Endocrine and Exocrine
I-123 MIBG: what views do you need to get?
-Acquire anterior/posterior images of the head/neck, thorax, abdomen, and pelvis. -Acquire laterals if abnormal uptake observed.
I-131 MIBG: what views do you need to get?
-Acquire anterior/posterior images of the head/neck, thorax, abdomen, and pelvis. -Acquire laterals if abnormal uptake observed.
Dacroscintigraphy Positioning
-After the eyedrops are administered, the patient is placed in a sitting position for imaging. -Immobilizing the patient's head may be necessary to obtain optimal imaging; this may include securing the patient's head to the camera face or using an immobilizing vacuum pillow to limit patient motion.
Indications for Thyroid Scintigraphy
-Detection and evaluation of hyperthyroidism and hypothyroidism. -Detection and localization of metastasis from thyroid cancer. -Differentiation of benign from malignant nodules. -Detection and localization of benign ectopic thyroid tissue. -Evaluation of hetrogeneity of function within a thyroid gland. -Detection, localization, and evaluation of independent functioning or nonfunctioning nodule(s).
Indications for Adrenal medulla imaging
-Detection and localization of benign and malignant intra-adrenal and extra-adrenal pheochromocytomas. -Localization of site(s) of hormonal overproduction. -Detection and localization of neuroectodermal tumors. -Detection and localization of neuroblastomas (pediatric malignant abdominal mass and bone marrow tumors). -Detection and location of other neuroendocrine tumors such as carcinoid, medullary thyroid, paragangliomas (adrenal medulla), Merkel cell skin tumors, chemodectomas, small cell lung cancer, and schwannomas. -Evaluation of myocardial norepinephrine tumors -Metastatic pheochromcytoma
Dacroscintigraphy imaging
-Dynamic or static imaging may be obtained -Visualization of the nasolacrimal sac within 1 min after eyedrop administration, with drainage of activity from the nasolacrimal duct into the nasal cavity within 5 min, is considered a normal finding. -Drainage through the nasolacrimal duct to the nasal cavity can be variable, however, and others consider visualization of the nasal cavity within 10-15 min a normal finding. -Radioactivity not visualized after this time period may indicate a blockage. -Given the possible inter-patient variability, it is recommended that one side be compared with the other, rather than simply relying on quoted transit time values. -Evaluating both eyes simultaneously will be better for recognizing subtle differences between the drainage of each eye.
Abnormal Biodistribution
-Focal areas of increased activity that increases more over time. -Sporatic, unilateral, tumors show focal increased uptake. -Metastatic disease is seen in the axial skeleton, heart, lung, mediastinum, lymph nodes, and liver. -Neuroblastomas may arise anywhere there are nervous system tissue but most often are visualized as an abdominal mass, metastasizing early to bone and bone marrow. -Images at 72 hours provide maximal contrast between focus of activity and background.
abnormal results for Salivary gland imaging
-Increased uptake nonsymmetrically on one side or both sides of the face, different from bilateral uptake in the salivary glands. -Activity remains local after lemon administration. -Malignant (Warthin's) tumor presents increased concentration of readiotracer and will retain tracer within the mass. -Mixed tumors of the parotid -Lymphomatous infiltration. -Metastatic lesion -Abscess -Cyst(s) -Bacterial and viral inflammation: marked increase in uptake of the affected gland. -Space-occupying defect
Artifacts include
-Metal buttons, necklaces, or medallions. -Patient movement. -Compton scatter and downscatter from contaminants may contribute to the 123-iodine spectrum. -Improper collimation -Pertectnetate is not as accurate because it has low absolute uptake, high neck background, changing biodistribution, concentration in extrathyroidal tissue, and trapping without organification.
Abnormal results include
-Nonvisualization of the thyroid gland (subacute thyroiditis or Myxedema) -Graves disease -Hashimoto's thyroiditis -Thyroid carcinoma -Plummer's Disease -Autonomous multinodular goiter -Nodules: solitary or multiple -Cols and/or hot nodule(s).
Normal Salivary gland imaging graph
-Normal salivary gland function with 99mTc-pertechnetate. Images were obtained at 4 time points during study (A-D). -Shortly after injection (A), marked uptake in thyroid and milder uptake in salivary glands is seen. -Fifteen minutes later (B), uptake has further increased in parotid glands (arrowheads) and submandibular glands (arrows). -Immediately after lemon juice stimulation (C), activity is visualized in oral cavity (arrows). Three minutes later (D), 99mTc-pertechnetate has largely left salivary glands and is seen in oral cavity. -(E) Time-activity curve. First ROI has been placed over right parotid gland (upper left of image) and activity has been plotted as function of time. -Second ROI has been placed over scalp for purposes of background subtraction. -Curve demonstrates normal uptake by gland and appropriate rapid emptying in response to lemon juice stimulation. Similar analyses were performed of other 3 major salivary glands.
Patient prep for MIBG
-Take SSKI (saturated solution potassium iodide) or Lugol's solution the day before injection (400mg). -1 drop t.i.d. (3 times a day) beginning the day before injection and continuing for 6 days after injection. -Patient may be instructed to take bisacodyl 10 mg PO t.i.d. for 3 days before imaging to reduce bowel activity. -Patient can be treated with antihistamine before iodine administration if allergic. -Ideally no medications 2-3- weeks before examination.
MIBG normal distribution
-Uptake occurs in the pituitary, heart, salivary glands, thyroid, bladder, liver and spleen. -The gallbladder will be visualized in patients with renal failure. -The heart is visualized in patients with normal catecholamine's. -The adrenal medulla is seldom visualized. -The heart and adrenal medulla are more clearly visualized with 123-Iodine MIBG. -Areas of normal uptake diminish in intensity over time.
I-123 MIBG: specifics of imaging
-Whole body scan at 20cm per minute or less. -Statics should be at least 100K counts or 5-20 minutes each.
Whole body imaging with I-131
-can be done as a stand alone procedure with administration of a low dose of 131-Iodine -can be done after ablative therapy.
I-123 MIBG: SPECT or not?
-can include SPECT or SPECT/CT at the same time as imaging -Acquire SPECT in 3 degree intervals, 128x128 matrix, 20-30 seconds per stop.
Dacroscintigraphy is used to
-demonstrate patency of the system and to localize the general area of obstruction, which can be important for pre-surgical planning. -It also can be used postoperatively to evaluate whether the surgery was successful
Dacroscintigraphy administration
-is administered per eye to the supine patient with an eyedropper or a needleless 1-mL tuberculin syringe. -It is critical to ensure that eyedrop administration is performed with care to prevent contamination of the patient's face with radioactive drops, which could interfere with interpretation of the study. -If patients are teary, encourage them to blot, not smear, tears away with a tissue to limit potential of contamination. -Encourage the patient to allow the tears to drain down the lateral aspect of the face; allowing the tears to fall this way is preferable to having them fall naturally anterior to the face, which may interfere with the imaging of the medial nasolacrimal duct and nasal cavity.
How long should the patient be off of Anticoagulants
1 week
How long should the patient be off of Antihistamines
1 week
How long should the patient be off of penicillin
1 week
Three things to keep in mind to determine radiation exposure
1. The retained radioactivity in the patient. 2. The distance from the patient (Inverse Square law). 3. The duration of exposure (occupancy factor).
Space-occupying defect
1.5-2cm in diiameter, patchy decreases in activity in Sjogren's syndrome
Follicular carcinoma accounts for
1/3 of the cases of differentiated thyroid carcinoma
What is the normal weight of the thyroid?
10 - 30 grams but can increase during pregnancy
The dosage for salivary gland study
10 -15 mCi of pertechnetate
How long do you have to wait to take images of I-131
10 days post ablation
How long should the images take? What projections are needed for I-131 imaging?
