it hits by red light in machine, the Red light activates, then the electron releases blue light which is picked up. To reset the whole system you shine bright white light.
Indirect digital detector
Uses a scintillator, which converts x rays to light and then the light is sensed by the ccd camera or photodiode which then sends the digital signal to pc through thin film transitors. Btw the system uses CsI to convert x rays to light, it's also used in nuclear medicine (NaI, N for nukes).
Time of Flight MRA
Uses gradient echo sequences, where saturation pulse is employed to null venous or arterial blood flow. Has small voxel size. 3D has even better spatial resolution, SNR, and shorter imaging time. Time of flight is also faster and less sensitive to signal loss from turbulent vessels than phase contrast MRA.
Time of flight in PET
Uses quick detection which helps estimate the actual point of annihilation (best in large objects with low contrast) - Improves spatial resolution and image contrast * SUV measurements with TOF are HIGHER than standard PET
Dual energy imaging
Uses two diff x ray beams and detectors to get a soft tissue and typically a bone window as well. They are more susceptible to noise. Temporal resolution is increased (why its used in cardiac imaging).
Subcortical arteriosclerotic encephalopahty
Usuallty from hypertension, gets subcortical infarcts, high T2/flair in the temporal regions , spares occipital, and also spares the u fibers, similar to CADASIL, except CADASIL would be in pts around 40 yo with migraines.
Bucket handle tear of meniscus
Usually 2/2 vertical longitudinal tear , results in medial part of meniscus at the intercondylar notch and giving the double PCL sign. Double PCL only happens with the medial meniscus, bc the ACL would prevent the lateral meniscus from going back into the posterior intercondylar notch.
Laryngeal cancer
Usually Glottic or supraglottic. If there's involvement of the cricoid cartilage (can only really be seen by mass on both sides of the cricoid cartilage ), paralysis of vocal cords, or paraglottic /trans glottic involvement then there's no conserving surgery. You need intact cricoid for surgery to stabilize. So all these makes is T3. Cricoid is inside the thyroid cartilage, it's only circular cartilage in the neck.
Eosinophilic esophagitis
Usually all portions of the esophagus, involves all walls of the esophagus, thickened rings Feline esophagus involves the mucosa, and lower 2/3 of the esophagus, due to muscular mucosa issues actually
Kawasakis
Usually associated with aneurysms of the coronaries , diarrhea, gi distress, hydrops of the gallbladder. Echocardiogram is the best initial and follow up evaluation for Kawasaki's evaluation of the heart.
Women sp mantle radiation
Usually for Hodgkin lymphoma Begin breast mammograms 8 years since tx or at 30 whichever comes later, additional should have an MRI as well, >20% risk.
Juxtacortical chondroma
Usually found at the humerus, lytic cortical lesion with periosteal reaction trying to lay down new bone, with lateral lytic aspect not completely covered by periosteum; can be painful. Tx surgical excision alone. Male predilections, usually proximal humerus or distal femur.
Subependymoma
Usually intraventricular, doesnt calcify or enhance as much as ependymoma, seen in >15 yo, usually minimal enhancment. Low risk of involving other structures.
endometrial cancer
Usually iso T1, high T2, and less enhancement than the adjacent myometrium Stage 1a <50% myometrial invasion, stage 1b >50% myometrial invasion Stage II cervical stroma invasion (the cervical stroma is dark on post contrast imaging) It's adenocarcinoma (like urethral diverticulum)
Mullerian ducts
Uterus, Fallopian tubes, ovaries, upper 2/3 vagina Urogenital sinus makes prostate and lower 1/3 of vagina.
VACTERL
V-vertebral, A-anal, Cardiac, T-racheoesophageal, R-enal, L-limb abnormalities. Need 3 or more for symptom. N-type TE fistula is most common , blind esophagus and distal trachea attaches to lower esophagus.
Ecmo catheters
VA- right atrium and aorta catheter. For this one oxygenated blood taken from right atrium goes back to the aortic arch. You sacrifice the IJ and the carotid with big catheters, increased risk of neurological ischemia. VV- blood is taken out, oxygenated , and returned to the right atrium . Another complication is hemorrhage in ecmo (why they do head ultrasound before and during), bc the patient is anti coagulated.
Pyelonephritis in an infant
VCUG should be performed after a short course of antibiotics
endolymphatic sac tumor
VHL, most are however sporadic, see calcs on CT, MRI bright T2 and avidly enhancing paragangliomas can hit jugular canal (usually present with vagal n hit, so hoarseness, etc), also T2 bright and avidly enhancing.
Subarachnoid hemorrhage most common cause of morbidity/mortality not taking into account the bleed
Vasospasm has surpassed rebleeding.
Neonatal renal artery and vein thrombosis
Vein- 2/2 maternal diabetes Artery-2/2 umbilical artery catheter, will present with htn.
Post mi complication timing
Ventricular aneurysm occur months after (the thin myocardium gets the high ventricular flow and so overtime it bulges out) Ventricular pseudoaneurysm/wall rupture occurs 3-5 days after (true aneurysm-mouth wider than body takes months bc it requires remodeling, false aneurysm-mouth is narrower compared to body) Dressler's syndrome (post MI pericarditis 4-6 weeks or more after) papillary muscle rupture 2-7days
Vertebral osteonecrosis
Vertebral collapse associated with intravertebral air
McKittrick-Wheelock syndrome
Villous adenoma leading to mucus diarrhea and severe electrolyte imbalance.
Dose length product
Volumetric CTDI x scan length (Volumetric CTDI= weighted CTDI/pitch)
Breast feeding and PET
Wait 8 hrs, FGD doesn't go to the breast milk, but as a precaution.
Sarcoidosis
Wall thickening in the heart, can show myocardial enhancement, patchy or subepicardial enhancement.
Pseudoaneurysm and thrombin
Want a a narrow neck, 2-3cm aneurysms are fine, contraindictations are many but look for an AVF, the thrombin will go to the vein. Wide neck is also contraindicated. If around 1cm, follow up is usually preferred. Place the needle in the pseudoaneurysm sac, away from the neck.
Grid controlled fluoroscopy
Way of turning off the anode filament fast using a little cup around the filament, to suck electrons out. 1-2kvp is applied to cup to break the mA current in the tube. Exposures started by removing the neg charge from the grid, and then terminated by restoring the neg charge which will keep electrons away.
MQSA quality control on phantom
Weekly
Nuclear medicine bar phantom
Weekly To assess linearity and spatial resolution
Volume CTDI
Weighted CTDI / pitch Greater overlap the greater the pitch, the lesser the volume CTDI. Invariant to scan length
Refraction
When a wave enters a new medium at an angle, one side of the wave changes speed before the other side, causing the wave to bend. Due to differences in velocity of the inter phases, and creates misregistration on the probe.
Limb ischemia
When acute motor and sensory functions is gone, surgery is warranted.
How often to test the stereotactic biopsy machine?
When installed, and yearly, called "localization accuracy test"
Pancost tumor
When is it unresectable? -brachial plexus invovlement above T1 -more than 50%vertebral body size -diaphragmatic paralysis ( means C3-C4 are involved, keeps the diaphragm off the floor) - distal nodes/mets
PET
When to do pet on patients getting treatment ? 2-3 weeks post chemo, and 8-10 weeks post radiation to prevent false cool down effect or false positive inflammation induced events.
Radiation transpot
White 1: no special handling, surface dose rate <0.5 mRem/hr, 1 meter about 0 mRem/hr Yellow 2: special handling, surface dose <50mRem/hr, 1 meter <1mRem/hr Yellow 3: special handling, surface dose <200mRem/hr, 1 meter <10mRem/hr Transport index=measured max dose at 1 meter. White has none, yellow 2 <1mRem/hr, yellow 3 >1mRem /hr. Common carriers: track that carries regular packages and radioactive material. The T.I. Should not exceed 10mRem/hr. Surface rate should not exceeed 200mRem. Multiple packages: should not exceed 50mRem combined.
Enteric duplication cysts
Will have gut signature, if not, big as cystic lesion could be an omental cyst. Gut signature will show hyper/hypoechoic signal. Represent differs layers of bowel. 30% time associated with vertebral anomalies.
Tear of the biceps at the bicipetal groove
Will involve the transverse humeral ligament and the subscapularis tendon Usually it can migrate medially if just the transverse humeral ligament is hit, and sit anterior to the subscapularis tendon. Once the subscapularis is also torn, then the biceps tendon will be in the glenohumeral joint space.
NRC reportable events
Within 24 hrs, and written within 15 days. if dose exceed 50mSv per whole body (same as annual worker max dose), or more than 500mSv per specific organ.
Non mass enhancement
Worse pattern is the segmental, conical in shape with apex pointing towards the nipple, with representation of multiple ductal systems .
Post menopausal women with cyst >1cm-7cm
Year follow up
Follow up for thymoma , sp resection
Yearly ct for 5 years, then alternating ct and plain film till year 11, most indolent once's return after year 5. invasive thymoma with involvement of the pericardium requires noadjuvant chemo and surgery with post op radiation, if its not involving the myocardium then just surgery alone. can look like mesothelioma with thickened pleural nodularity. thymoma's very hot on PET, cutoff of 5 SUV even
Cardiac CTA
You can decrease dose by using tube modulation, decreases or increasing mA with the cardiac cycle (i.e. increase mA during diastole ).
Pseudoaneurysm off the celiac?
You can do prod and distal coil embolization if the inferior pancreaticoduoneal (first branch of SMA is patent) which will serve as collateral to the celiac trunk.
B-minus decay
You convert a neutron into a proton , and release an electron which interacts with other electrons close by. I-131 uses this, why it serves as a treatment option.
ADC
You need B factor-type of tissue weighting for diffusion studies. You need B0 and B1000 to use the two to calculate the ADC map, if it was just for DWI you just needed the B1000.
Zenckers diverticulum vs Killian-Jameson
Zenkers is falsae diverticulum, due to killina triangle dehiscence, this is above the cricopharyngeus (true upper esophageal sphincter) you get it at teh hypopharynx Killina-Jameson diverticulum is in the cervical esophagus, below the cricopharyngeus
Resolution of pneumonia on X-ray based on age
`6 weeks for young, up to 3 months for elderly
Juvenile arthritis
a chronic and painful muscular condition seen in children Most common site of ankylosis is the carpal bones In the spine, results in joint space narrowing of the synovial line joints, with loss of AP diameter in vertebral bodies and loss of intervertebral disc space height. Most common at c2-c3, cannot have lower cervical involvement without upper cervical involvement.
full width at half maximum (FWHM)
a measure of resolution equal to the width of an image line source at points where the intensity is reduced to half the maximum; represents the distance between two points on the slice sensitivity profile curve whose intensity is 50% of the peak 1/ (2 x FWHM) = line pairs/mm
multicystic dysplastic kidney disease
a renal disease thought to be caused by an early renal obstruction; leads to the development of multiple noncommunicating cysts of varying sizes in the renal fossa. 50% will have contralateral upv or vuj reflux or obstruction, so kids need VCUG No need to remove the kidney, no increased malignancy in dysplastic kidney
Struma ovarii
a teratoma composed primarily of thyroid tissue Very very low T2 signal is indicativ of colloid.
