PM&R: Ultrasound

Effect of high frequency vs low frequency transducers on image quality and tissue penetration depth

1. High frequency: Low penetration but great detail (surface images) 2. Low frequency: High penetration, lousy detail (deep structures)

"Reset" button to revert to standard view

2D Mode

B-mode is same as:

2D mode, greyscale mode

M-Mode

2D view used to delineate moving structures vs static structures. Moving: more granular while static are more straight lines. (2D image of movement on screen)

at what age does rtc tears become likely based on image studies? unilateral vs bilateral

60 unilateral, 68 bilateral

u/s csa measurements cutoffs for ulnar nerve enlarge at cubital tunnel

> 7.9mm^2 - 10mm^2. compare side to side too, greater than double is probably enlarged

mnemonic for first dorsal compartment wrist two tendons (dequervain's)

All Peanut Lovers (APL), Eat Peanut Butter (EPB)

Doppler, or pulsed wave doppler

Basically shows waveforms with ultrasound. Useful for seeing blood flow through vessels (doppler lower ext u/c for dvt, etc). Higher velocity, higher height of tracing

Metal vs wood on u/s appearance (in regard to foreign body removal)

Both hyperechoic, but metal has a reverberation artifact while wood does not (but both may have some sort of shadowing)

remember the elbow forearm "homebase" location

Brachialis is middle with brachiaradialis/radial n on one side, biceps tendon on top, and pronator teres with median nerve on other side

What's a partial tendon rupture look like on full ROM compared to complete tendon rupture?

Complete retracts (duh, cuz it's not attached), while partial will not retract

persistently retracted tendon is noted on ultrasonography when a joint is taken through a normal range of motion likely indicates:

Complete tendon tear

Convex transducer vs Phased array transducer vs linear probe and best one for MSK general

Convex transducer: "bubble shape", so edges of resolution aren't as good (scan lines at margins spread out a bit, almost like a goPro). Thus, need to focus at center. Then, Phased Array transducer also spreads out at edges somewhat too, also need to focus more. But, it's center is even more focused then convex transducer, allows better narrow window of view (between ribs, etc). But, have a more constricted viewing angle then the Convex Then Linear probe: Sound waves equal all the way across, even margins are same resolution. Usually high frequency, good for near-field visualization (i.e. MSK!)

Possible ultrasound findings for diagnosing cubitual tunnel syndrome with ulnar nerve?

Cross-sectional area 10mm or larger. http://www.archives-pmr.org/article/S0003-9993(17)31071-7/abstract Ulnar Nerve Cross-sectional Area for the Diagnosis of Cubital Tunnel Syndrome: A Meta-analysis of Ultrasonographic Measurements

Gain vs Depth

Depth changes how deep signal is going and just how much is shown on screen (decrease it to "focus" on more peripheral structures). Gain adjusts echogenicity (brightness)-goal is to adjust to get uniform gain throughout image (so not half screen black/white). Both basically are ways to play with image on screen and get the optimal view

Hypoechoic, hyperechoic, anechoic and examples

Echogenicity refers to brightness of tissue. Hyper is more bright than surrounding tissue, hypo less. Hyper: bone (more dense), hypo: water, blood, urine. anechoic no echoes

Muscle appearance on u/s

Fairly hypoechoic, punctuated by hyperechoic striae; separated by hyperechoic fascia planes

Anisotropy

False hypoechogenicity resulting from oblique ultrasound beam

Nerve appearance on ultrasound?

Fascicular appearance in which the individual nerve fascicles are hypoechoic, surrounded by hyperechoic connective tissue epineurium, often "honeycomb" like

Effect of gas on u/s?

Gas is the enemy of u/s. Scatters ultrasounds waves, makes visualization difficulty

Describe attenuation, high vs low attenuation tissue and usefulness

Gradual weakening of sound as it travels into and then out of body. If sound hit a high "attenuating tissue"(highly dense tissues), echoes behind it are less, and thus a shadow (acoustic shadow) presents behind it. Vice versa, if it hits low attenuation tissue (such as fluid, water, urine), may highlight and increase echoes behind it, creating a window to view structures ("acoustic window" to view structures behind it)

Ideal u/s probe for eval soft tissue and other subsurface structures, as in MSK?

High-frequency linear probe

Appearance of nerve

Honey comb

Muscle injury appearance (echogenicity) on U/S?

Hyperechoic

Infection appearance in soft tissue on u/s?

Hyperechoic, may be little dots/spots of hyperechoic. If near bone, suspect osteomyelitis

Appearance of diabetic infarcted tissue and/or myositis tissue on u/s?

Hyperechoic, often with increased blood flow / hyperemia to region on doppler

Hematoma appearance on u/s?

Hypoechoic near muscle, or within, etc

Cartilage appearance on ultrasound?