10 minutes or 100,000 counts per view images with same projections as 123-Iodine.
Multinodular goiters
10% of the cold nodules may contain malinant cells
How long should each image be using 99mTc-Tc-O4-
100,000 - 200,000 count image or 5 minute acquisition.
Imaging agents for the Pituitary gland are:
111-Indium DTPA Pentatreotide Some pet compounds (11-Carbon and 18-Flourine)
Imaging agents for the Adrenal gland are:
123-Iodine MIBG 131-Iodine MIBG 111-Indium DTPA Pentetreotide
Dual phase imaging: matrix
125 x 125
The half life of I-123 is
13.22 hrs
tracer most commonly used is
131-Iodine (Sodium Iodide)
Imaging agents for adrenal medulla
131-Iodine MIBG (iodine-131-meta-iodobenzylguanidine) was approved over 30 years ago. 123-Iodine MIBG (iodine-123- meta-iodobenzylguanidine) is more frequently used today.
99mTc-Pertechnetate principal energy is?
140 keV
Dual phase imaging: wait time
15 mins
The principle energy imaged for I-123 is
159 keV
What is the imaging window for I-123
159 keV (with a ±20%) energy window
Energy level setting on thyroid probe?
159 keV for Iodine 123
I-123 MIBG: how many imaging periods
18 hours and 48 hours after
How long should the patient be off of T3 (Cytomel, Triostat)
2 to 3 weeks
How long should the patient be off of Potassium Iodide
2 to 4 weeks
How long should the patient be off of Vitamin and Mineral supplements
2 to 4 weeks
How long the patient be off of Cough and Cold preparations
2 to 4 weeks
How long should the patient be off of PTU (propylthiouracil)
2 to 8 days
Single cold nodules are
20-30% malignant
The dose of I-123 for a patient is
200-400 uCi, PO
I-131 MIBG: when can you start imaging?
24 hours post injection
24 hour values greater than
25% is suspicious for hyperthyroidism
what % of "cold" nodules are found to be thyroid carcinoma?
25-35%
123-Iodine MIBG (Adreview ®):dosing
3 - 10 mCi (111-370 MBq).
When using LEHR for 99mTc-Tc-O4-, how long is each image
300 seconds or 100,000 counts
normal 24 horu uptake values are
35-95%
The prinicple energy used for imaging I-131 is
364 keV
I-123 MIBG: when does imaging begin?
4 hours after injection
The normal uptake vaules for iodine is
4 hours: 5-20% 24 hours: 7-35%
How long should the patient be off of T4 Lexothyroxine (Synthroid, Levoxine, Levothyroid)
4 to 6 weeks
I-131 MIBG: how many imaging periods?
48 and 72 hours
survival rates for follicular carcinoma are
5 year: 91% 10 year: 85%
How much 99mTc-Pertechnetate is localized in the thyroid at total peak
5%
Thyroid uptake fraction
5%
Postpartum thyroiditis affects
5% of women
The dose for a patient receiveing I-131 whole body scan is
5-10 mCi
What is the recommended dose for 99mTc-Pertechnetate?
5-10 mCi (185-370 MBq) IV.
The normal dose for 99mTc-TcO4-
5-10 mCi injection
The dose for a patient receiveing I-131 for diagnostic imaging is
5-10 uCi
What is the usual dose for imaging I-131
5-50 uCi (1-10 uCi).
131-Iodine MiBG dosing
500 uCi (18.5 MBq), and 1 mCi
How long do images last for salivary gland studies
500K
Imaging agents for the thyroid are:
99mTC-Pertechnetate 123 Sodium Iodide 131 Sodium Iodide 18F FDG 111-Indium DTPA Pentetreotide
Radiopharmaceuticals used for parathyroid imaging are
99mTc Pertechnetate 201 Thallium Thallous Chloride 99mTc Sestamibi 99mTc tetrafosmin
Imaging agents for the parathyroid are:
99mTc-Sestamibi 99mTc-Sestamibi and 99mTc04- 99mTc-Sestamibi and 123 Sodium Iodide 99mTc-TC04- and Thallium 201
Less commonly used thyroid imaging agents are:
99mTc-Sestamibi Fluorine-18 FDG 111-Indium Pentatreotide
Dual phase imaging isotopes
99mTc-Sestamibi or 99mTc-Tetrafosmin
Imaging agent for Dacryoscintigraphy is:
99mTcO4
Goiters are caused by
>90% by iodine deficiency
"differentiated" cancer
A cancer in which the cells are mature and look like cells in the tissue from it arose.
Procedure for imaging for a salivary gland study first part
A dynamic blood flow study is performed immediately after intravenous injection for 3-5 s/frame for 1-2 min, 20 min of dynamic imaging for 2-3 min/frame follows to assess function of the glands.
What can effect a thyroid scan?
A number of medications, iodine-containing foods, and radiographic procedures using iodinated contrast
Anatomy of the Parathyroid
A small number of patients have 3, 5, or, occasionally, more glands.
Dual phase imaging procedure
Acquire images for 10 minutes per projection. Delay for 1.5 - 3 hours. Reacquire the images in the same projections for 10 minutes each. Display for comparison purposes.
How long should each image take for I-123 imaging
Acquired for 10 minutes or 50k to 100k counts (whichever is first)
What other images can be gotten if needed
Additional Anterior views should be obtained at greater distances if necessary to include the entire gland. Patients can be reimaged with a parallel-hole collimator.
whole body imaging with radioiodine I-131 may be indicated
After total thyroidectomy for differential thyroid carcinoma
contraindications for Adrenal medulla imaging
Allergy to iodine Interfering medicines (medicines that affect the adrenergic system). Antidepresents Amphetamines ACE inhibitors Calcium channel blockers Insulin Pseudoephedrine etc................................................
Negatives to Radiologic dacryocystography
Although this modality may provide greater anatomic detail, it is more invasive, delivers a higher radiation dose to the eye, and is not performed under physiologic conditions (the contrast is injected under pressure).
What views should be taken for I-123 imaging
Ant,RAO, and LAO projections
What markers should you use for I-123 imaging
Anterior marker with dual energy cobalt-57 (122 keV)and Iodine 123 (159 keV) if using cobalt ruler.
Dual phase imaging: views
Anterior, RAO and LAO position.
What images are required
Anterior, Right Anterior Oblique and Left anterior oblique, Anterior with marker
Dacroscintigraphy dosaging
Approximately 3.7 MBq (0.1 mCi) of 99mTc-pertechnetate in a saline solution
Thyroid carcinoma
Area of Thyroid carcinoma is blocked out so that the rest of the thyroid can be seen
Indications for Dacroscintigraphy
Assessment of lacrimal duct patency. Localization of functional nasolacrimal duct obstruction. Assessment of Epiphora. Assessment of surgical candidates. Assessment of inflammations (conjunctivitis, acute or chronic dacryocystitis). Assessment of paranasal sinus infections. Assessment post trauma, post surgery, tumors and systemic diseases causing nasolacrimal duct obstructions.
Sjögren Syndrome
Autoimmune disease affecting the salivary glands.
Metastatic Thyroid cancer
Before administration of I-131 for therapeutic purposes, it is essential that the endogenous TSH level be elevated 120 hours post injection
I-131 decays by
Beta particle emission with several gamma rays
Purpose of SSKI
Blocks free iodine uptake in the thyroid.
Method of localization MIBG
Blood flow, absorbed the same as norepinephrine into adrenergic tissue and stored in adrenergic granules.