Unicameral bone cyst
a true fluid-filled cyst with a wall of fibrous tissue that most often occurs in the proximal humerus or femur at the metaphysis Tx is with curettage and cement or intralesional steroid injection, consensus on which is best is not definite, if the lesion is big and at risk for pathologic fracture.
cochlear promontory mass
aberrant ICA, glomus tympanicum, congenital cholestelatoma , not acquired(thats in prussacs space).
macrocrania
abnormal increase in the size of the skull See prominent of subarachnoid space in the frontal lobe interhemispheric region primarily Will see cortical veins coursing, differentiating from subdural hygroma or subdural blood
TIPS
absolute contraindication is elevated right heart pressure (>5mmHg) - the pressure in the TIPS should be less than 12mmHg -evaluation of normal TIPS: reverse flow in left/right portal veins is normal, flow in stent should be btw 90-190cm/s stenosis/malfunction: - >200cm intrastent velocity -low portal vein velocity (<30cm/s) - temporal increase/decrease in velocity by more than 50 cm/s. -new or increased ascites -most focal occlusion occur in the hepatic/stent side. PSG>12mmHg- NEXT STEP= tx the stenosis (usually hepatic venous side)
damping/backing material
absorbing layer in transducer which shortens the time duration of an ultrasound pulse Decreases sensitivity, picks up less echoes Improves axial resolution Increases bandwidth (range of frequencies), a 4MhZ transducer would send out from 3-6Mhz for example. Made up of tungsten
how to decrease metallic artifact on CT
acquire with thinner slices, reconstruct with thicker slices, increase kVP or use dual energy CT, can increase mAs to decrease photon starvation, collimation also helps reduce volume averaging.
Cataract development
acute exposure threshold- 0.5-2.5Gy, annual dose rate limit 150mSv.
acute vs subacute eosinophilic pneumonia
acute has high eosinophils in bronchoalveolar lavage, but not in blood, and after steroid taper it doesnt usually relapse.
air kerma vs air kerma product
air kerma deterministic effects (measurable, predictable , like how much radiation before you get cataract), decreases by 1/r^2 air kerma product stochastic effect (how much air kerma per area covered), doesnt change with distance bc as you move further away you decrease air kerma but you increase the area covered as the electrons dissipate away. KAP does decrease with collimation bc we decrease the area sampled.
air kerma in DSA vs fluoro
air kerma in DSA is higher than air kerma in fluoro air kerma in fluoro is less than air kerma in radiography
electronic mag and air kerma
air kerma increases, but kap stays same bc although you increased dose, the area covered is smaller.
grid tagging
allows for assessment of intramyocardial motion, i.e. in HCOM, which can be used to measure strain
Spigelian hernia
along the semilunar line throug the transversus abdominis aponeurosis Semilunar line is lateral to the rectus abdominis musculature.
lower lobe emphysema
alpha 1 antitrypsin, ritalin lung (hypeinflation of lower lobes with destruction of secondary lobar units), or Swyer James (but Swyer James presents with volume loss, ritalin lung creastes hyperexpanded lungs).
collimation in fluoro
always increases contrast, but decreases KAP. collimation reduces the area of the x-ray beam, decreasing the amount of scattered radiation that can potentially reach the image receptoy, by reducing scatter, collimation should increase or improve image contrast. also collimation reduces patient dose.
equivalent dose
amount of DNA damage by different radiation sources, xrays or gamma rays, used in sV.
Mechanical index (MI)
an estimate of the amount of contrast harmonics (depends on the frequency of transmitted sound & the pressure of the sound wave) Inversely related to frequency Used in contrast ultrasound(where cavitation are desired) Decreased by increasing the focal spot, and decreasing the ultrasound beam output.
Geiger-Muller counter
an instrument that detects and measures the intensity of radiation by counting the number of electric pulses that pass between the anode and the cathode in a tube filled with gas, very sensitive, it exponentially increases, long dead time, usually used just to see if there's radiation in an area.
Sertoli cell tumor
androblastoma from sex cord stroma, makes androgens. Prepubertal females get virilization . S for sir. associated with Carney's complex (apparently 100% get Sertoli cell tumors?)
pedicle aneurysm
aneurysm of the artery feeding the AVM, greater risk of rupture than the aneurysms within the AVM itself.
best kvp for contrast studies
angio=70kvp, half of energy is 35kvp close to iodine k edge of 33 ct angio =100 kvp fluoro=90-110 kvp
beam-hardening artifacts
artifacts that result from lower-energy photons being preferentially absorbed, leaving higher-intensity photons to strike the detector array Usually at interphases btw dense and soft tissue like temporal bone and brain
most common heart anomaly with ebsteins
asd, due to distention of the right atrium.
most common complication of zenker's
aspiration /aspiration pneumonia
Fetal Biophysical Profile
assesses five biophysical variables; fetal breathing movement, fetal movement of body or limbs, fetal tone extension/flexion of extremities), amniotic fluid volume (>2cm), and reactive NST. Oligo is less than 5cm in 4 biggest pockets, poly is >20cm.
3 chamber view
assesses left ventricular outflow tract , good to assess aortic valve issues
Ostium primum defect
associated with Down's, endocardial cushion defect
right arch with mirror branching
associated with TOF, and Truncus the left subclavian arises from the front of the arch in right arch with aberrant left subclavian the subclavian artery is the last branch
chiari I
association with tonsillar herniation, klippel-fleil (Congenital fusion of the cervical spine), and of course syringomyelia.
astrocytoma vs ependymoma
astrocytoma is most common neoplasm in kids, low t1, high t 2 , hetero enhancement ependymoma is most common neoplasm in adults, low t1 hight 2 , homogeneous enhancement
biceps tendon rupture most commonly occurs where
at its origin, in the intra-articular supra glenoid tubercle region
Achondroplasia
autosomal dominant, horizontal acetabular roofs, toombstone iliac bones, short femurs (rhizomelia-short proximal long bones), narrowing of the descending vertebral Pedicles, wedged shaped vertebra. Can get hydrocephalus by narrowing of the foramen magnum (leading to a communicating hydrocephalus).
Popliteus
back of knee Origin lateral femoral condyle Insertion posterior medial tibia
Compton scatter
bad predominant interaction in dx energey range above 100kev doesn't depend on Z , 1/E does depend on density of material domiant force contributing to scatter/fog.
kvp and mas in regards to radiation
beam intensity = (kvp)^2 mA has no role in avg energy or peak energy of the spectrum mA is the number of electrons per second (mAS)
Chondroblastoma
benign bone tumor, <20; epiphyseal/metaphyseal, T2 dark (unlike the other AIG C) Prefers femoral greater trochanter(apophysis which is epiphysis equivalent) to the femoral epiphysis. NOT T2 BRIGHT, unlike other chondroid lesions.
Intraductal papilloma
benign tumor of lactiferous duct/sinus, MCC bloody nipple discharge in <50. Ultrasound will show a round filling defect in dilated duct, with internal Doppler vasularity, intraductal debri will not have vascularity.
lateral resolution
best at focal zone, changes with depth , best with anrrow pulse beam width, best with higher frequency (longer fresnel), best with higher scan line density. larger diameter transducers have longer focal zones.
Yttrium-90
beta, 175 and 185 KeV, 64hr, 20-40 um particle sizes, used for liver tumors before giving, do 99Tc-MAA hepatic arterial injection to make sure less than 10% lung shunt, if not can get radiation pneumonitis.
changes status post vascectomy
bilaterally (usually bl) enlarged edidydimis , likely 2/2 rupture of the vas deferens. theres no increased blood flow to suggest epidimytis or lymphoma.
types of placenta
bilobed placenta, increased risk of vasa previa succenturiate lobe- one or more small accessory lobes- assoc. with vasa previa circumvallate placenta- rolled placental edges, with smaller chorinoic plate (increased risk for placenta abruption and IUGR) .
erheim chester disease
bl perirenal soft tissues, bl metadiaphyseal sclerotic lesions, and interlobular septal thickening in the lungs.
gallium 67 and technetium mdp scans
both can be done to assess for inflammation. in cases where the gallium is discoordant or higher than an area on the mdp scan, its infection. in cases where the mdp is higher than the ga-67 its degenerative in nature. if they are both concordant then its an equivocal study.
cppd vs hemochromatosis
both can lead to calcium pyrophosphate deposition leading to chondrocalcinosis, cpppd favors the index and middle finger, while hemochromatosis favors the 1-4th fingers.
Pineal germinoma
boys, precocious puberty from hCG, mass containing fat & CENTRAL calcs w/ variable enhancement, heterogenous T1/2
Phyllodes tumor
bulky tumor derived from stromal cells; lobulated tumor with cystic spaces containing "leaf-like" extensions often reaching massive size; tx w/ wide excision Most common at 40-60 yo, unlike fibroadenoma which is at 24-40 y/o when it peaks
when has all longitudinal magnetization been recovered
by 4 x T1; 63% has recovered by T1, 87% by 2 x T1, 95% by 3 X T1.
minimal slice thickness is determined in CT how
by detector elements aperture width
How are x rays produced
by the acceleration of electrons from the cathode to the anode - DC (direct current) only, also breahmstraung interactions (breaking radiation) as high energy electrons hit atoms and photons are produced.
Acute svc occlusion
can be 2/2 catheter placement, will result in acute swelling of face, neck, and airway compromise from the edema. You may see retro pharyngeal swelling. Chronic SVC will present with a small vena cava if its occluded, or tumor/lymphadenopathy in its vicinity.
spinal cord herniation
can be due to weakened dural fibers, the spinal cord migrates ventral or dorsal, the narrowing here leads to an upper syringohydromyelia usually.
Nonketotic hyperglycemia
can lead to lethary and drowsiness and seizures of all kinds. can also have syndrome of dystonia and chorea w/ reversible T1 hyperintensity in basal ganglia. can also lead to cerebral edema. Usually t1 first hits putamen, then caudate.
bony growth of the epiphyses
can occur in hemophilia and in juvenile arthritis (occurs in juvenile arthritis bc the chronic synovitis leads to hyperemei, which then stimulates the bones to grow more than usual , since its a child and still can grow), both get widening of the intercondylar notch.
breast feeding and post gad exam
can resume right away.
2 chamber myocardial view
can see global LV function, mitral valve issues. The coronary sinus can be seen behind the LA in this view.
endometrioma cancer risk
can transform to clear cell or endometrioid subtype of cancer, will have high t1, and low t2 swith some t2 shading, however they will have enhancing nodular components as well.
Adrenocortical carcinoma
cancerous tumor originating in the cortex of the adrenal gland Seen in kids <6 or adults in 30-40s, Causes virilization in kids, usually less than 6 y/o Cushings or virilization in adults
thrombolysis for acute limb ischemia
catheter assistent thrombolysis is the first choice, if the patient has no athersoclerotic disease or collaterals, its an acute process, no need for stent or angioplasty (opening up vessel with balloon).
umbilical cord cysts
central is allantoic cyst, peripheral is omphalomesenteric duct cyst. if seen in 2nd or 3rd trimester then they will be associated with trisomy 18 and 13.