Hypoechoic relative to bone and most other tissues

Mirror Edge Artifact

If a structure is located close to a highly reflective interface (such as the diaphragm), it is detected and displayed in its normal position. However, the strong reflector causes additional sound waves to bend towards the neighboring anatomy, from where they are bounced back towards the strong reflector and return to the transducer. These sound waves have a longer travel time and are perceived as an additional anatomic structure. The image is duplicated on the other side of the strong reflector (see figure 7).

Lot's of anechoic substances surrounding tendon?: Suspect-

Likely fluid, representing inflammation, thickening of tendon sheath in tenosynovitis picture

Best way to scan joints with u/s? (probe positioning)

Linear transducer in LONG axis of joint (so covers both sides of it for seagull sign

How to differentiate medial vs laterl epidonylosis on u/s? (expected changes on u/s)

Look at both medial and lateral tendon surfaces, the one involved tends to be (flexor, extensor attachments) would be thicker, more hyperechoic, possibly more fluid compared to opposite side

Give example of low attenuation structure? Of High?

Low: Urine High: Bone

Lymph nodes vs abscess on u/s

Lymph nodes are hyperemic, unlike abscess. Otherwise similar in apperance

One key difference in U/S findings of OA vs RA is?

OA usually has no increased hyperemia (blood flow on Doppler) at joints while RA often does

Ganglion cyst appearance on ultrasound? Fluid characteristics?

Often MULTILOCULAR appearance of a cyst is specific to both ganglion cysts and fibrocartilage cysts (parameniscal and paralabral); the location of the multilocular cyst assists in this diagnosis. If in contact with fibrocartilage, then parameniscal or paralabral cyst is likely. Fluid is often extremely thick, so aspiration requires larger needle

Way to dx carpal tunnel syndrome on ultrasound?

One study has calculated that a 2 mm ² difference in nerve cross-section (area) between the level of the pronator quadratus and the carpal tunnel has a 99% sensitivity and 100% specificity for CTS (http://www.ajronline.org/doi/10.2214/AJR.10.4817) > 10mm^2 (some use 9) -[Recent review: direct tracing, at site of maximal enlargement or at level of pisiform bone]

Penetration vs Resolution modes

Penetration deepest, but lowest frequency and lousy detail. Resolution mode is highest frequency and most detail, but lousy for deep penetrating body tissues. Finally, Gen mode is right in the middle between penetration and resolution, with middle frequency.

Is there evidence suggesting U/S is an accurate way to detect fractures, including rib fractures? Can you use to reduce fractures?

Per Sonosim module, yes (Griffith JF, Rainer TH, Ching ASC, et al. Sonography compared with radiography in revealing acute rib fractures. AJR AM J Roentgenol 1999 Dec;173(6):1603-1609.) Also may use to reduce fractures. Long axis view preferred

Power Doppler vs Color Doppler

Power:Single color, more sensitive, good for small objects/vessels/MSK. May have flash artifact Color:2 colors, angle dependent, detects directional movement, more specific

Which mode of U/S may have some safety concerns?

Pulsed-wave Doppler and Continuous Wave Doppler (others are pretty safe)--primarily in infants. If needed, must follow: TI ≤ 1.0 Exposure time ≈ 5 to 10 min

When imaging the patient in a sagittal plane, the patient's feet are oriented toward: LEFT or RIGHT of screen?

RIGHT

Reverberation Artifacts

Recurrent bright arcs at equidistant intervals; artifact caused by curved-array or phased-array transducers with multiple reflections of waves

Color flow doppler: Red vs blue

Red: Flow towards transducer, blue is away from

Tendon within a tendon seen on supraspinatus imaging maybe:

Rotator Cable. Attaches at three points to humerus (anterior insertion on superior facet less tubercle, intermediate intersion on greater tubercle, posterior insertion on inferior edge of infraspinatus tendon). Tight connection with rotator cuff tendons, Acts as a suspension bridge to tramit load to the cable from RTC, then to the humerus, can allow for shoulder ROM/strength even in setting of full-thickness RTC tears.

Lateral cystic artifact:

Same as edge artifact, results from sound waves refracted from objects

How to spot Morton's Neuroma on u/s? (and what it is)

Scan bottom of foot. squeeze toes together, watch neuroma pop out. https://www.youtube.com/watch?v=pPKMCsWF-l0 - benign tumor of a nerve. Morton's neuroma is not actually a tumor, but a thickening of the tissue that surrounds the digital nerve leading to the toes.

Medial meniscal extrustion significant size on weight bearing under ultrasound?

Several studies note medial meniscal extrusion (MME) that is 3 mm or greater (defined as radial displacement beyond medial edge of tibiofemoral joint line) is significant, represents internal derangement, correlated with DJD progression. May scan while weight bearing as well for more function eval

Edge artifact is from: _ _

Sound refraction

Describe refraction of u/s waves

Sound traveling between different mediums, speed changes, and alters image/creates artifact. Somewhat similar to light passing through water/air. Causes Edge Artifact

Options to protect patient in MSK u/s exam?

Standoff pad, water as transducer window (don't even touch the patient), local analgesics (as it's close to skin with high frequency)

What area is typical injection target on ultrasound knee injection?