How is I-131 administered
By capsule
How is I-123 produced
Cyclotron produced by proton irradiation of Xe-124
Abnormal Dacroscintigraphy
Dacroscintigraphy study demonstrating bilateral obstruction. Images at 3 time points reveal bilateral obstruction within nasolacrimal ducts (arrows).
The clinical features of hyperthyroidism are:
Decreased TSH Decreased T3 Decreased T4 Increased or Decreased 24 hr uptake
I-131 whole body bone scan with thyroid stun
Diagnostic 2 mCi I-131 scan revealed neck bed activity. Following treatment with 100 mCi of I-131 the post-therapy scan demonstrated almost no evidence of tracer uptake in the neck indicative of thyroid stunning. Note hepatic activity consistent with breakdown of radiolabeled thyroxine. Try to deliver at least 30,000 Rads.
DIT
Diiodotyrosine
Factors to consider about distance and time away from others
Dose rate estimates have been established for a distance of 1 meter from the source. To help insure safety, family members are to remain well beyond 6 feet as much as possible. The days (24 hour cycle) a patient may expose others is defined as the restricted time period.
The dose for I-131 whole body imaging
Doses of 1-10 mci (37-370 MBq)have been recommended, but the optimum dose remains controversial. 5 mCi.
The exocrine glands have
Ducts!
Dual phase imaging: how long,
Early imaging (after 10 minutes) and late imaging (1.5-3hours)
Apocrine glands include:
Eccreine or Sweat Glands (water secretors'), Sebaceous Glands (oily wax).
T3 and T4 levels are _____ when dealing with a patient with thyroiditis
Elevated
should 99mTc-Pertechnetate be used for uptake studies routinuely?
Enters the intra-thyroidal blood pool but is not organically bound and therefore should not be routinely used in uptake studies.
hyperparathyroidism
Excessive secretion of hormone
hypoparathyroidism
Failure of the parathyroid tissue to produce hormone
If a patient has thyroid cancer, what is the process they will go through before treatment with I-131
First surgery to remove thyroid Next get that TSH level back up! Then take off replacement thyroid hormone Then inject with recombinant human TSH Then I-131 therapy
What are the two categories of diseases of the thyroid?
Functional and structural
99mTc-Pertechnetate emmission is?
Gamma emission
What type of emission is the principle energy for I-123
Gamma emission
Thyotoxocosis
Graves disease
What are the important secretions of the anterior pituitary gland for nuclear medical techs
Growth Hormone, Thyroid-stimulating hormone (TSH), Adrenocorticotropic hormone (ACTH) Beta-Endorphin Prolactin (LTH) Luteinizing hormone (ICSH) Follicle-stimulating hormone (FSH) Melanocyte-stimulating hormone (MSHs)
the most common cause of hypothyroidism is
Hashimoto's thyroiditis
What is the principle energy and the energy window for I-131
Higher energy 364 keV gamma peak with a ± 20% window.
Normal results for a thyroid uptake imaging scan include:
Homogeneous tracer uptake. Left lobe may be smaller than right lobe. Possible pyramidal lobe. Straight or convex margins Uptake equal to or greater than the salivary glands.
Primary Hyperthyroidism
Hyperplasia accounts for the remaining 10-20% of all .
cretinism
Hypothyroidism in children as a result of a metabolic inherited defect
Most preferred radionuclide for thyroid imaging
I-123
what is being studied as a possible suitable substitute?
I-123
The most common treatment for hyperthyroidism in the united states is
I-131 therapy
Half value layer equation
I= 100%/2^n
Does I-131 Stun your thyroid
IT Can cause "stunning" in larger doses
99mTc-Pertechnetate is inserted by
IV injection
When can/should you start imaging a patient who has I-123 in their system
Images can be performed as early as 2-4 hours but best at 24 hours.
When should imaging be done when using I-131
Imaging should be done 16-24 hours post administration
how long should you wait before you start imaging with 99mTc-TcO4-
Imaging usually begins 20 minutes post injection.
Abnormal Dual Isotope
Initially; Area(s) of increased thallium activity outside normal thyroid tissue. Abnormal activity of Sestamibi or Tetrafosmin after subtraction of 123-Iodine on delays.
Normal Dual Isotope
Initially; Normal Thallium uptake, Normal parathyroid tissue does not accumulate Sestamibi, Tetrafosmin, or Thallium. Delays; heterogeneous washout.
Dual phase imaging: dose
Inject 20-25 mCi
Dual Isotope imaging
Inject Thallium 201 (2 mCi) Position patient supine, in the water's position. Image anterior neck and mediastinum with LEHR collimator for 100K counts. Do not allow the patient to move. Inject TC04- (10 mCi), wait 20 minutes. Acquire anterior thyroid image for 100K counts. Run subtraction program, separating thallium accumulation from Tc04- trapping. Thallium is used to identify the parathyroid adenoma.
How to administer 99mTc-TcO4-
Intravenous administration
Which foods should be avoided on a low iodine diet?
Iodinated Salts (table salt) Shellfish and Seafood Kelp and Seaweed Salted snack foods Red dye #3 (contains iodine) Limit dairy products (milk) Limit commercially baked goods Limit Soy products Limit Beans, Potato Skins, White Bread
Iodine pump
Iodine absorbed into the blood from the digestive tract, then The absorbed blood transports the absorbed iodine , in the form of iodide, into the thyroid gland where it is trapped by the thyroid follicular cells, which produces T3 and T4
Iodine Organification
Iodine is bound to tyrosine then coupled to make T3 & T4
How to make sure your physician knows the size of the thyroid
Keep distance consistant for all thyroid images use a ruler on one side of the thyroid to measure length use a Co-57 source to show the supra sternal notch
Metastatic Papillary cancer
Known history of papillary carcinoma of the thyroid with diffuse metastatic disease to the lung.
Excretion:
Large amounts of radioiodine will be excreted in the patients urine. Patients body fluids will be contaminated.
Predicted uptake for hyperthyroid patients
Late uptake= 24.84 + .726(early uptake)
Predicted uptake for euthyroid patients
Late uptake= 7.01+ 1.154(early uptake)
Hypothalamic-pituitary-adrenal axis
Limbic System
Dual phase imaging localization
Localizes in both thyroid and parathyroid tissue.
Patient Preparation
Low iodine diet for 3-10 days before scan discontinuing some thyroid meds
MIT
Monoiodotyrosine
What happens if hyperthyroidism is left untreated
More serious side effects can occur which include: bone loss and fractures, birth defects in pregnancy, and increased risk of a miscarriage. Cardiovascular damage, atria fibrillation, increased heart rate, stroke and blindness are other complications. Severe thyrotoxicosis can lead to thyroid storm, delirium, coma, and death
dacroscintigraphy image
Nasolacrimal apparatus is situated medial to eye and consists of superior canaliculus (SC) and inferior canaliculus (IC), common canaliculus (CC), nasolacrimal sac (NS), and nasolacrimal duct (ND).
subacute thyroiditis or Myxedema
Nonvisualization of the thyroid gland
Normal Dacroscintigraphy
Normal lacrimal gland study at 3 time points demonstrating bilateral drainage from eyes into nasal cavity
Why do we need to obtain oblique views
Oblique views better define nodules that may be on the anterior or posterior surface of the gland.
Procedure for imaging for a salivary gland study second part
Once the acquisition has started, the patient is asked to drink a mouthful of lemon juice via a straw and hold this in the oral cavity for a few seconds before swallowing. The patient is instructed to continue to hold as still as possible for the remainder of the acquisition. Static images in the right lateral and left lateral positions are acquired as needed.