Cadasil
cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy Notch gene defect Anterioe temporal lobe invovlement bilaterally is pretty specific.
aliasing or wrap around artifact correction
change phase/frequency encoding direction, increase FOV, use filters for outside field of view, oversample outside field of view.
pediatric tumor with highest association with bone mets
clear cell sarcoma (60-70%), wilms is 2%.
decrease dose in fluoro
closer to II collimate avoid magnification
coarse heterogeneous vs fine pleomorphic calcifications
coarse heterogeneous >0.5mm fine pleomorphic <05.mm
lung mets from rectal cancer
colorectal cancer tends to go to the portal vein, up to the superior rectal region which drains into the IVC via the superior hemorrhoidal. mid and lower rectal regions drain into the portal and iliac veins, so with rectal cancer you can have lung mets without liver mets, unlike colon ca.
jefferson fracture
comminuted fx of c1, if there is separation fo teh lateral masses, then theres indication of transverse ligament injury, and thats unstable, otherwise its not an unstable lesion and can be tx conservatively if not unstable.
Pulsation artifact
commonly associated with fast spin echo; not GRE, DWI or STIR as much.
compton scatter vs PE
compton scatter contributes to image noise PE contributes to image contrast, and determines quantum mottle due to more photons being absorbed and less hitting the receptor.
hydranencephaly
cortical mantle is gone , due to ischemic infarct involving both MCAs, herpes can cause this. still have a flax unlike holoprocencephaly. hydrocephalus you have both the falx and the cortical mantle present
gout
crystal arthropathy, deposition of uric acid crystals in and around the joints. spares the joints space (until late in the disease) juxta-articular erosions away from the joint punched out lytic lesions overhanging edges soft tissue tophi (dark on mri, will enhance)
inherent limitations to PET
crystal thickness (number of detectors) positron range angulation/collinearity scatter
small cell paraneoplastic syndromes
cushing, siadh, lambert-eaton, not hypercalcemia (thats squamous cell) Small cell and Squamous cell lung cancers are both Sentral in location
arthrofibrosis
cyclops lesion, fibrosis at hoffa's fat pad seen usually 16 weeks post op
Cystic adventitial disease
cystic structure containing mucin forms within the popliteal artery adeventitia cysts may spontaneously rupture and recur Young men Tx is surgery
PET QA - Blank scan and normalizations can
daily, use germanium or Cs without cilinder or Ge/Ga with cylinder. if you were diagonal thin line (bad crystal), thick diagonal line (bad detector). normalization scan- monthly , expose detectors to flux of positrons similar to daily.
K-space
data acquisition matrix containing raw image data prior to image processing. The Fourier transform of k-space is the magnetic resonance image Contrast info in the center, spatial resolution in the periphery
how to reduce type 1 chemical shift artifact
decrease FOV, decrease pixel (pixel=fov/matrix), decrease magnetic field strength, or increase receiver band width. Swap pe/fe directions (this artifact occurs in the frequency encoding direction). Use STIR, or other fat suppressing techniques. type 2 chemical shift--> adjust TE, perform spin echo (only occurs in gradient echo, whereas type 1 occurs in gradient and spin echo).
iron overload on cardiac MRI
decreases T2* relaxatio times. <20msec are indicative of significant iron depostion, <10msec are indicative of increased risk for heart failure and arrhythmias. if theres increase in T2* its indicative of improvement.
Esophageal ring
defined concentric, smooth, thin extension of normal esophageal tissue, usually found in distal esophagous, of mucosa. associated with Patterson-Kelly Syndrome (Plummer-Vinson)-iron def anemia, thyroid issues, esophageal and hypopharynx increased cancer risk
Fucntional MRI
depends on inhomogeneity secondary to oxy and deoxyhemoglobin leading to T2*
major determinant of intrinsic spatial resolution
detector face size
Joubert's syndrome
development malformation of the cerebellum, get superior cerebellar peduncles, elongating into the back of the midbrain to look like a molar tooth. vermis is hypoplastic but still there, so no fused horizontal tracts associated with retinal dysplasia (50%) and dysplastic kidneys (30%).
Madelung deformity
developmental abnormality of the wrist- anatomic changes in radius, ulna, and carpal bones, leading to palmar and ulnar wrist subluxation (of the radicarpal joint space); more common in females (esp gymnasts), usually bilateral; early closure of the ulnar sided growth plate of the distal radius. Becomes evident b/t ages 6-13 years, epiphyseal plate changes is the distal radius (ulnar side, and the radial aspect of the radius continue to grow, leading to positive ulnar variance, and the V shaped deformity) and closure of the plate as a result of loading the wrist and forearm in gymnastics; produces a skeletal deformity (carpus wedged b/t radius and ulna); s/s: wrist pain, loss of forearm rotation, palmar subluxation with prominence of radial/ulnar styloids; manage: treat pain, tape wrist or provide brace (prevent end-range extension), typically corrected surgically Leads to ulnocarpal impaction, leading to messed up tfcc and therefore inability to properly grip
First sign of hydrocephalus
dilatation of the temporal horns
Indium 111 oxine leukocytes (WBCs)
distribution: spleen> liver> bone marrow infection scan at 24 hr, but to look for inflammatory bowel disease perform a read also at 4 hrs, bc mucosa can slough off and dissipate by time 24 hrs read comes and give a false spread (higher than actual region of inflammation). No interfering bowel/kidney, and can use w Sulfur Colloid or MDP simult
hVL
doesn't depend on mA does depend on beam filtration does depend on anode material (bigger z bigger avg energy from Brems) does depend on KVP more filtration=higher hvl less filtration = less hvl
electronic magnification in fluoro FPD
dont do geometric mag bc it will end up increasing dose, due to ABC taking over. electronic magnification in FPD is like magnifying on a camera, post image, you can also collimate. this overall leads to less area sampled(and hence less kAP= dose x cross sectional area, and you decrease the cross sectional area). collimation will however increase air karma, bc the entrance dose is going to be less, and the ABC will take over to make up for it.
doses
dose limit to a member of the general public = 1mSv or 100 mrem background dose limit= 3mSv or 300 mrem dose limit to fetus 5msV or 500mrem total effective occupational dose limit for a radiation worker 5= 50 mSev or 5000mrem dose limit for rad worker lens =150mSev or 150000mrem dose limit to radiation workers extremity =500mSv or 50000 mrem
Cyclotron produced radionuclides
due to irradiation of nuclei with chraged particles (alpha particles, protons). produces isotopes that are neutron deficient. thys , they decay by positron emission or electron capture, both will increase neutron count by 1 and decrease proton count by 1. which one of the two processes depends on whether there is 1.022MeV of energy available for the nucleus. if there energy is available it will undergo positron emission. positron emission:C-11, N-13, O-15, F-18. electron capture: Co-57, Ga-67, In-111, Tl-201, and I-123.
india ink artifact
due to type ii artifact, or phase cancellation artifact. This occurs in all directions (phase and freq) bc its in any direction within the slice that contains water and fat. seen only in GRE not SE. Type I is seen on both GRE and SE. this decreases with increasing gradient strenght.
flare phenomenon
early after effective treatment with chemo scan uptake in mets can increase as the xray is getting more sclerotic and the patient is improving, can last up to 6 months, so do 6 month follow up study, it usually indicates partial response. If on 6 month scan theres more bone marrow uptake then its usually indicative of disease progression.
effective dose
effects of radiation on tissue types, accounting for organ specific radiation sensitivity.
canavan's
elevated NAA on SPECT
Congenital adrenal rests
embryologic remnants of adrenal tissue trapped in the testes typically seen in newborns with congenital adrenal hyperplasia (enlarged adrenal glands with cribiform appearance), check lab work to prevent orchiectomy Intratesticular masses, usually eccentric.
chiari iii
encephalocele in the occipital region
most predictive criteria of chest involvement in breast cancer
enhancement of the pectoralis muscle
most common ovarian neoplasm
epithelial tumors , of which serous cystadenoma is the most common. mucinous cystadenoma tends to be multilocular with internal gelatinous material serous cystadenoma tends to be unilocular with serous material
enchondroma vs low grade chondrosarcoma
factors favoring chondrosarcoma: pain cortical destruction, scalloping >2/3 of cortex >5cm in size changing matrix
anencephaly
failure of closure of neural tube in the brain, leading to high AFP, and polyhydramnios(hard to swallow without a brain)
Persistent hyperplastic primary vitreous
failure of the embryonic ocular blood supply to regress can lead to retinal detachment will have a small eye with increased density of the vitreous martini glass sign,thin v shaped dark on t2 bright background.
MUGA
false low EF= when you screw up LAO and can cause overlap of LV with RA/RV or great vessels. false high EF=wrong background ROI (over the spleen) will cause over-subtraction of background and elevate the EF.
arrhythmogenic right ventricular arrhythmia
fatty replacement is actually note included as a major criteria for diagnosis radiologically, its RV dilatation RV dysfunction, and RV aneurysm
arrhythmogenic right ventricular dysplasia
fatty replacement of the RV free wall due to abnormal structural proteins in between the myocytes; may also involve the LV can be a cause for intractable arrhythmias and sudden death autosomal dominant disorder with variable penetrance AICD is tx
radiation induced sterility numbers
females (young) 10Gy older females 2Gy, , if no age given say 6Gy males temporary- 0.15-0.25Gy males permanent- 5 Gy
birads 3 lesions
fibroadenoma, focal asymmetry(seen in two projection) , grouped round calcs; also note this is only for baseline screeners, you can't have this on a follow up pt with this new findings (those need further workup) developing asymmetry-> wasnt there before, now is....not birds 3!
image contrast and latitude
film screen has better contrast, but digital film has better latitude (you can window more) widening window results in decreased contrast on digital radiography
high grade atherosclerosis of the renal arteries
first choice is medical treatment above thrombolysis and stenting according to CORAL trial .
order of vascular compromise in ovarian torsion
first the lymphatic (ovary enlarges), then the venous, and finally the arterial (why arterial is not reliable in ovarian torsion).
av graft vs av fitula
fistula=needs 3-4 months to mature, less risk of infection, neointimal hyperplasia and lasts longer graft-takes 2 weeks to use, easier to declot, but increased risk of clotting (neointimal hyperplasia), infection. <600cc/min for graft=slow flow <500 cc/min for fistula=slow flow; first six months of graft stenosis tends to be at the arterial side, after 6 months, its tends to be at the venous side. first 2-3 times you do angioplasty, after stent bc arm moves alot.