Suprapatellar pouch/bursa. Connects with knee joint

Heel-toe maneuver. vs Toggle maneuver with U/S:

The term heel-toe is used when the transducer is rocked or angled along the long axis of the transducer The term toggle is used when the transducer is angled from side to side With both the heel-toe and toggle maneuvers, the transducer is not moved from its location, but rather the transducer is angled. ( http://goo.gl/6ZwxxW A= Heel toe B=Toggle)

Signs of tendon pathology on U/S; ways to test

Thickening (compared to other side), decreased echogenicity (more fluid present due to inflammation), more vascularity on Doppler (from inflammation), sometime calcifications (chronic damage); Discontinuity of fibers (maybe a tear?); make sure to RANGE the joint to look at tendon better

Standard orientation of transducers (dot on probe)

Towards head (saggital view) or patient's right ( transverse view)--Always! Patient's feet on screen (caudal) will be on right when transducer probe is saggital view

Inflamed tendons tend to have a thicker appearance relative to the unaffected side: T/F

True

T or F: U/S effective means for localization of foreign bodies for removal, and can pick up objects missed by Xray

True; such as wooden splinters. Offers more 3d view and better localization for more accurate and less invasive object removal

piezoelectric effect of the ultrasound transducer crystal:

Turns electrical signal into ultrasonic energy and vice versa

Needle pivot technique to improve visualization

Twisting the needle around its axis can improve visualization as the needle tip echogeniety changes

Seagull sign on u/s

Two joints coming together, looks look seagull wings (kid drawing)

What has better resolution, u/s or mri

U/s! Can zoom down to 150microns while MRI only to 450 microns

Describe ulnar sublaxation and U/S view

Ulnar nerve may sublax on elbow flexion, rolling out of space it sits and going medially over medial epicodyle. Can visualize through u/s with going from extension to flexion. See here: https://youtu.be/np64d7C55qE Also, medial head of triceps may sublax at same time, both can lead to snapping: https://youtu.be/bybBQoQJ-B4

What is superior/cephalic and inferior/caudal on joint u/s imaging on screen?

Use long axis of joint, notch towards head, resulting in (onscreen): Left of screen: superior/cephalic end and right of screen inferior/caudal end

Technique to image very superficial structures, such as in finger/hand? Or for very sensitive/painful skin?

Use standoff pad or a water bath

Define "sonopalpation"

Using the transducer, while imaging, to actively push on structures to see if they cause pain when compressed on u/s

T/F: U/S is good way to locate joint effusions

YES! True! Look for hypoechoic/anechoic substance at seagull sign joints (may be compressible), very good tool for this, good tool for aspiration as well

Persistently retracted tendon is noted on ultrasonography when a joint is taken through a normal range of motion, this suggests a:

complete tendon tear (partial tears do no retract)

Anisotropy :

false hypoechogenicity resulting from oblique ultrasound beam, often on something very dense, like a tendon. Must account for this when looking at tendons. Must re-orient the beam to fix this, or might think a tendon is damaged when it really isn't. Basically, muscles and tendons changing to more hypoechoic based on not perfectly perpendicular probe

fascicular vs fibrillar appearance typically seen in which structures?

fascicular: Nerve fibrillar: tendons

how to bring out effusions in GHJ when doing ultrasound?

have patient EXTERNALLY rotate the shoulder

Lipoma appearance on U/S?

homogeneous, oval, isoechoic to minimally hyperechoic mass, with little or no flow on color or power Doppler imaging, that is soft and pliable with transducer pressure (MRI is preferred analysis method though if questions)

Tendons appear very hyperechoic or hypoechoic on ultrasound imaging.

hyperechoic

Epidermis, hypodermis, subq fascia shows on u/s as?

hyperechoic lines (less so than bone)

Describe tendon characteristics on u/s and pattern

hyperechoic parallel fibrillar pattern when viewed in a longitudinal plane

hyaline cartilage vs fibrocartilage appearance and examples of the latter:

hypoechoic and fibro (meniscus, labrum ) is hyperchoic

describe A1 pulley appearance on ultrasound

hypoechoic ring at level of mcp joint that is more pronounced/delineated hypoechoic than above or below regions (subtle)

findings suggestive of cellulitis on u/s?

islands of hyperechogenicity are referred to as cobblestoning of cellulitis; also can be seen with soft tissue edema. Use to differentiate from abscess (big collection hypoechoic substance, compressible with swirling of debris)

Stylet technique for visualizing needle during injection?

piston/move the stylet within the needle to help bring it into view

posterior acoustic enhancement:

refers to the increased echoes deep to structures that transmit sound exceptionally well. This is characteristic of fluid filled structures such as cysts, the urinary bladder and the gallbladder.

Edge artifact cause

refraction of u/s sound waves

most likely area in shoulder of RTC tear and term for it?

rotator crescent - infra and Supra junction, 15mm posterior to biceps tendon

Define "sonopalpation"

tenosynovitis (normally shouldn't have fluid around it)