Solitary nodule
One spot so hot could be more than one but can't tell
Dual-Phase Technique:
One tracer that localizes in both thyroid and parathyroid, but washes out of the thyroid and normal parathyroid, localizing in abnormal parathyroid only. Most advantageous.
thyroiditis
Outpouring of thyroid hormone from the inflammed thyroid
What are the important secretions of the Posterior pituitary gland for nuclear medical techs
Oxytocin ADH (Antidiuretic hormone)
What type(s) of collimators can be used for I-131 imaging
Parallel-hole Collimator, Pinhole collimator.
The main indication for parathyroid imaging is
Parathyroid adenoma
For thyroid therapy patients, success of the therapy is based on
Patient cooperation
What is the patient positioning for 99mTc-TcO4-
Patient is supine with the neck hyperextended (Water's position)
Completion of the "dose to the general public based on Patient-Specific Factors" form
Patient must sign and date this form and understand and initial the 7 instructions. CAlculations are based on administered dse
Confinement:
Patients must understand to remain alone and the materials they come in contact with may become contaminated and should be retained.
Contraindications of parathyroid imaging are
Patients on calcium medication Patients on thyroid medications (should be off for 5 days). Recent iodine contrast studies (wait 7-10 days).
Information needed by the tech
Pill counts at time 0 hours. Room background at time 0 hours. Patients thyroid counts at time 6 hours. Patients background at time 6 hours. Patients counts at time 24 hours. Patients background at time 24 hours. Room Background at 0, 6, and 24 hours. Decay factors at 6 and 24 hours.
Dacroscintigraphy What collimator is used
Pinhole collimator
The principle endocrine glands are:
Pituitary (anterior and posterior) Thyroid Parathyroid Islet cells of the Pancreas Adrenals (cortex and medulla) Gonads (ovaries and testes)
Hypothyroid symptoms include:
Poor muscle tone, Decreased sweating, Fatigue, Elevated cholesterol, Cold intolerance, Dry, itchy skin, Constipation, Weight gain, Depression ,Water retention, Muscle cramps, Bradycardial, Joint pain,Thin fingernails, Coarse hair, Goiter, Paleness, Hoarseness
Parotid glands
Primary set of glands
99mTc-Sestamibi:
Rapid uptake followed by slow washout. Cold nodules can appear hot on a sestamibi scan.
How does 99mTc-Pertechnetate work for imaging?
Reaches peak intra-thyroidal concentration at about 20 minutes, after that it "washes out".
Normal Salivary gland imaging
Reframed dynamic images (1 min per frame) show parotid and submandibular glands. Washout after lemon juice is seen halfway through study (3rd frame of 3rd row).
views needed for a salivary gland study
Right and left lateral head images, along with the anterior
I-131 MIBG: SPECT or no SPECT
SPECT! Acquire SPECT in 3 degree intervals, 128x128 matrix, 20-30 seconds per stop.
Merocrine glands include:
Salivary Glands, Pancreatic Glands, Certain Sweat Glands.
Countable standard procedure
Same as decay method;however, used a seperate pill instead of a decay factor.
Why LEHR for 99mTc-Tc-O4-
Search for ectopic tissue with the LEHR.
advantages to dual phase imaging
Several advantages to dual-phase imaging. Only one tracer and one injection. Computer subtraction not required. Radiation dose in decreased with the one injection.
Salivary Gland imaging
Sialography
Decreased uptake and decreased excretion of the pertechnetate from the salivary glands may occur in patients with
Sjogren syndrom
How to administer MIBG
Slow Intravenous injection over approximately 5 minutes.
99mTc-Pertechnetate
Sodium Pertechnetate
What can be used to help clear salivray glands when imaging with 99mTc-Tc-O4-
Some clinics give water or lemon juice
Sjögren Syndrome can be seen by
Space-occupying lesion 1.5-2cm in diameter, patchy decrease in uptake.
Specificity vs. Sensitivity MIBG
Specificity of 92.4% Sensitivity of 100%
I-131 MIBG: specifics of imaging
Statics should be at least 100K counts or 5-20 minutes each. Whole body scan at 20cm per minute or less
Normal results for Salivary gland imaging
Symmetric uptake in the parotid and submandibular glands. Uptake in sunlingual and thyroid glands, and nasal cavity. Significant reduction of activity inn salivary glands after lemon administration.
Medications to discontinue for a thyroid scan?
T4 Lexothyroxine (Synthroid, Levoxine, Levothyroid) T3 (Cytomel, Triostat) PTU (propylthiouracil) Potassium Iodide Vitamin and Mineral supplements Cough and Cold preparations Germicides and Antiseptics Salicylates (Bayer, Bufferin, BC powders, etc.) Fioroicet Steroids, Adrenal Cortical steroids Iodinated contrast (CT, Myelograms, Cardiac cath.) Penicillin Anticoagulants Antihistamines
Symptoms of Hyperthyroidism are all related to...
TSH blood levels
Hypothyroidism caused by an organification defect will cause
TSH to rise and diffuse gland enlargement (goiter)to occur.
Hypothyroidism caused by long term damage from graves disease , or chronic inflammation, will cause
TSH to rise with no enlarged gland (goiter).
Euthyroidism what hormones are normal?
TSH, T3, T4
Normal lab values
TSH: .3-3 U/ml Total T4: 4.5-12.5 mg/dl Free T4: .7-2 ng/dl Total T3: 80-220 ng/dl Free T3: 2.3-4.2 ug/dl
Half value layer
That thickness of material that reduces the exposure from a radiation source by one half
What emission of I-131 can "stun" thyroid follicular cells
The Beta emission of 131-Iodine
retained activity includes
The administered activity. The mass and function of then remaining thyroid tissue as reflected in the concentrations of serum free T4 and TSH. The radiopharmaceutical. The patient's hydration status. The patient's renal function.
What should you check before starting your calculations
The background readings!
Epiphora
The overflow of tears
Pertechnetate shows
The parotid and submandibular glands are clearly visualized, but the normal sublingual glands are not routinely seen.
Occupancy factor
The patient who arrives home has an occupancy factor of 0.25 (which means a person could be exposed to a patient treated with 131-Iodine at 1 meter 25% of the time. Sleeping reduces the occupancy factor to 0.33 because of the possible .3 meter distance.
Dacroscintigraphy Dosimetry
The radiation dose to the eye may be as low as 0.14 mSv/eye for an unobstructed eye and upward to 4 mSv in the presence of an obstruction. -Flushing both eyes with saline after the study is complete will help to clear remaining radioactivity.
Submandibular glands.
The second set of glands
Sublingual glands
The third set of glands
Other methods
These methods can confirm patency of the drainage system, but they provide no information on location of an obstruction or the presence of partial obstructions
Symptoms of hypoparathyroidism may include
This can cause muscle spasm and irritability and cardiac conduction problems.
Parathyroid adenoma
This condition results from a tumor in one of the parathyroid glands, or from hyperplasia (increase in the number of cells)of all four glands.
Completed "radioactive Therapy Directive"
This must include: patient name, address, medical record number, social security number, date of birth, diagnosis, radiopharmeutical to be administered, dosage, route of administration, and name of requesting physician
Inverse square law
This relationship indicates that doubling the distance from a radiation source decreases the radiation level by a factor of four
How are the images done for the second set of imaging
This scan is obtained with the patient positioned as in the "pre-stimulus" dynamic acquisition for 2-3 min/frame for 20 min.
Critical organ of MIBG
Thyroid
Role of nuclear medicine with the adrenal medulla
To identify the location of catecholamine-synthesizing tumors, mainly either pheochromocytoma , paraganglioma or neuroblastomas.
Dual phase imaging
Tracer washes out of the normal thyroid tissue more rapidly than abnormal parathyroid tissue.
99mTc-Pertechnetate organified or not?
Trapped, but not organified by the thyroid gland.
T/F: The hot nodule may or may not suppress the remaining thyroid.