Loozer zone
focal horizontal (perpendicular to cortex) area of noncalcified osteoid deposition, within the MEDIAL SUBTROCHANTERIC REGION, INFERIOR TO THE LESSER TROCHANTER
MRI descriptors
foci<5mm mass>5mm non-mass enhancement
half value layer for lead
for 511kEV = 4mm for 140kEV=0.25mm
KVP in fluoro
for iodine angio kv =70, hit idoine k edge of 33. for bariun, kv>100 , chosen to Max out penetration.
radiochemical impurity
fraction of radioactivity in a dose that is in the undesired chemical form, i.e. free Tc-99m and insoluble colloids in a Tc-99m MDP dose for example. Use chromatography to detect this. , >95% of compound must be in desired form. chemical impurity is how much aluminum is in eluate (<10microg/ml), uses colorimetry test. radionuclide impurity is how much Mo is in Tc99 for example (0.15microg/1mCi). This uses a dose calibrator.
split peroneus brevis
from recurrent inversion injuries, looks like boomerang with medial vertical line of split.
alexander's leukodystrophy
frontal lobe symmetric
osteochondritis dissecans
fx involving the cartilage and underlying bone, most commonly about the lateral aspect of the medial femoral condyle.
pre PET
glucose <200 no exercise 4-6 hrs prior no food drink 4-6 hrs prior
pulsed fluoro
good for moving pts, sharper images with less motion blur can reduces dose when frame rate is below 30frames/sec (not 1:1 , 50% reduction in pulse rate= 30% reduction in dose).
gradient MRI sequences and tempersture
gradient images lower the specific absorption rate (less heating).
bernuolis equation
gradient= 4 (Max Velocity in m/s)^2 Vmax in aorta is 300mm/s= 3m/sec (3^2) x 4= 36mmHg is the gradient accross the aorta.
spatial resolution
greater pixel density, pixels per area, the better the spatial resolution bigger the matrix, more pixels inside pixel pitch (distance btw pixels)= the large the pitch the worse the spatial resolution.
Griffith's point vs. Sudeck's point
griffith is splenic watershed, btw the superior left colic artery (IMA) and the artery of Drummond (SMA), this is the most common site of ischemic infarct. sudeck's point is between the IMA and the superior rectal artery .
the serum concentration of tPA
half life of 5mins; after around 25 mins there will be no discernible concentration in blood.
critical organ in RBC bleeding scan
heart
axial vs helical ct scan
helical the beam moves 360 continuously, allows faster scan time, z axis allows for overlap which allows reconstruction in coronal and sagittal, axial ct scan reproduces stair step artifact, which is corrected by using helical , using thinner slices and collimating more
what liver lesion can be seen with rbc study in liver
hemangioma (>95%)
sinus tarsi syndrome
hemorrhage/inflammation in this synovial recess between the lateral talus and the calcaneous, related to flat foot progression, also to other shit. Has proprioception and you mess that up and are predisposed to plantar fasciitis.
effect of mAS and KVP on focal spot
high mAs gives wider spot higher kvp gives narrower spot
west nile virus
high t2 in basal ganglia and thalamus
PIOPED II
high: two large mismatched segments intermed: one lrg mismatch or triple match in lower lobe low: large/mod matched, absent lung, small segment very low: nonseg lesions, stripe sign (2/2 pleural effusion), one to three small segmental defects, single triple matched defect in the upper/middle lung zone, perfusion defect smaller than the corresponding chest radiograph abnormality.
electronic magnification in fluoro
hit only 1/2 on input phosphor on II, then only 1/4 will leave the output phosphor. this leads to better spatial resolution but overall decrease in dose makes ABC increase overall dose. what improves spatial resolution in fluoro? electronic magnification
absorbed dose
how much xray energy gets into the tissue per kg of tissue, measured in Gy
hsv encephalitis
hsv-1 in adults hsv 2 in kids/children
HAGL
humeral avulsion glenohumeral ligament, avulsion of inferior glenohumeral ligament, looks like a J, the humeral side gets hit. This is the same ligament that on the glenoid side gets displaced medially in ALPSA with intact covering periosteum.
blood stages
hyperacute (oxyhemoglobin), acute 1-3 days (deoxyhemoglobin intracellular), early subacute >3 days (methemoglobin intracellular), late subacute (methemoglobin, extracellular), chronic >14 days (ferritin, hemosiderin).
Heiner syndrome
hypersensitivity pulmonary hemosiderosis (pulmonary hemorrhage in 4-29 month infants due to milk protein allergy)
palpable mass in a male breast
if >25 yo--> diagnostic mammo if <25 yo-->ultrasound
flow in endometrium after birth
if bchg still elevated think retained products, if bhcg going down think AVF/AVM.
IVC filter clots
if clot is more than 1cm in the filter, you need to lyse it before you can remove the filter, or the filter stays in.
When to treat renal artery aneurysm
if more than 2cm, or patient is symptomatic, also pregnancy.
free technetium vs tc MAA from r-l shunt
if you see activity in stomach its due to free tech, activity within the kidneys and thryoid may be seen due to either free pertechnetate or r-l cardiac shnt, when seen, planar images of the brain should be acquired to differentiate between the two.
Uptake on bone scan
if you see lots of uptake in lungs, liver, stomach, thyroid, periarticular regions, think of hypercalcmeia from chronic renal failure , on bone scan. Mets wouldn't do this, neither would free pertechnetate (it'll be in thyroid and stomach, but not lungs or liver). If you see lots of uptake in the muscles, with some in the bones, think of rhabdomyolysis.
highest radiation dose in IR in terms of operator positionoing
if youre next to the patient, and radiation source is below youll get most , but youll get even more if the source is obligue to patient and closer to you , as youll need more juice to penetrate more patient tissue, and will therefore get more scatter from patienet than if you were perpendicular to source only.
ileal atresia vs meconium difference on barium enema
ileal atresia will have complete canal closure, so contrast wont fill the proximally dilated small bowel, while in meconium ileus it will
diffuse idiopathic neuroendocrine cell hyperplasia
ill defined air trapping, throughout both longs, no bronchiectasis, or honeycombing or architectural distortion. Multiple pulmonary nodules are seen as well. Its a constrictive bronchiolitis.
luminance and illuminance
illuminanse is the ambient light intensity , should not exceed 50 lux. luminance is the amount of light detected by the human eye or simply brightness of the monitor. for mammo 3000 candela/m2, and for radiographs 1500 candela/m2.
octeotride scan
images are sampled at 6 and 24 hrs, respectively, look for high uptake in the spleen and the kidneys.
medications that should be stopped prior to I-123MIBG for neuroendocrine tumors
imipramine, TCAs, insulin.
thicker photostimulator phosphor
improved detective quantum efficiency bc xrays are more efficiently captured and recorded if it was thinner more high energy xrays would go through, it wont stop as many to be recoeded; but increased scatter inside a thicker PSP so loss of resolution aka loss of modulation transfer function, overall improved SNR (bc you capture more xrays). Direct detector has the best detective quantum efficiency
PET time of flight
improved spatial resolution and image contrast
primary factors influencing image contrast
in digital is the LUT look up table which assigns corresponding grayscale based on input densities. in plain film primary factors is kVP.
geometric vs electronic magnification an KAP
in geometric KAP doesn't change. Geometric will however increase air karma bc skin is now closer to source. in electronic magnification, you collimate then expand that smaller area on the screen, so you may increase kvp or mA through ABC, but you sample a smaller area so kAP doesn't change.
star artifact
in i-131, from using a low to medium collimator for high gamma I-131, so energy penetrates septa.
TR and TE and SNR
increaesing TR and decreasing TE (Like a proton density weighter image) makes for better SNR. long TR you are giving time for full recovery, this is why long TR improves SNR.
Increasing the flip angle in GRE will do what to T1 weighting?
increase T1 influence Increasing TE in GRE, increases the T2 *, just like increasing the TE will increase the T2 in spin echo images.
truncation artifact correction
increase matrix size (fov/matrix=voxel), and use of smoothing filters
How to decrease beam hardening artifact
increase the kvP. beam hardening decreases the number of low energy photons in a multifocal spectrum. You have net loss of protons so net output is decreased
how to fix aliasing
increase the pulse repetition frequency, and decrease the incident angle (decreases the measured Doppler shift and hence reducing aliasing.) Also decrease the pulse period (1/PRF). Decreasing ultrasound frequency also improves aliasing.
kvp and dose in fluoro and CT
increased KVP in fluoro reduced dose (more penetrates skin) increased kVp in CT increased dose bc you're rotating-spreading your skin dose.
reduction mammoplasty
increased density along the inferior margins of both breast
Compton scatter probability
increased probability with increased density of matter. increases in matter with abundant hydrogen. increase with decreased photon energy, inversely proportional to photon energy- higher energy photons would go directly to the nucleus. More matter more scatter (bigger patients get more scatter) Higher FOV, greater Compton scatter
Nuchal lucency
increased thickness in the nuchal fold area in the back of the neck associated with trisomy 21 At 9-12 weeks
ultrasound transmit power
increases amplitude of pulse, so increases SNR, penetrance, and image brightness, side effect is greater bioeffects.
collimation
increases image contrast, improves SNR, and decreases noise.
scatter
increases with: higher kvp technique (more Compton scatter dominates) larger field of view thick parts (or people)
magnification in general radiology vs mammo
increasing geometric magnification will decrease spatial resolution bc of increased blur. in mammo bc of small focal spot , geometric magnification increases spatial resolution . this all has to do with the intrinsic receptor resolution / focal spot size. can try to collimate to fix geometric mag in normal radiography. less minification (smaller fov actually created by more kvp to make focal spot thinner) = magnification = less brightness gain compared to reg fluoro with bigger normal focal spot.
Nasolacrimal duct drains where
inferior meatus Frontal, anterior ehtmoid and maxillary drain into the middle meatus, posterior ethmoid and sphenoid drain into the superior meatus.
First branch of the SMA
inferior pancreaticoduodenal
dypiridamole
inhibits breakdown of adenosine
First pass radionuclide angiography study
inject in the right ij, or antecubital (has to be close so you don't get fractionalized bonus), then take 20-30 sec/frame to see counts, it's essentially done to see right ventricular function (RF). Patient 20-30 degrees RAO to separate right atrium from right ventricle. MUGSA scan uses equilibrium, more radiation, tagged RBI's, takes more time, used to assess LV EF.
electronic magnification in fluoroscopy
input phosphor diameter/output phosphor diameter. when decreasing magnification, image input phosphor diameter is decreased and image brightness is decreased , but the automatic exposure rate control maintains constant signal-to-noise-ratio and thus image brightness.
percutaneous nephrolithotripsy
instead of going for the posterolateral lower pole (like normal PCN) you aim for the superior or middle pole (easier to retract the stone)
relative intensities in ultrasound modes
intensity-power/area B mode-regular ultrasound to scan abdomen m- mode -focused on a fetal heart to assess hr, more concentrated, smaller beam (therefore greater beam intensity) Doppler- uses an even smaller beam (greatest beam intensity therefore) to assess small vessels for color shift velocities, spectral doppler (like arterial ultraosund) is even more intense than color doppler or power dopler bc you remain static looking at vessel with a small intense beam, with power doppler and color doppler you move a little the probe so less focal intensity. spectral power doppler can be made even worse with high pulse repetition frequency (high limit on frequency scale aka higher nyquist freq).