True
111-Indium Pentatreotide:
Tumors that express Somatostatin receptor sites. Identify the extent of disease and to localize neuroendocrine tumors. Hashimoto's type with lymphocytic infiltration, and medullary thyroid cancer have been assessed.
Dual-Tracer Technique
Two tracers, one that delineates normal thyroid tissue (99mTc-TC04- or 123-Iodine), and one that localizes in both thyroid and parathyroid tissue (sestamibi or thallium). Least advantageous.
What is the critical organ for 99mTc-Pertechnetate
Upper Large Intestine
Survival rate for papillary carcinoma is
Very high 5 year is 96% 10 year is 93%
Minimal Contact:
Visitors will be provided with specific rules regarding the amount of time spent in contact with the patient, and the distance that must be maintained from the patient. No children and pregnant women near the patient.
Indications of parathyroid imaging are
Visualize and detect primary and secondary parathyroid cancer. Localization of parathyroid tissue prior to surgery. Used in postoperative patients with persistent or recurrent hyperparathyroidism to detect persistent, aberrant, or ectopic parathyroid tissue.
Abnormal Dual Phase
Washout of thyroid with focal increase uptake of tracer on delayed images. Obliques and SPECT (cutoff 5, power 10, butterworth) can be helpful after delays.
Patient positioning for salivary gland study
Water's position
Dual isotope study techincal considerations
When doing dual-tracer technique, 99mTc04- may be administered first to minimize the amount of time the patient must remain still. After 99mTc administration, the patient does not need to be positioned until the tracer has concentrated in the thyroid scan. The method necessitates correction of the Thallium image for 99mTc down-scatter.
When using LEHR for 99mTc-Tc-O4- , obtain what views
When using LEHR, obtain anterior view of (with and without markers), RAO and LAO.
What is I-131 normal used to image
Whole body scanning for cancer metastasis
Thyroid uptake probe requirements
a 2 inch thick sodium iodide crystal and a flat field collimator connected to a pulse-height analyzer and scaler.
a dye or saccharin test
a dye or saccharin solution is administered to the patient's eye; the patient verifies proper lacrimal drainage when the dye is presented in the mouth or the saccharin is tasted in the mouth.
Hashimoto's thyroiditis
a form of thyroid inflammation caused by your own immune system
Primary hyperparathyroidism is most commonly associated with
a functioning parathyroid adenoma (80-90%).
thyroiditis is often considered
a malfunction of the immune system
The hot nodule can also represent
a normal variant or surgical remnant
parathyroid hormone (PTH)
a polypeptide, that regulates calcium and phosphorus levels and metabolism.
mechanical obstruction
a portion of the nasolacrimal drainage system may be obstructed.
Prolactin (LTH):
a protein, peptide hormone associated with lactation. Classified as a gonadotropin.
A single solitary nodule presents
a significantly higher risk of cancer than multiple cold nodules.
Instead of having two different sections you can do
a single acquisition with both parts One may choose to set up the dynamic acquisition for 40 min and administer the lemon juice via a straw to the supine patient 20 min into the dynamic acquisition.
Thyroid carcinomas show up in radioiodine scan as
a single solitary "cold" nodule
Papillary Carcinoma
accounts for 2/3 of the cases of differentiated thyroid carcinoma.
Written instructions
actions recommended to maintain doses to other individuals ALARA if the total effective dose equivalent to other individuals is likely to exceed 100 mRem provided by licensee
how does 99mTc-Pertechnetate localize
active transport
Localization of 99mTc Pertechnetate
active transport into normal tissue.
I-123
actively transported and organified by the thyroid gland
Once identified by gamma probe and resected
adenomas should register 20 to 50% higher than background.
Follicular carcinoma is more
aggressive than papillary carcinoma
Antidiuretic hormone:
aka Vasopressin. A peptide hormone regulates water, glucose, and salts in the blood. Helps regulate blood pressure and kidney reabsorption. Plays a role in social behavior.
Thyroid disease is prevalent
among patients with hyperparathyroidism.
Sjogren syndrom
an autoimmune disorder that affects exocrine glands such as lacrimal and salivary glands.
Make sure to get at least
an early uptake but both uptakes are important
hyperthyroidism is characterized by
an increase in metabolism and the effects of increased metabolism on the entire body
Scintigraphy normally includes
an uptake scan
Remaining 5% of cases of thyroid cancer are:
anaplastic, medullary, lymphoma, and metastatic disease
The two parts of the pituitary glands are
anterior and posterior
TSH is produced in the
anterior pituitary gland
subclinical hyperthyroidism and subclinical hypothyroidism
are used where the diagnosis is based upon an abnormal TSH level rather than clinical symptoms
Scintigraphy is the only imaging modality that
assesses salivary gland function.
How far should the thyroid uptake prod be from the patient's neck?
at least 10-cm but normally 25-30cm
Written instructions
at minimum to include the SNM pamphlet "guidelines for patients receiving radioiodine treatment:, with patient education form
Why is I-125 not preferred
because I-125 has too low a photon energy for thyroid uptake use.
Why is there a Higher radiation absorbed dose to the patient
because of the Beta particle and high energy gamma.
Why is thyroid uptake nonspecific?
because the value is influenced by factors other than intrinsic thyroid function; specifically total iodine intake.
The location of the thyroid is
below the thyroid cartilage which forms the laryngeal prominence, or 'Adam's Apple') and extends to the level of the fifth or sixth tracheal ring.
Cold nodules can represent
benign adenoma, cyst, hematoma, and inflammatory conditions also.
Warthin tumor
benign tumor of the warthin duct.
The diagnosis of thyroid carcinoma can only be confirmed by
biopsy
Which area should the tech try to avoid when getting background counts
bladder
exopthalmous
bulging eyes
what type of shape is the thyroid?
butterfly shaped
TSH level of 30 μU/ml or more.
can be reached by waiting 4-6 week or more after thyroidectomy or after stopping treatment with thyroxine (T4).
I-123 is administered by
capsule
De Quervain's thyroiditis
caused by a severe case of the "flu" that enters and destroys all or part of the gland
hypoparathyroidism results in
causing a gradual reduction in serum calcium (hypocalcemia).
functional obstruction
causing inefficient drainage may be due to medical issues such as facial palsy or exophthalmos.
holocrine glands
cells are permitted to break up to produce compounds, and discharge desired secretions
non-functioning is shown by a
cold nodule
"pregnancy verification" form
completed and signed by all female patients between the ages of 10-50 years verifying "non pregnant" status
"patient education in nuclear medicine" form
completed and signed by the patient
"informed consent form"
completed and signed by the patient, authorized user, and technologist
Nuclear Medicine is the only modality that
confirms the functional nature of the anatomic finding; however, it can be seen by CT, MRI, and ultrasound
completed and signed "travel document"
copy and give to patient
Nasolacrimal apparatus as seen on
dacroscintigraphy.
signature of authorized physician
date and time on the administration record
What are the different types of calculation methods that can be used for a thyroid scan?
decay method countable standard predicted uptake
Iodine uptake is normally ______ when dealing with a patient with thyroiditis
decreased
TSH levels are _____ when dealing with a patient with thyroiditis
decreased
TSH levels are _________ when a patient has toxic nodular goiters
decreased
When dealing with a patient who has hypothyroidism iodine uptake levels are normally
decreased
Sensitivity _____ as the aperture diameter_____
decreases, decreases
as the aperture diameter _______, the resolution ______.
decreases, improves
Lucite Neck Phantom
designed to simulate a average patients neck tissue attenuation.
Hypothalamic-pituitary-gonadal axis controls...
development, reproduction, and aging in animals.
Goiter
diffusely enlarged gland due to swelling
Submandibular glands empty
directly into the oral cavity thru the Warthin ducts.
6 weeks before scan/treatment:
discontinue synthroid and begin Cytomel
Follicular carcinoma is most likely to spread to
distal sites including the skeleton
Radio Active Iodine Uptake (RAIU) is used to
distinguish a hyper-functioning gland from a normal gland.
Why can the 24 hr uptake be decreased for hyperthyroidism
due to thyroiditis
Why can the 24 hr uptake be increased for hyperthyroidism
due to true hyperthyroidism
decay factor equation
e^-(lambda)t
How is I-131 produced
either a fission product (uranium, plutonium) or by neutron bombardment
I-123 decays by
electron capture
Clinical hyperthyroidism have symptoms of
elevated T4 Suppressed TSH
hypercalcemia
elevated serum calcium
Thyrogen has helped body scan imaging by
eliminating the need for the patient to be hypothyroid before the can
Thyroiditis is excessively _______ thyroid
enlarged
Hashimoto's thyroiditis
enlarged gland with mottled areas
Graves disease
enlarged gland, elevated T3 and T4 and low TSH
Localization of 201 Thallium Thallous Chloride
enter the thyroid and parathyroid via blood flow.
Ophthalmologists may choose to
evaluate the nasolacrimal drainage system in the office with a dye or saccharin test.
Normal Salivary glands should
exhibit a significant decrease in activity almost immediately after lemon stimulation, with a resultant increase in activity in the oral cavity.
Most of the glands found in the body are
exocrine glands
PET imaging positioning
eye to thigh
"medical reconciliation" form
filled in and examined by the authorized user
Palpable nodules are imaged to
find out if it is a cold or hot nodule. to test the function of the rest of the thyroid
Toxic nodular goiter normally has a _________ _________ iodine uptake
focally increased
I-131 is only used in treatment of
follicular and papillary carcinomas
Salivary duct obstruction may be caused by
food, foreign bodies, mucus plugs, tumors (Warthin's tumor), cysts, surgery, or trauma
written prescription label
from capsule vial
two different types of structural disorders are
functioning and non-functioning
What is a hot nodule?
functioning nodule(s) that organify radioactive iodine
What type of camera and collimator is used for thyroid imaging
gamma camera and pinhole collimator
BE careful of patients who have
had other radioactive tracer studies done
Calcitonin
has a role in calcium homeostasis
When dealing with a patient who has hypothyroidism TSH levels are normally
high
Most radiation exposure for I-131 is from
high-energy gamma rays
T4 is present in plasma in a _______ concentration than T3.
higher
The pituitary gland regulates
homeostasis
functioning is shown by a
hot nodule
The thyroid gland controls...
how quickly the body uses energy, makes proteins, and controls how sensitive the body should be to other hormones.
Endocrine glands
how the body communicates and coordinates with the nervous system, reproductive system, pancreas, liver, kidneys and fat to maintain balance, or homeostasis, with reproduction, growth and development, and energy levels and responses to external stress and injury
hyperparathyroidism causes
hypercalcemia
99mTc-Pertechnetate is best used for...
identifying size and location of thyroid tissue. **Can be used for localizing ectopic thyroid tissue (as can 123-Iodine) anywhere in the body, with limitations.
T4 can vary but still be normal in what conditions?
if increased consider pregnancy, estrogen therapy, decreased consider androgens or ASA therapy
When developing protocols
image a thyroid phantom of known size
What is the difference imaging with a pinhole collimator?
image size varies with distance and image is flipped upside down so make sure you flip it right side up before you start imaging
Luteinizing hormone (LH):
in females stimulates ovulation, in males stimulates production of testosterone. Works in harmony with FSH.
What views should be obtained for 99mTc-Tc-O4-
in the Anterior position, the RAO, and LAO position. Additional Anterior marker view is also acquired.
Parotid glands are located
in the cheeks, below and in front of the ears.
When does peak activity occur for a salivary gland study
in the glands within 10 to 21 min.
Parotid glands are secreted
in the saliva into the oral cavity thru the Stensen's ducts.
How should that patient be laying on the imaging table
in the supine position, neck hyperextended.
Follicular carcinoma is more commonly
in women over 50
Dacroscintigraphy Static imaging
includes a 1-min image obtained immediately after the administration of eyedrops, followed by 1-min static images obtained at 5, 10, 15, and 20 min.
Insufficient tear formation may be caused by
including Sjögren's syndrome, inflammatory conditions, allergies, or radiation treatment, or the problem may be due to medications, age, or environmental conditions.
T3 and T4 levels are _________ when a patient has toxic nodular goiters
increase
TSH can _______ in a patient with secondary hypothyroidism
increase
hyperthyroidism is caused by
increased production and release of thyroid hormone from the thyroid gland
Graves disease is caused by
inflammation of the eye muscles by attacking autoantibodies
Normal Dual Phase
initially; heterogeneous uptake of the tracer by the thyroid gland. Delays: heterogeneous washout of the tracer with no lingering focal points of uptake.
merocrine glands are generated by
intact cells
Endocrine glands secrete into
internal environment
The functions of the endocrine are
interrelated
Sublingual glands empty
into the oral cavity thru sublingual or Warthin ducts.
How is the dose for the salivary gland study administered
intravenously.
The thyroid hormones T3 and T4 are manufactured from
iodine absorbed into the blood from the digestive tract
The most common cause of hypothyroidism worldwide is
iodine deficiency
Thyroid uptake
is a nonspecific measure of thyroid function
Tertiary hyperparathyroidism
is a state of excessive secretion of parathyroid hormone after longstanding secondary hyperparathyroidism and resulting in hypercalcemia. Could also even be defined as hyperparathyroidism that still exists after renal transplant.
Xerostomia
is a symptom that can occur in thyroid disorders, sarcoidosis, after radiation therapy, dehydration, after certain drug ingestions, and from collagen-vascular systemic disorders, such as Sjögren syndrome.
Radiologic dacryocystography
is an alternative imaging modality for assessing the nasolacrimal system.
Secondary hyperparathyroidism
is caused by the overproduction of parathyroid hormone secondary to a chronic abnormal stimulus for its production. Typically, this is due to chronic renal failure or vitamin D deficiency.
Mortality rate of thyroid cancer
is less than 1% of all cancer deaths, however, exceeds that of all other endocrine tumors
How can you tell if there is an obstruction in sailvary gland imaging
is poor or absent clearance of activity after lemon stimulus.
A single palpable nodule
is suspect for thyroid carcinoma until proven otherwise
What is the purpose of I-131 whole body imaging
is to identify residual functioning thyroid tissue and/or areas of metastasis.
99mTc-Pertechnetate decays by:
isomeric transition
Administration of imaging agent for Dacryoscintigraphy
just a drop near the lacrimal glands and should drain quickly
When using a pinhole collimator it is important to
keep your distance consistant and use the right lead pinhole insert
hypercalcemia can result in
kidney stones, bone mineral loss, and kidney calcification
sestamibi critical organ
large intestine
The right lobe is normally _____ than the left lobe
larger
doing computer subtraction in dual isotope studies can
lead to false positives.
After the first set of pictures, what is administered before the second set of images
lemon juice orally
Differentiated cancers tend to be decidedly ____ __________than undifferentiated cancers composed of immature cells
less aggressive
Papillary cancer is _____ ___________ than follicular cancer
less aggressive
When having a hot nodule, this means
less chance of malignancy than cold
What does a single hot nodule mean?
likely to be a functioning adenoma
During the pre-stimulus phase, an increase in uptake may be due to
local inflammation or infection.
24 hour uptake value below 12% is considered
low
When dealing with a patient who has hypothyroidism T3 and T4 levels are normally
low
What are target points?
may be cells, tissues or organs
Obstructions in the salivary glands
may cause painful swelling in the patient, especially when salivary flow rates are high.