MRI SPECT
intermediate TE to get lactate/lipid peaks to differentiate choline =high cell turnover (tumor, inflammation, abscess) NAA= cell viability (decreases with tumor, abscess, radiation) Lactate = increased in tumor, radiation choline is high in high grade tumors and low in radiation necrosis. alanine peak=meningioma myonositol is high in alzheimer's
cardiac fibroma
intramural, rather than intracavitary (myxoma) mass , most commonly in kids (second most common after rhabdomyoma), will be like fibrous tissue, dark on MRI. Assocaited with basal nevus cell syndrome (Ghorlin syndrome).
nasopharynx masses
inverted papilloma has mass like cerebreform enhancement, and remodels bone sinonasal polyposis is polyposis of the mucosa, usually starts at the sinus walls and does not demonstrate mass like enhancement. fungal sinusitis demonstrates heterogeneous appearance on MRI and usually has rind like enhancement. SCC invades and ****s shit up
# of frequency encoding steps
is the number of times you sample the echo, the number of times you repeat x TR.
Image internsifier (fluoroscopy)
its a vacuum chamber. Input has a CeI phosphor that converts x rays into light, then there is a photocathode that converts light into electrons, the electrons travel in vaccum until they hit the output screen phosphur which converts the electrons into light, and the light leaves via a glass window. you accelerate electrons via the photocathode (flux gain), and then you aim at a smaller output screen (called minification gain). brightness in II= flux gain x minification gain. CCD camera picks up the exiting light out.
Osteochondritis Dissecans (OCD)
joint condition in which bone underneath the cartilage of a joint dies due to lack of blood flow . Stage 2 is stable on probing (picking at it ), stage 3 is unstable , stage 4 is out Can lead to secondary OA See line of high T2 signal underneath the cortex , as it is separated from normal cortex
jones fx vs avulsion fx
jones fracture extends to the intermetatarsal joint, avulsion fx extends to the tarsometatarsal joint (closer).
Pineoblastoma
kids, highly invasive, like a PNET in the pineal gland, a/w retinoblastoma, heterogenous, vivid enhancement, PERIPHERAL calcs
Choroid plexus carcinoma
kids, lateral ventricle / trigone, a/w Li-Fraumeni syndrome (bad p53), CSF spread Not seen in elderly is important, likely something else, like mets.
Air Kerma
kinetic energy released per unit mass of air Significantly increased in DSA compared to digital fluoroscopy
cardiac nuclear medicine and left bundle branch block
known LBBB will make ECG stress testing non-diagnostic. The septum can't relax, and so you get a false positive in the anteroseptal region on cardiac nucs. Use regadenoson (adenosine agonist with less pulmonary effects). Dobutamine makes this defect worse, so you use regadenoson , adenosine or dipyridamole better).
Albright hereditary osteodystrophy
lack of responsiveness to parathyroid hormone results in: short stature, characteristically shortened 4th and 5th metacarpals, rounded faces, and mild mental retardation low calcium, high phosphorus, and high parathyroid hormone.
how to fix truncation artifact
larger matrix and use of smoothing filters
CR trivia
laser spot size, smaller the better the spatial resolution thicker phosphor plate the more light scatter more sampling freq smaller pixel pitch which improves spatial resolution smaller plate size for given field of view improves spatial resolution
latent vs active errors
latent errors are design flaws that have effect on pt, not directly related to pt contact. active errors are directly affecting patients.
Segund fracture
lateral proximal tibia, indicative of ACL injury Reverse Segund , medial proximal tibia, indicative of PCL injury
sinus related ASD
like the ones associated with anomalous pulmonary venous return (like Scimitar) cannot be closed with an Amplatzer, bc you don't have rind to attach device.
If you see permanent accumulation of tracer in stomach on a tagged RBC study
likely free Tc pertechnetate should look at the thyroid and salivary glands, to see accumulation of tracer there as well can be 2/2 labelling autologous RBCs in vivo. tagged RBC study can be differentiated from sulfur colloid bc sulfur colloid demonstrates no activity in the blood pool. Free tech pertechnetate will also accumulate in kidney and bladder. RBC study with 90-120 min delay, likely looking for hemangioma (late enhancement), false negatives for hemangiomas usually involve small lesions, lesions >2cm seen almosst 100%.
hsv encephalitis
limbic system, most sensitive test is restricted diffusion -differential includes limbic encephalitis (non small cell paraneoplastic syndrome, q will say HSV negative)
spatial resolution with flat panel detectors
limited to the DELs, smaller detector elements the better the spatial resolution.
Collimation
limits pt exposure and reduces scatter. decreases field size which decreases scatter(noise). it increases quantum mottle (less photons overall) decreases dose (less photons) machine will increase mAs when collimating to make up.
moire artifact
lines and curves on the outside of images, 2/2 aliasing and overlapping images, its seen in gradient echo images. Seen when using body coils.
Hepatic artery thrombosis post liver transplant
liver infarction is uncommn because of dual blood supply Does cause primary bile duct ischemia as the hepatic artery is the sole provider of blood to the bile ducts in post transplant patients.
best way to differentiate attenuation defect from true infarct on cardiac nukes?
look at gated images, normal wall motion if its attenuation. The infarct will show akinetic walls.
mesonephric nephroma
looks just like Wilm's but in a neonate.
osteofibrosus dysplasia
looks like an NOF, associated with anterior tibial bowing , centered in the anterior tibia (not on the cortical side like NOF).
fibrothecoma
low T1/T2 ovarian lesions, assoc. with Meig's syndrome ultrasound demonstrates profuse posterior shadowin (unlike endometrioma).
rheumatoid pulmonary findings
lower lobe predominant, can lead to UIP, NSIP pattern, has cavitary nodules, bronchiectasis, usually unilateral pleural effusions. Does not have hilar adenopathy usually
lymphangitic carcinomatosis vs sarcoidosis
lymphangitic carcinomatosis will present similar to sarcoidosis with perilymphatic , subpleural nodules, etc, but unlike lymphangitic carcinomatosis , sarcoidosis can present with fibrosis/architectural distortion, its how you tell them apart.
particle size
lymphoscintigraphy :<0.2micron (<200nm) V/Q: 10-100 microns (10,000-100,000nm) liver/spleen: unfiltered.
pathologic fracture risk
lytic lesions >3cm >50% cortex
effective mAs
mAs/pitch
macroscopic fat vs microscopic fat
macroscopic fat, just like one in ovarian teratomas will not drop on in and out of phase imaging, microscopic fat will not drop on in and out of phase imaging bc it contains fat and water in the same voxel for MRI.
Heel effect
made better: larger anode angle increased source to image receiver distance (more central band, the outer bands spread out) smaller image receiver (to also only get the more uniform central bands).
adenoid cystic
malignant tumor of the glands, likes perineural spread
Detective Quantum Efficiency (DQE)
measurement of how efficiently a system converts an x-ray input signal into a useful output image Proportional to MTF (modulation transfer function) Inversely relate to spatial resolution, bc you'll need more dose (photon density) to see fine details. High DQE (low dose), low DQE (high dose) THE BETTER YOUR DQE THE LESS RADIATION YOU NEED TO MAINTAIN YOUR SIGNAL.
when is stereotactic biopsy suboptimal?
medial posterior breast and superficial (for superficial ultrasound approach is best)
MQSA Mammo
medical audit and outcome analysis yearly-per USFDA -cancer detection rate >2.5/1000 -3 months training in residency -recall rate 5-12% - lay report within 30 days -consumer complaint mechanism must be est in mammo -required resoution in anode to cathode direction is 13lp/mm, 11 lp/mm in left right direction. -pass image quality , 4 fibers, 3 microcalc clusters, 3 masses plus acceptable artifact -dose phantom is 50% glandularity, 4.2cm thick, dose less then 3mGy per image (+grid). -digital systems typically use higher beam quality; digital mammo doesnt use fixed dose (screen film). appropriate target range for medical audit: recall rate 4-7% cancer/1000 screened 3-8
Collimators
medium energy collimators measure energy up to 400kEV Low energy collimators measure up to 170 kEV. I-131 uses high collimators
Contrast to Noise Ratio (CNR)
method of describing the contrast resolution compared with the amount of noise apparent in a digital image, the contrast is the difference in intensity between lung and bone interfaces for example.
brightness gain
minification gain x flux gain in fluroro . minification through output phosphor and flux through e going from photodiode to output phosphor. older II require more dose for this light gain. once it reaches 50% of production must replace.
T sign in twins means
monochorionic pregnancy - absence of twin peak sign
Twin-twin transfusion syndrome
monochorionic twin pregnancy with single placenta (monochorionic monoamniotic), can be mono or diamniotic, and arteriovenous shunt within the placenta. true twin twin transfusion occurs only in monochorionic, diamniotic, the donor twin gets oligohydramnios and the amniotic cavity compresses it against the sac. T sign(thin membrane btw fetuses) indicative of monochorionic monoamniotic Lambda sign (thick membrane) indicative of diamniotic . reversal flow in umbilical vein
Noise in ct
more photons less relative noise, increase mAS to get less noise. takes 4x the photons to double the signal yo noise ratio bc of math. increase mas from 2--> 4 , noise drops by (square root of 2)
reportable event
more than 20% dose or wrong patient, or wrong med, wrong route, and more than 50mSv to total body, more than 500mSv to organ.
restrictive cardiomyopathy
most common cause is amyloid, which will show diffuse subendocardial enhancement difficult to suppress myocardium, long TI> 200msec , around 350msec is classic for amyloid
posterior tibial tendon
most common cause of flat feet, usually chronic from tears at the medial malleolus, if acute its usually at the navicular where it inserts. accessory navicular can lead to pain of the distal posterior tibial tendon. then spring ligament gets jacked up , and you end up with flat foot, and then plantar fasciitis. sinus tarsi also gets jacked. then you get hindfoot valgus (inward feet with toes pointing out, the hindfoot valgus angle is also more than 180, hindfoot pointing out)
mets to heart
most common is bronchogenic carcinoma (lung), highest percentage per cancer is melanoma.
ependymoma vs astrocytoma
most common is ependymoma, tend to bleed (high t1), tend to be centric not eccentric like astrocytoma or hemangioblastomas. The ependymomas also have a dark rim usually as well. astrocytomas are more common in kids.
pleomorphic adenoma
most common major and minor salivary gland tumor, most are benign
mucoepidermoid carcinoma
most common malignant tumor of the major and minor salivary glands, associated with radiation.