Dual phase imaging: why?
may demonstrate retention of the tracer in abnormal parathyroid tissue that becomes more obvious on the delayed images.
sub-classifications of exocrine glands
merocrine glands, holocrine glands and apocrine glands
99mTc-Pertechnetate is produced by
molybdenum generator
After RAI therapy patients must be
monitored to make sure that they do not go into hypothyroidism
T3 is ____ metabolically active than T4
more
Graves disease
more severe form of hyperthyroidism
Why are 24 hour uptake values important?
most practical and reliable interval because it provides better discrimination between hyperthyroid, euthyroid, and hypothyroid populations than earlier time points.
There are two different types of toxic nodular goiters they are:
multiple or solitary hot nodules
Dosage administered
must be documented in NMIS and written directive
Females in child bearing range
must have a negative pregnancy test completed, reviewed by authorized user and on record with nuclear medicine department
I-131 causes
mutation and death in cells
adult hypothyroidism
myxedema
What is a receptor needed for?
needed in order to receive the message transmitted
Should a patient that is pregnant recieve an I-123 capsule
no
Should a patient that is pregnant recieve an I-131 capsule
no
Endocrine glands have
no ducts
Should children be given I-131 for diagnostics? What should be used instead
no, I-123 should be used instead
Structural Disorders
nodules and other changes in anatomy.
Anatomic changes in the pituitary is _______ in normal pregnancy
normal
A person with Euthyroidism normally has a
normal iodine scan
Euthyroidism
normal thyroid!
When comparing one eye with the other
one must assume that one eye is functioning normally and be aware that the bilateral obstruction of varying levels may exist.
The size of the thyroid gland is...
one of the largest endocrine glands
Beta-Endorphin
opioid peptide neurotransmitter. Has an analgesic effect. Increased relaxation, promotes well being, slows cancer growth, boosts immune system.
Hypercalcemia symptoms include
orthopedic complications from bone mineral loss
Functional disorders
overactive and underactive thyroid gland.
Hyperthyroidism
overactive thyroid
Completed "radiocative therapy administration record" form
page 2 of therapy directive on day of administration. This must include: proper verification from picture ID of the patient, name, address, social security number, and date of birth. Verification patient is not pregnant or breast feeding (if applicable) must be completed. Isotope used, chemical form, supplier, receiving date and prescripton numbers, label and assay strength, dosage administered by, and the tech signature must also be documented. Documentation must include verification that the patient had a total thyroidectomy
two __________ glands are on each side of the thyroid?
parathyroid
The parathyroid glands synthesize, store and secrete what?
parathyroid hormone (PTH)
Localization of 99mTc Sestamibi
passive transport into normal tissue, remaining longer in adenomous tissue.
Localization of 99mTc tetrafosmin
passive transport into normal tissue, remaining longer in adenomous tissue.
Lymphomatous infiltration
patchy areas of decreased concentration and may have normal count rates; with increasing infiltration, count rate decreases.
Mixed tumors of the parotid
patchy decrease in activity in the area of the lesion; lesion may have normal or increased count rate.
false-positives can occur in saccharin tests if
patients are unable to taste the saccharin in their mouth or if the dye is present but simply not visualized.
Procedure before 1997
patients receiving more than 30 mCi (1110 MBq) of 131-Iodine were hospitalized.
Melanocyte-stimulating Hormone (MSH):
peptide hormone, causes increased pigmentation.
What patient history should be asked about
pertinent lab values, surgical history, cancer history, medications, recent iodine studies, pregnancy, etc...
What type of collimator is used for 99mTc-Tc-O4-
pinhole collimator.
secondary hypothyroidism is possibly caused by
pituitary tumor that interferes with pituitary production and release of TSH
Oxytocin:
polypeptide best known for its role in female reproduction. Released in large amounts during labor facilitating birth and breastfeeding. Has a role in various behaviors-referred to as the "love hormone".
Adrenocorticotropic hormone (ACTH):
polypeptide that is released most often during stress. Releases corticosteroids and cortisol. Part of the adrenal-hypothalamus-pituitary loop.
Which side of the thyroid are the parathyroid glands found?
posterior
Sjögren Syndrome occurs in
postmenopausal women.
Records that must be kept on file
prescription labels original prescription therapy directive informed consent travel document medication reconciliation patient education patient information pregnancy documentation release calculations
Radionuclide imaging is only useful in
primary hyperparathyroidism
Hyperparathyroidism is usually subdivided into
primary, secondary, and tertiary hyperparathyroidism.
Growth hormone
protein-based peptide that stimulates cell growth. (Human Growth Hormone) Secreted by the somatotroph cells
Toxic nodular goiter
pulmmer's disease
Thyroid storm is
rare but severe complication of hyperthyroidism
Hypothalamic-pituitary-adrenal axis controls...
reactions to stress and regulates many body processes, including digestion, the immune system, mood and emotions, sexuality, and energy storage and expenditure.
Follicle stimulating Hormone (FSH):
regulates the development, growth, pubertal maturation, and reproductive processes of the body.
Hypothalamic-pituitary-thyroid axis is responsible for...
regulation of metabolism
Our jobs as techs is to
reinforce information provided by the referring or treating physician Answer all questions the patients have
Thyrogen
rhTSH : recombinant human thyrotropin Genzyme
Sjögren Syndrome symptoms are
rheumatoid arthritis, xerostoma (dryness of the mouth caused by malfunctioning salivary glands), and keratoconjunctivitis sicca (dryness of the eyes).
Holocrine glands include:
secretory product is form in the cytoplasm (Skin Sebaceous Glands).
Written prescription
signed and dated by the ordering physician. This include patient name and proper diagnosis
What are the two different types of ducts
simple or compounded
Abscess
smooth and round with no activity, tender to palpation.
Cyst(s)
smooth and round, no activity, not tender to palpation.
Plummer's Disease
solitary or multiple nodular goiter with elevated
Symptoms of Thyroiditis is
sore throat
Metastatic lesion
space-occupying and slightly ragged with no activity.
Thyroid-stimulating hormone (TSH):
stimulates the thyroid to release T3 and T4. A glycpoprotein controls thyroid function. Thyroid system is the the pituitary-hypothalamus-thyroid loop.
How does ACR feel about the use of I-131 for diagnostic use
strongly discourages it
What does I-131 do to the thyroid cells
stun them
the "stun" thyroid follicular cells can interfer with
subsequent 131-Iodine uptake when the tracer is used for therapy.
The "gamma probe" provides
surgical assistance of removal in the OR.
131-Iodine MiBG used for
suspected metastatic pheochromocytoma
The symptoms for thyroid storm include
tachycardia, arrhythmia, vomiting, diarrhea, increased body temperature (104 degrees F), coma, death.
What is a cold nodule?
that do not organify radioactive iodine
In the post thyroidectomy patient, the critical organ for I-131 is
the Bladder wall (2.3 Rad/mCi).
Imaging of the glands with pertechnetate is easy because
the ability of the glands to trap and transport the pertechnetate anions (as well as iodides) from the surrounding blood supply into the salivary glands. The ions are also actively secreted into the saliva, thus makes excretion easily assessed.
Maximum sensitivity can be reached in a whole body I-131 scan when looking for metastases by
the absence of significant residual functioning thyroid tissue, since it requires a TSH level of 30 μU/ml or more.
RAIU measures
the amount of radioactive iodine taken up and retained within the thyroid gland.
Increased levels of circulating hormone signal
the anterior pituitary to suppress TSH secretion.
the internal environment in which the endocrine secrets into
the blood and extracellular fluid.
Saliva initiates
the chemical breakdown of food and is continuously secreted into the mouth.
Hypothalamic-pituitary-gonadal axis
the effects of the hypothalamus, pituitary gland, and gonads as if these individual endocrine glands were a single entity as a whole.
The exocrine glands secrete into
the external environment
thyrotropin-releasing hormone (TRH) produced by
the hypothalamus.
The bridge between the two lobes is called
the isthmus
Papillary carcinoma spreads through
the lymphatic system
The pituitary gland is
the master gland!
Dacroscintigraphy
the nuclear medicine lacrimal gland study, is a noninvasive, low-radiation-dose method of evaluating the nasolacrimal drainage system
Sensitivity is increased if
the patient has complied with a low iodine diet and by determining that the patients TSH level is greater than 30-50 mU (milliunits) per liter.
NRC revised 10 CFR 35.75
the patient may be released from the hospital either when the activity levels fell below 30-33 mCi or the dose rate at 1 meter dropped below 50 mRem/hr.
Secretion of PTH is regulated by
the plasma concentration of ionized calcium
Information that should always be given to the patient is
the reason for the procedure the length of the procedure the physical requirements during the procedure pre and post treatment instructions.
The two lobes of the thyroid are
the right and left lobes
What can be seen in a I-131 whole body scan?
the salivary glands, thyroid tissue remnants, esophagus, and thymus, as well as distant metastasis. Activity can also be seen in the liver, this may be consistent with the breakdown of radiolabeled thyroxine (T4).
The diameter of the aperture of the lead pinhole insert determines
the spatial resolution of the system
The half value layer depends on
the stopping power (linear attenuation coefficient - l.a.c.) and the energy and type of radiation.
pyrimidial lobe
the third lobe of conical shape frequently arises from the upper part of the isthmus, or from the adjacent portion of either lobe, but most commonly the left, and ascends as far as the hyoid bone
Calcitonin is produced by
the thyroid
If a patient still has a thyroid I-131's critical organ is
the thyroid
The critical organ for I-131 is
the thyroid gland
The critical organ of I-123 is
the thyroid gland
goiters occur due to
the thyroid not functioning properly
Apocrine glands dispense the cells with
their secretion
A toxic nodular goiter means that
there is an excess hormone production
What effects the 24-48 hour uptake values
they are effected by the rate at which iodine is lost from the gland.
Salivary glands contain
three paired exocrine glands that produce saliva
most common endocrine neoplasm is
thyroid cancer
Primary hypothyroidism is caused by
thyroid hormone deficiency, usually as a result of the failure of the thyroid gland to synthesize and release thyroid hormone.
In normal circumstances RAIU
thyroid uptake at 2-6 hours reflects iodine trapping and organification within the gland.
The difference between thyroiditis and graves disease
thyroid uptake values
Patients should not be given
thyroid-blocking agents, such as iodide or perchlorate, within 48 h before the scan
The most common etiology of hyperthyroidism is
thyrotoxicosis
Goal of ablative therapy is
to administer 30,000 Rads to any possible thyroid remnant.
Salivary gland imaging may be used
to assess the function of the salivary glands, to evaluate salivary duct patency, or to help characterize tumors.
The main clinical indication is
to evaluate dryness of the mouth, or xerostomia.
What is the goal of thyrogen
to increase TSH levels.
It is important to keep the patient unaware of the lemon juice stimulation until the time of administration because
to prohibit psychological stimulation of the glands.
The most common of hypothyroidism in non developed countries is
toxic multinodular goiter
Thyroid hormone synthesis depends on
trapping and organification of iodine
What is I-131 used for
treatment for thyrotoxicosis and differentiated thyroid cancer whole body metastatic scanning
What hormones does the thyroid produce?
triiodothyronine (T3) and thyroxine(T4).
How many whole body images are taken
two! one at 24 and one at 48 hours
Sublingual glands located
under the tongue anterior and anterior tothe submandibular glands and lateral to the tongue
Submandibular glands are located
under the tongue near the posterior aspect of the floor of the mouth.
The dose for a patient receiveing I-131 therapy is
up to 200 mCi
Dacroscintigraphy Dynamic imaging
use 10 s/frame for 1-2 min followed by 1 min/frame for 15-20 min.
Patients with iodine allergy
use perchlorate.
Fluorine-18 FDG:
used to determine extent of disease and response to therapy. The degree of FDG uptake in metastatic thyroid carcinoma has prognostic significance.
High TSH levels are
used to stimulate both normal and differentiated thyroid carcinoma to increase its uptake of iodine and stimulate secretion of thyroglobulin
Signature of Authorized physician
user specified to administer therapeutic radionuclide doses in excess of 30 mCi total dose as per hospital and NRC reg 10 CFR 35.300, date and time
A euthyroid patient
usually reaches a plateau at 18-20 hours and is stable for several hours afterward
Follicular carcinoma is more likely to spread by
vascular invasion
Parathyroid adenomas are usually
well encapsulated, benign lesions. They are very small, with ectopic lesions being larger.
Structural disorders can occur
with or without clinical alterations due to thyroid hormone over or under production
Goiters can be present
with or without nodules
When should trapping of pertechnetate occur for a salivary gland study
within 1 min of intravenous injection in normal glands.
Papillary carcinoma is more common in
women and presents in the 30-40 year age group
Does I-123 cross the placenta
yes
Does I-131 cross the placenta
yes
Make sure for uptake
you get the same geometry everytime counts are measured!
Decay equation
% uptake= (neck-thigh)/ ((standard counts time zero X Decay factor)-Background) X 100
Countable standard equation
% uptake= (neck-thigh)/ ((standard counts time zero)-Background) X 100
Inverse square law equation
(I1 d1)^2 = (I2d2)^2
The how to for Decay method
*Count pill at 25-30 cm away fro 60 seconds with the pill in Lucite neck phantom. *Use the same geometry as the patient each time counts are measured * tell the patient to not eat for a couple hours after pill is administered and to return in 6 hours * count the neck and background, which is on the thigh away from the bladder. *Thyroid should be shielded for background counts *repeat at 24 hours
Symptoms of hyperthyroidism are
*Increased appetite and food intake, but with a decrease in body weight. *Poor Sleep *Sweating *Muscle weakness and/or wasting *Gastrointestinal disturbances *Feeling of warmth *Increased sweating *Rapid pulse *Palpitations *Emotional outbursts *bulging eyes *finger clubbing *tremors
What is normally the treatment for thyroid storm
*PTU and Tapezole are usually prescribed in high doses to decrease thyroide hormone synthesis. *Beta Blockers for controlling the heart rate *steriods to support the circulation *aggressive therapy
Indications for RAI therapy are
*failed medical therapy or surgery *medical or surgical therapy are contraindicated
RAIU are useful for patients
*with hyperthyroidism in whome 131-Iodine therapy is indicated *in cases of organification defects and certain types of thyroiditis
Normal thyroid ranges
6 hours: 6-18% 24 hours 10-35%
99mTc-Pertechnetate half life is?
6.02 hours
How long should the patient be off of Steroids, Adrenal Cortical steroids
8 days
How long should the patient be off of Iodinated contrast (CT, Myelograms, Cardiac cath.)
8 weeks and greater
What is the half life of I-131
8.1 days
Papillary and Follicular carcinoma account for what % of the thyroid cancer cases
95%
extra-thyroidal fraction
95%
Other way of dual isotope imaging
Can also use 123-Iodine with Sestamibi or Thallium, but must always subtract. The patient must remain still for a long length of time. The down-scatter from the higher energy radionuclide to the lower energy window. The time for iodine-123 localization is a disadvantage. The images are both normalized to each other (the counts per pixel are the same in the thyroid images to each other).