Metachromatic leukodystrophy
most common of the leukodystrophies central and periventricular subcortical in distribution tigroid-black lines intermixed with the high t2 white matter signal
discoid meniscus
most common on the lateral meniscus, tx is saucerization if symptomatic, conservative therapy is usually for kids.
rheumatic heart disease
most commonly involves the mitral and aortic valves, anytime there is multivalve disease, think rheumatic fever.
proximal esophageal rupture
most commonly on the right most common rupture of the distal esophagus is on the left side (present with left sided pleural effusion, but first findings is pmeumomediastinum)
quadricuspid aortic valve
most likely results in aortic insufficiency seen also with truncus arteriosus
Intensifying screens
mounted in the cassette singly or in pairs, these screens glow with visible light when struck by radiation and expose the film contained in the cassette Decrease radiation by decreasing the amount of mA required for film Thicker screens require less strong energy Faster screen films require lower air kerma
Peutz-Jeghers syndrome
mucosal pigmentation; hamartomatous polyps in the small bowel Associated in males with Sertoli cell tumors (bilaterally)
localizing lesion only seen on MLO
muffins rise, lead sinks if its up on the ML view (muffins rise), so it'll be Medial on the CC if its down on the ML view (lead sinks), so it'll be Lateral on the CC.
multicentric vs multifocal breast cancer
multicentric is in multiple quadrants of the breast.
carneys complex
multiple myxomas (including cardiac and extracardiac), endocrine neoplasm (pituitary adenoma), and skin hyperpigmentation. AD.
size of a diverticular abscess to drain
must be bigger than 2cm size of perinephric abscess to put drain, >3cm.
adenoma vs myelolipoma on fat suppression
myelolipoma has macroscopic fat so it suppresses on fat suppressed images it contains extracellular fat; adenoma contains intracellular fat and will suppress on in/out phase (myelolipoma wont but will show india ink around lesion compared to rest of adrenal gland) the longer the TE, the more the T2*, so the less youll see signal drop from fat, so you want out of phase at 2.2, and in phase at 4.4, not inphase at 6.6 (T2* takes over). same principle for hemochromatosis.
Perfusion and PET studies for myocardium
myocardial PET studies should always be interpreted with perfusion studies. to prime the heart, gives a glucose load (with insulin sometimes) so that it goes from fatty acids to glucose, then assess the area of diminished perfusion on the PET (only), if there's a mismatch, i.e. the PET uptakes that area then its likely hibernating myocardium.
window width
narrow (decreased) window width increases contrast wider (increased ) window width decreases contrast the center point of the level is going to determine the brightness. window level determines brightness level up (higher pixel value) =looking at dark stuff (lung) level down (lower pixel value) =looking at bright stuff like bones.
pseudo aneurysm
neck should be less than 1cm, and size of the pseudo aneurysm more than 2cm to use thrombin 05.-1ml, if neck is bigger than 1cm you may need surgery. When you inject the thrombin the needle should be placed in the apex of the cavity, where incoming blood enters. pseudoaneurysm after 30 days hard to decompress and tend not to respond to thrombin therapy.
meningocele vs myelomeningocele
neural tissue is not present in the extruded sac in meningocele.
rhombencephalosynapsis
no vermis, fused cerebellar horizontal tracts on axial imaging
abandoned leads compatible with mri?
no, should not do mri with abandoned leads
noise and distance
noise will increase as the distance btw the tube and detector increase, with increase described by inverse square law.
cervical length
normal 3cm risk of preterm is inversely proportional to cervical length. <2.5cm on or before 24 weeks is concerning.
gallium scan and kidneys
normal to have bilateral uptake at around 24 hrs , abnormal at 48-72 hours, usually indicative of acute interstitial nephritis.
cortical desmoid
not a desmoid, in the posterior epicondyle of the distal femur, usually a tug lesion from medial gastrocenemius, and adductur magnus. it will enhance.
Partial k space acquisition
not all k-space lines are actually acquired missing lines are calculated based on symmetry properties of k-space this assumption reproduces both signal and noise if the line is acquired rather than assumed, noise is different because of its random nature this decreases scan time but decreases SNR SNR= voxel volume X (square root of scan time/receiver bandwidth) , bigger voxel bigger SNR, bigger receiver bandwidth worse SNR. More scan time more SNR.
CO2 contrast
not indicated in coronary or cerebral arteries due to risk of infarction.
nuchal thickness vs nuchal translucency
nuchal thickness >5mm (96% specific for Down, >6mm 99% specific). Measured in 18-21 weeks (second trimester) Nuchal translucency is nonspecific and its measured in the first trimester, 11-14 weeks.
juvenile idiopathic arthritis
occurs before 16 y/o carpals are jacked premature fusion of growth plates serology is often negative enlargement of the epiphyses, widened intercondylar notch, similar to hemophilia epiphyseal overgrowth
nonrotation
occurs when the midgut rotate sonly 180degrees, resulting in small bowel on right, and cecum/colon on the left. usualy asymptomatic .
Aliasing artifact (wrap around artifact)
occurs when tissue outside the Field of View is undersampled, causing a misregistration of anatomical location, in the phase direction, but on the opposite side of the anatomical location, also known as wrap-around artifact, LIKE IF YOU MISS THE BOTTOM OF THE CHEST THEN THAT PART WILL SHOW UP ANTERIORLY The artifact tells you the phase direction bc it follows the phase direction. -Fixed by: A) oversample the data in the frequency encoding direction B) switch phase and frequency encoding direction c) increase FOV (decreases spatial resolution, but improves SNR) d) surface coils e) sat bands-eliminating signal from outside the FOV . Occurs during Fourier transformation (its the fourier thats confused by the data).
Aliasing artifact
occurs when tissue outside the Field of View is undersampled, causing a misregistration of anatomical location, in the phase direction, but on the opposite side of the anatomical location, also known as wrap-around artifact. can occur in the frequency and phase encoding direction, however it can be removed on freq direction with elimination of said samples or acquiring more samples, with phase direction you'd have to increase the phase samples (increasing image time). -it arises during the Fourier transformation (its the fourier that's confused by data outside the FOV).
Pineocytoma
old people, well-circumscribed, non-invasive, solid & enhancing, PERIPHERAL calcs
peribiliary cysts vs caroli's
on MRCP, peribiliary cysts look like sidebranch IPMNs , with dilated peribiliary dilatation, caroli's is dilatation of the intrahepatic ducts themselves (Todali type 5) peribiliary cysts are a benign sequela of biliary cirrhosis.
renovascular hypertension
once captopril is given, will cause decrease in GFR. dtpa depends on gfr, so the post captopril wont have as high of an upstroke and it will just retain. the mag3 will show a slightly delayed upstroke, but its dependent on tubular extraction, however due to decrease gfr, this tubular accumulated agent will not demonstrate washout. artifactual causes of false positive captopril renogram include dehydration, captopril induced hypotension, and calcium channel blockers
warthin's tumor
only in parotid gland, unlike the adenoid cystic tumors which can be in any of the glands. -t2 bright, cystic -only one of gland tumors to take up pertechnetate
Binning
only seen in FPD improves SNR, decreases dose needed, and decreases spatial resolution
pincushion artifact
only seen in II due to geometry of chamber, resulting in lines in middle of screen appearing closer than lines on the periphery 2/2 internal geometry of the II, the periphery of the image may differ from the center, truly straight lines look curved on the periphery
colloid and mucinous breast cancer
only things that are malignant on breast MRI and T2 bright, rest of T2 bright things are benign.
schizencephaly
opening covered by grey matter associations: optic nerve hypoplasia absent septum pellucidum
stapes attaches to what window
oval window, erosion here leads to otosclerosis (should be otospongiosis really then).
tarsal tunnel syndrome
pain in the distribution of the tibial nerve (first 3 toes) from compression in tarsal tunnel .
Median arcuate ligament syndrome
partial or complete compression of the celiac artery origin by the arcuate ligament of the diaphragm Upon expiration (not inspiration), the ligament intermittently compresses the celiac artery as it slides over it and pulls the organs up. Can lead to dilatation and pseudoanuerysm of the pancreaticoduodenal arcades, and will see reflux from SMA run into the hepatic artery.
who gets screened for nephrogenic systemic fibrosis
patients >60, single kidney, renal malignancy hx, HTN, diabetes.
ct geometric efficiency
percent of the beam that hits the detectors, cone beam is used in multidetector CT. geometric eff. increases with # rows, greater real estate to capture them.
Unroofed coronary sinus associated with _______
persistent left SVC
Pet vs spect collimation
pet uses electronic collimation, whereas spect uses lead septa to block noise, this makes pet have more counts. Both gamma cameras and PET should have their uniformity checked daily
Phyllodes vs fibroadenoma
phyllodes can look very similar to a fibroadenoma, with the exception that it will contain internal color flow. if an fibroadenoma grows by 20% in 6 months, biopsy it. phyllodes are excised, wide local excision, 10% can spread hematogenously. fibroadenomas occur in 20-40 yo, phyllodes in 40-60 yo
plantar fasciitis vs plantar fibromatosis
plantar fasciitis is (>4mm thick) with increased t2 signal near insertion at the heel. plantar fibromatosis is nodular thickening of the plantar fascia, usually distally.
Caplan syndrome
pneumoconiosis + rheumatoid nodules in lungs, so its upper lobe predominant, regular rheumatoid lung is lower lobe predominant nodules..
post lumpectomy and radiation changes
post procedure enhancement should subside at around 10-18 months. Enhancement at postlumpectomy site more than 18 months prior is malignancy.
jaccoud arthropathy
post rheumatic fever, looks just like lupus, ulnar deviation of phalanges , that get better on ap view against a surface.
metaphyseal corner fracture
posteromedial corner, meniscal appearing density over the metaphysis, due to sheering forces, swinging the knee back and forth (not from direct trauma) which is what makes it pretty specific for child trauma.
power and axial resolution
power increases beam width, for axial resolution you want a narrow beam , power makes it worse, spatial pulse length is what determines axial resolution. higher frequency creates narrow beam, better lateral resoltuion. more scan lines better lateral resolution.
positive predictive value in mammography
ppv1: positive/all cases from posititve screeners ,4.4% PPV2: positive/birads 4,5 , 25% ppv3: positive/positive biopsy results: 31%
DMSA
preferred radiopharamceutical to assess the determination of the differential renal function.
contraindications for breast radiation
pregnancy, previous breast radiation, multicentric or diffuse, collagen vascular disease
plagiocephaly
premature closure of a single coronal or lamboid suture, asymmetric head, can get harlequin eye.
scaphocephaly
premature closure of the sagital suture, m>f, no mental issues, associated with marfan's too. most common type of cephaly.
contraindications to breast conservation surgery
prior radiation to the same breast, multicentric(multiple quadrants), skin involvement, inflammatory breast ca, contraindication to radiation therapy (collagen-vascular disease)
inflammatory breast cancer
prior to excision, gets cooled down with chemo and radiation therapy.
coronary study drugs
prospective is axial, retrospective is helical beta blockers (hr <60): contraindicated in 2/3rd degree AV block, severe asthma, heart block, acute chest pain, recent cocaine snorting. nitroglycerine: given to dilate coronaries (contraindicated if severe aortic stenosis, hypertrophic cardiomyopathy, phosphodiesterase inhibitor)
Bladder extrophy
protrusion of the bladder through abdominal opening resulting from failure of fusion in utero, results in Manta ray sign-increased incidence of extruded portion to have adenocarcinoma (like urachal remnant)
when to get LMO instead of MLO
pt has pacemaker, kyphosis, pectus excavatum, avoid medial central line.
Ross procedure
pulmonic valve is switched to aortic valve, and prosthetic pulmonic is placed.
radial fold vs tear drop and hook signs
radial fold is the breast infolding a bit on itself, not indicative of rupture, is a thick line representing both layers coming together tear drop and nook signs are thin, representative of rupture, with fluid inside the invaginations.
types of radionuclide measurements
radionuclide -0.15microCi per milliCurie of Tc-well dose calibrator chemical- 10milligram of aluminum per ml of Tc- pH paper radiochemical- how much free tech for each study, 95% for NaTc (nonreduced form), 92% for sulfur colloid (too much and it'll aggregate in lungs). tested with TLC.
unroofed coronary sinus
rare ASD with fenestrated or totally unroofed coronary sinus strong association with persistent left SVC
Apical petrositis
rare complication of infectious otomastoiditis results when infection extends medially into a pneumotized petrous apex, most medial location is CN 6 canal (Dorelo's canal). Gradenigo's syndrome= lateral rectus palsy (abducens nerve) also hits the top two branches of the trigeminal nerve (so they get facial pain). Tx=Abx
Fibrodysplasia Ossificans Progressiva (FOP)
rare genetic disease where bone forms in wrong places (heterotropic bones) after minor injuries, replacing muscle tissue, etc. AD Most common in the sternocleidomastoid, begins like myositis ossificans, first edema distorting fat planes, then ossification over the ensuing weeks and months.
recordable event vs medical event (teletherapy)
recordable event: wrong dose, wrong med, wrong patient, if less than 50msV to whole body or less than 500msV to specific organ its a recordable event (does not need to be reported to the NRC). if more than these numbers, should be reported to the NRC, in writing within 15 days and via phone in 1 day.
compression in breast
reduced thickness so less scatter and lower kvp can be chosen lower kvp improved contrast reduced thickness less mAs breast smashed closer to Bucky so less geometric magnification less motion and less geo mag improved spatial resolution.
vignetting
reduction in brightness at the periphery of the image, only seen in II in fluoroscopy 2/2 internal geometry of the II.
near field in ultrasound
relates to lateral resolution NF = (transducer diameter)^2/ (wavelength) . longer wavelength means less NF. longer transducer has better NF. best lateral resolution at the focal depth/zone .
Heel effect
requires that the cathode be positioned to the thicker anatomy Increase if field size is increased. Decreases with increase source to image detector distance and greater anode angle, inversely related to source to image detector distance and anode angle. Also related to field size, the greater the field size, the greater the heel effect.
earliest sign of osmotic demyelination syndrome
restricted diffusion, it tends to spare peripheral pons and begin in the lower pons.
most common biliary anastomotic variant
right posterior segment duct (segments 6&7) drain into the left biliary duct (drains segments 2 and 4).
most common aortic arch anomaly with tetralogy of falot
right sided with mirror image
ring down artifact, comet tail, and reverberation artifact
ring down is due to beam encountering fluid within the tetrahedron of the gas particles which leads to multiple decreasing high echogenic lines reverberation is when the beam encounters parallel reflectors and goes back and forth, leading to horizontal linear echo lines comet tail is a form of reverberation the parallel structures are so close together that they are not perceived as distinct, however they decrease over distance 2/2 attenuation, giving the comet appearance.
localizing lesion only seen on CC
rolled views, superior tumor will move with the breast side you moves, if you move breast medially, its going to move medially, and inferior tumor will move laterally.
Choroid plexus cysts
round sonolucent areas in the substance of the choroid plexus of the lateral ventricles Isolated means nothing Associated with downs, More commonly with trisomy 18, turners.
free tech
salivary, thyroid and stomach
types of nuclear medicine probes
scintillation, well counters, and gamma cameras utilize crystal based scintillation detectors (NaI, CdZnTe, etc) coupled to a photomultiplier tube for radiation detection. Light pulses are generated in crystals from radaition , which are converted into a voltage signals by the PMTs. can detect small amounts (1mCi) (i.e. for wipe tests or in vitro studies (GFR, shilling test) Geiger-Muller counters, ionization chambers, and dose calibrators employ deterctos with gas filled chambers. Radiation from the radiopharmaceutical interacts with gas, causing ionization and generating electrical signal. Dose calibrator is a well type ionization chamber used to measure doses given to patients. ionization chambers are typically used to measure high exposure rates (from 0.1mR to 100R), such as those from pts receiving radioiodine therapy for cancer. (if pt receives more than 33mCi-on outpatient basis, precautions taken to ensure that no other person receives more than 500mrem(5mSv) from exposure. Activity is measured at 1m and 3m using the ionization chamber .
Tc-99m HMPAO leukocytes
see bright liver and spleen GI activity can be seen as early as 1-2hrs, so images of the abd and pelvis should be performed no later than 2 hrs after radiophram administration.
rice bodies
seen in RA and TB, bunch low signal sloughed off synovium
motion artifact and gradient direction
seen in phase encoding direction, irrespective of the direction of the motion. Swapping phase and frequency directions will not change this.
what type of nonmass enhancement is the most concerning
segmental
physiologic reaction
seizures, hypertensive emergency, unresponsive vasovagal, arrhythmia. Bronchospasm and anaphylactic shock are allergic induced after reaction.
direct flat panel in fluoro
selenium cover, and uses an electrode plate , xrays hit amorphous selenium creating current that goes to pad and each pad is a pixel. no photodiode or anything. Also used in mammo. most common in fluoro is the indirect.
balloon vs self expanded stents
self expanded stents are most useful in venous system, i.e. fix may-turner syndrome compared to balloon expanded stents.
ultrasound harmonics
send signal at a specific frequency, and receive signal back at a different frequency, improves lateral resolution and axial resolution, reduces reverberation artifact, you do lose some depth penetration bc you're dealing with higher frequency. Can help also lose sidelobe artifact.
when to do trans jugular instead of conventional liver biopsy
severe coagulopathy, massive ascites, massive obesity, mechanical ventilation.
kernels
sharpen edges (bone kernel) improves resolution but increases noise smoothing edges (abdominal kernal) improves nosie but decreases resolution (abdominal organs are small enough, you don't need that much resolution) can be done before or after reconstruction
myocardial volume and function is assessed in what MR view
short axis, used to calculate ventricular volume, size, mass and function.
brachycephaly
short broad head due to premature closure of the coronal and lambdoid sutures, so head grows sideways, associated with cleidocranial synostosis (short clavicles, brachycephaly and wormian bones).
microwave ablation
similar to RFA , cooks tumors. Generates more power, can cook bigger lesions, less ablation time, less susceptibility to heat sink effect (if lesion is close to any vessel greater than 3mm the vessel can dissipate heat), and it doesnt require a grounding pad.
single detector vs multidetector CT
single detector only uses one row of detectors and then the patient moves up the table. this takes time, uses a fan beam. Better geometric efficiency than multidetector bc theres no dead space (which happens with addition of multiple rows i.e. 128, 256 multidetector/slice CTs etc). multidetector uses multiple rows of detectors which allows for a cone beam to hit multiple places at once, faster imaging times. i.e. 128 row detector means you have 128 detectors along the z axis. in a 64 detector ct, with 0.5mm detector width, the beam width is 32, beam width is # detector rows x beam width.
intensifying screen in xrays
single emmulsion single cassette used in mammo, in others theres intensifying screens anterior and posterior to the base. have phosphors , made of rare elements to convert the xray to light properties of phosphors: -high atomic number so xrays absortion will be high (quantum detective efficiency) -emit a large amount of light per xray absorption (conversion efficiency) -light must be of proper wavelength to match sensitivity of the film (spectral matching). the thicker the phosphor layer, the higher the number of xrays converted to light high speed screens have thicker layers, detail screen have thin layers the higher the concentration of crystals, the higher the speed increased conversion efficiency results in lower exposure, greater speed also contributes to increased noise and decreased spatial resolution; high detail screens have a thin layer of small crystals.
x-ray generator
single phase goes from 0 to Max then to 0, kvp follows. triple phase uses three continues with slightly diff energies. allows for more quantity and quality (kvp avg is higher).
Bit-Hogg-Dube
skin stuff, chromophobe and oncotycomas in the kidneys, pulmonary cysts , thyroid carcioma, colorectalcarcinoma and parotid oncocytoma.
MRI spin echo
slice selection (use thin or thick gradient) then 90RF then phase and freq encoding sequences then 180 + two gradient slice sequences to get rid of side artifacts after 180. then another freq slice before read out.
most common appearance of medullary breast cancer
small circumscribed lesion usually doesnt have calcifications most common overall breast cancer is DCIS with segmental pleomorphic calcs being the most common presentation.
Tubular carcinoma of breast
small, spiculated. Best prognosis.
mag in mammo
smaller focal spot less mA longer exposure time
at what energy is PE and Compton scatter equal in soft tissue and bone
soft tissue 20kEv, bone 40 kEV.
complex breast cyst
solid and cystic component (birads 4) complicated cyst has internal echoes (can be birads 3).
sentinel event
someone dies, or seriously hurt, requires root cause analysis
adhesive capsulitis
space between the supraspinatus and the subscapularis, with the top bordered by the coracohumeral ligament the supraglenoid ligament and the superior glenohumeral ligament wrap around the long head of the biceps. decreased glenohumeral volume thickened inferior and posterior capsule enhancement of the rotator cuff interval post gad thickening of the axillary pouch (in a normal patient the axillary pouch is distensible)
what determines T1
spin lattice interactions
what determines T2
spin spin interaction, interactions that allow for net signal loss along the transverse magnetization overtime, regardless if you keep hitting it with 180 degree pulses.
GIST tumors are mostly in __ and ___, defect in __, which is a __. Tumors derived from __
stomach, jejunum, C-kit, tyrosine kinase, intestinal cells of Cajal Most commonly arise from submucosal, large and ulcerate 25% GISTS calcify
hyperparathyroidism
subperiosteal bone resorption of radial aspect of 2nd or 3rd fingers rugger jersey spine terminal tuft erosions
sebaceous or epidermal inclusion cyst
superficial, hypoechoic, thick wall, usually with a tract to the skin surface.
cerebellar vascular distribution
superior and superior vermis=superior cerebellar artery lower mid=aica lower peripheral and lower lower=pica
SLAP tear
superior labral tear from anterior to posterior around 12 oclock, will hit the biceps anchor, if the biceps invovled too you do debridement+biceps tenodesis not associated with instability
shoulder nerve entrapement
suprascapular notch-atrophy supra+infraspinatus spinoglenoid notch- atrophy infraspinatus quadrilateral space- axillary nerve (teres minor and deltoid); quadrilateral space(lateral is humerus, medial triceps, inferior teres major, superior teres minor) .
rotator interval components
supraspinatus inferior margin, superior margin of the subscapularis, also the roof is comprised of the superior glenohumeral ligament and the coracohumeral ligemants (which together make the sling for the long head of the biceps). thickening of the SGH and coracohumeral ligaments , in addition to thickening of the axillary pouch is seen in adhesive capsulitis.
pulmonary valve stenosis based on location
supravalvular-williams syndrom (like supravalvular aortic stenosis) valvular-noonan syndrome (male version of turners) infravalvular- TOF peripheral stenosis (alagille's syndrome, kids with absent bile ducts) pulmonary valve cusp has ant, right, and left, not posterior (aortic valve has right and left and posterior)
Posterior interosseous nerve injury
the bifurcation of the radial nerve (R) into the posterior interosseous nerve (PIN) and superficial radial nerve (SR). The posterior interosseous nerve (PIN) passes between the superficial (Ss) and deep (Sd) heads of the supinator muscle before exiting into the posterior compartment. -usually hits the supination muscle -ganglion cyst of the radial head can result in this
Time gain compensation
the function of the receiver that changes the brightness of the echo amplitudes to compensate for attenuation with depth
gastric band angle
the gastric band angle should be between 4-58 degrees ; the band should be less than 5cm below the left hemidiaphragm
Norwood procedure
the main pulmonary artery is attached to the aorta to provide systemic blood flow. A shunt is then placed to supply pulmonary blood flow, via the Blalock-Taussig shunt (the subclavian artery to the right pulmonary artery), the main pulm artery is now also separate from the right and left pulmonary artery (serving along with the hypoplastic aorta the systemic circulation), the Glenn and Fontan provide svc and ivc to right or left pulm artery, respectively, providing the passive pulmonic circulation.
dose length product (DLP)
the measurement of dose for the entire series of CT images. equal to the calculated dose per section mulitplied by the length of a CT acquisition along the z-axis. CTDIvol x length (z-axis) DLP is a close relative to effective dose, to determine cancer risk DLP is additive (mGy/cm), CTDI is not additive (mGy).
Adenomyosis
the presence of endometrial tissue growing through the myometrium T2 dark with internal small high T2 signal foci Usually the posterior uterine wall Junctional zone >12mm
electron capture
the process in which an inner orbital electron is captured by the nucleus of the atom that contains the electron, you convert a proton into a neutron , so the Z number decreases. Ga67, I-123, Ind-111, Thalium 201 all do it.I-131 is a B minus (gains a proton)
Elevational resolution
the resolution in the third dimension of the beam: the slice-thickness plane The wider the thickness of the crystal in the Z-axis, the more spread out the ultrasound beam, and worse the elevational resolution. The us beam is able to stay more narrow with higher TF. 1.5 dimension array also improves elevational resolution (allows you to create a focal zone in the elevation dimension, can get beam to be narrowing in the z dimension too).
The smaller the focal spot
the sharper the image appears; applies to mammo, plainfilms and ct
ultrasound transducer
the thickness of the transducer is equal to half the wavelength, higher frequency is therefore seen with thinner crystals.
myocardial bridging
therapy is beta blocker, worse with longer segment. Classic is LAD coursing through myocardium.
constrictive pericarditis
thickened pericardium (>4mm), most common cause now is CABG or radiation diastolic bounce (mid septal bounce towards left ventricle during early diastole)
ultraound probe
thin block- high q , long spatial pulse length, narrow bandwidth. thick block- low q , decreased spatial pulse length, broad bandwidth. better axial resolution.
Budd-Chiari syndrome
thrombosis of hepatic veins Central enhancement on portal venous phase, peripheral lack of enhancement Peripheral enhancement on delayed phase, central wash out.
whats the msot accurate serum tumor marker to detect papillary or follicular thyroid carcinoma
thyroglobulin
time in MRI
time= TRx phase encoding x Nex this applies to spin echo and gradient echo fast spin echo time = 1/echo train length 3d MRI= TRx phase encoding x Nex x slice thickness
tof mra vs phase contrast mra
tof uses gradient echo with saturation pulse to null arterial/venous blood. has small voxel size. 3d tof has even smaller fov, better spatial resolution. phase contrast uses bipolar gradients to create contrast from flow. tof is faster and less sensitive to signal loss from turbulent vessels.
chiari ii
tonsillar herniation, myelomeningocele (lumbar), tectal beaking, thin 4th ventricle.
cardiac nucs
transient ischemic dilatation (LV cavity bigger on stress)=usually left main or three vessel disease, diffuse subendocardial perfusion.
isomeric transition
transition from excited state to ground state with emission of gamma rays Z, N, and A all stay the same.
image contrast in xray
transmission and photoelectric absorption compton scatter gives you noise (freed electron gives you dna damage, the photon that hit that electron gives noise)
spread of infection in bones
transphyseal vessels are closed after 2 y/o (2-16), so no spread from metaphysis to epiphysis after 2 y/o.
Egg on a string
transposition of the great arteries, the pulmonary trunk and aorta are almost in front of one another, creating the narrow superior mediastinum, the opposite of TAPVR where you have snowman sign.
Meigs syndrome
triad of ovarian fibroma, ascites, hydrothorax
radial scar is associated with what cancer
tubular, slow growing of the cancers, so best prognosis. tubular, like radial scar often presents as spiculation.
sesamoid phalangeal ligament injury
turf toe- tear of the sesamoid-phalangeal ligament, usually secondary to hyperextension of the metatarsophalangeal space.
endoleaks
type 1 and 3 (fracture of the stent) are high flow endoleaks and need urgent repair, you can wait on the type 2 endoleaks.
types of dens fractures
type 1- tip type 2-neck, at the level of transverse ligament, which is why its unstable type 3 -below neck extending to lateral masses,if theres not too much deviation of the lateral masses its stable fx.
lemon skull
ultrasound feature in chiari ii and spina bifida, dissappears by 24 weeks.
post surgical physiologic enhancement on MRI timeline
up to 18-24 months, local recurrence 1-2%, and in 4-6 yrs mostly.
most common obstruction in pediatrics
upj obstruction
most common location for esophageal stenosis
upper and mid esophagus
Gland of littre
urethral gland , found in the bulbar urethra, at the dorsal aspect, only present with pathology, like strictures from gonorrhea or chlamydia. Gland of Cowper , found in the ventral aspect, the duct originates from the bulbar urethra. Male urethra= penile, bulbar, membranous and prostatic (posterior is the membranous and prostatic) (space between membranous and bulbar is the UG diaphragm).
electronic magnification in fluoro II
use a collimator to just sample the heart for example, then the II input phosphor and all just pick that so it gets magnified, but at the expense of less photons overall, so ABC kicks in and increases KVP and mA therefore increasing dose. Electronic magnification increases dose in II but not in FPD.
susceptibility artifact correction
use fast spin echo, not GRE, also any sequence with long TE makes it worse bc the T2* artifact will be noted. So it's worse in conventional spin echo vs fast spin echo.
bronchial artery embolization
use particles, never use coils in things you may need to reaccess (these things tend to rebleed) -for pulmonary AVMs you use coils. -hypervascular spine tumors (onyx, dries slowly) -upper and lower GI bleed (coils)
exposure
used in fluoro, relayed as air kerma (deterministic effect) and air kerma product (stochastic effect), measured in Gy
dAT study
uses I123 ioflupane , analog to cocaine to bind to dopamine receptor in basal ganglia. Need to block the thyroid prior to study. Images on SPECT acquired 4 hrs after administration of drug.
indirect flat panel detector in fluoro
uses a CsI scintillator that converts x ray to light, then the light goes to photodiode with tft (together photodiode and tft make a square, but most real estate taken up by the photodiode to send it to the tft. the greater the avg size of photodiode in relationship to tft in square the better. together called a DEL (detector element); fill factor=% of square the photodiode fills); the efficiency electron gets converted to light is called detective quantum efficiency (DQE), efficiency of going to xray to ouput signal. DQE of flat panels is better than screen films. you can combine multiple DELs into one large one , called binning. increases SNR but decreases spatial resolution (more photons but less difference in photons )
compound imaging ultrasound
uses electronic steering of probe to make multiple frames in different directions, sharpens edges and causes loss of post shadowing (can make cyst look solid) and really helps get rid of artifacts within cysts (which would make a simple cyst look like a complicated cyst). Also decreases speckle artifacts (side lobe, reverberation).
linearity and spatial resolution in nuclear medicine
uses the lead bar phantom , weekly, with Co-57 as the source (co-57 is GIIT, uses electron capture, so you release a proton in the process of Co-57 decay).
continuous pulse wave doppler
uses two transducers inside the probe, once continuously emitting and the other continuously receiving signal. this leads to greater velocity accuracy, but it cant tell depth or create an image, hence why its not used. not affected by aliasing is another pro.
Adrenoleukodystrophy
usually posterior callosal and occipital involvement lorenzo's oil movie only seen in boys
VCUG
voiding cystourethrogram, performed after the setting of multiple UTIs , or a renal ultrasound abnormality, not first choice for first UTI.
velamentous placenta
when blood vessels insert between the amnion and chorion, away from the margin of the placenta; leaves them unprotected and venerable to compression or injury. marginal cord insertion is almost a velamentous insertion (within 2cm of the placental margin).
TACE
when can you do transplant, and not TACE, <65 yo, 1 tumor <5cm, 3 tumors <3cm. can get sterile or chemical cholecystitis if the agent was injected into the right hepatic artery prior to the take off of the cystic artery.
When to do endarterectomy?
when occlusion >50% and symptomatic; 50-75% is >125cm/s, ICA/CCA>2.0.
radiation levels
white I: 0.5mrem/hr, at 1m nothing yellow II: does not exceed 50mrem/hr, and at 1m doesn't exceed 1mrem/hr yellow III: exceeds 50mrem/hr, OR at 1m exceeds >1mrem/hr
hemophilia
widened interchondylar notch, enlarged distal femoral diaphysis and epiphysis. joint space narrowing from synovitis. second most common is the elbow (enlarged radial head)
SSFP
workhorse of cardiac imaging, used to measure aortic root measurements as well, because its single breath, no motion. Single shot fast ... its gradient echo, uses gradient not the 180 pulse in spin echo
CT production
x ray tube->filter->collimator->grid->detector element (scintillator converts x rays to light->photodiode converts light to electrical signal->transistors carry signal to digital), has also a DEL (photodiode and transistor (tft) component)
Hodgkin's lymphoma staging
• Stage I: The lymphoma cells are in one lymph node group or one part of a tissue or an organ. • Stage II: The lymphoma cells are in at least two lymph node groups on the same side of the diaphragm, or the lymphoma cells are in one part of a tissue or an organ and the lymph nodes near that organ. • Stage III: The lymphoma cells are in lymph nodes above and below the diaphragm. Lymphoma cells may be found in one part of a tissue or an organ near these lymph node groups. Cells may also be found in the spleen. • Stage IV: Lymphoma cells are found in several parts of one or more organs or tissues, or the lymphoma cells are in an organ and in distant lymph nodes. Recurrent: The disease returns after treatment
