MSK US Physics Flashcards
What is Fridberg’s infarction?
A flattened metatarsal head, cortical changes, and loss of cartilage mostly involving the second MTP joint may indicate avascular necrosis (Freidberg’s infarction). Joint fluid and synovial changes with positive Copler Doppler may be more indicative of spetic joint or RA.
A patient c/o chronic forefoot pain localized over the 2nd and 3rd metatarsophalangeal joints. On US, a flattened metatarsal head, periosteum changes and loss of articular cartilage is seen. What is the most likely diagnosis: A. Septic Joint
B. Mortons Neuroma, C. A normal Finding, D. Freidberg’s infarction or E. Rheumatoin Arthitis.
D. Freidbergs infarcation or avasucular necrosis
You are performing an US guided obturator nerve block on an individual with a large body habitus. Altering which ultrasound parameter will be best to improve image resolution and reduce noise? A. Increasing field view, B, Turning on Tissue harmonic imaging, C. Increasing transducer frequency, D. Moving the focal zone more superficial to widen beam width or E. Decreasing wavelength
B-Turning on Tissue Harmonic imaging
What is Tissue harmonic imaging and what does it do?
Tissue Harmonic imaging reduces noise by removing extra artifacts. This occurs by emitting and listening at different frequencies which improves image quality for deeper structures. Fig. 2: Tissue harmonic images are obtained by collecting harmonic signals that are tissue generated and filtering out the fundamental echo signals that are transducer generated resulting in crisper images. In an ultrasound context, tissue harmonic imaging is a signal processing technique also termed native harmonic imaging. An ultrasound beam insonates body tissues and generates such harmonic waves from nonlinear distortion during the transmit phase of the pulse-echo cycle. Harmonics are multiples of the fundamental frequency, hence transmitting a band of frequencies centered at 3 MHz will result in the production of harmonic frequency bands centered at 6 MHz, 9 MHz, 12 MHz, etc.
When imaging a deeper structure, more listening time is required for sound waves to reach the area of interest and return information to the transducer. This is an example of what is most likely concept. A. Dynamic imaging, B. Tissue Harmonics, C. Spatial pulse length, D. Duty Factor or E. Pusle repetition frequency
D. Duty Factor
What is the duty factor?
Is the percentage of time the transducer emits sound waves and the percentage of time the transducer is silent when listening for the returning waves. Diagnostic ultrasound duty factor is already low (1%) and is even lower when scanning deeper structures.
The following images represent a change in which most likely ultrasound parameter? A. Time gain compensation, B. Dynamic range, C. Tissue Harmonics, D. Depth and E. Resolution.
A
Increasing the brightness or intensity of the perceived signal is known as what?
Time gain control. This differs from harmonic imaging and dynamic range as an increase in gain causes noise artifacts in areas that are anecohic.
What is a wall filter?
Using a wall filter can help filter out high and low frequencies from Doppler signals. Typically wall filters are used to get rid of low frequencies from arterial wall movement which may add noise to the spectral doppler waveform
The following images represent a change in which most likely ultrasound parameter? A. Time gain compensation, B. Dynamic Range, C. Harmonics, D. Focal zone and E. Depth
B
What parameter is it when you can adjust the overall shades of gray?
Dynamic Range. This determines how dark or light you prefer an image to be, and an increase in the dynamic range has less contrast but smoother images. A decrease in dynamic range produces more black and white echos therefore creating more contrast and defined borders
Meralgia Paresthtica-what is it?
Involves entrapment of the lateral femoral cutaneous nerve which can be found just medial to the the ASIS
A patient with symptoms of meralgia paresthetica. Which landmark is most important to identify for an ultrasound-guided injection? A. Pubic symphysis B. Femoral Arther, C. Inferior epigastric artery, Femoral head, and neck junction, and E. ASIS
E. ASIS
The pes anserine tendon is conjoined of which structures? (think medial)
Sartorius, gracilis and semitendinosus (picture wound be handy)
What is a Pellegrini-Stieda lesion
small ossifications at the medial femoral condyle where the MXL inserts. This specifically occurs following an MCL injury, whereas other conditions such as heterotrophic ossification, myositis ossificans, and chondrocalcinosis are not specific to MCL tearing
Which structures are located in the second dorsal compartment of the wrist? A. APB/ERB B. EPL/ECRB, C. EPL/ECRL, D. APL/EPB, E. ECRL/ECRB
E. ECRL/ECRB (nice to have picture of the compartments
When adjusting the dynamic range on US, which of the following is false? A. An increase in dynamic range creates a wider range of gray shades, therefore, creating less contrast between objects, B. A decrease in dynamic range creates more black and white shades, therefore, creating more contrast between object C. An increase in dynamic range creates more defined borders by increasing black and white shades, D. A decrease in dynamic range creates more defined borders by increasing black and white shades, and E. An increase in dynamic range creates a wider range of black and white shades, therefore, improving contrast between subjects.
E. An increase in dynamic range creates a wider range of black and white shades, therefore, improving contrast between objects
What is a Morel Lavallee lesion?
A Morel-Lavallee Lesion (MLL) is a closed traumatic soft tissue degloving injury characterized by separation of the dermis from the underlying fascia due to a shearing force.
Diagnosis requires high a index of suspicion with presence of an area of ecchymosis, swelling, fluctuance and skin hypermobility in the polytrauma patient with underlying fractures.
Treatment is generally operative irrigation and debridement for most lesions given the proximity to planned surgical incisions and increased risk of infection.
Incidence
present in up to 8% of acetabulum fractures
Anatomic location
most often along proximal lateral thigh, in the peritrochanteric region
to a lesser extent gluteal, lumbosacral, and abdominal areas
due to hypermobility of skin in these regions
Which us term best describes the distance one cycle has traveled: A. Perior, B. Frequency, C. Wavelength, D. Propagation speed, E. Intensity
C. Wavelength. Frequency is the term used to describe the number of cycles in one second, period is the time of one complete cycle, and wavelength is the distance of on complete cycle (pic?) Propagation speed is the velocity of sound waves through time and space and intensity is the rate of energy through a substance
Which of the following parameters best process information received from sampling an area of high blood flow? A. Pulse repetition frequency B. Beam width C. Power Doppler D. Gain E. Wavelength.
A. Pulse repetition frequency. PRF is a major parameter in determining the sample time from blood flow, whether high or low velocity. Adjusting the PRF allows sufficient time for the signal to return to the transducer and accurately be displayed on the screen.
Describe Pulse repetition frequency
The number of pulses created in each second. (Hz). and created by sound sources, not by the medium through which the sound travels. PRF is unrelated to frequency. It is related only to a depth of view and can be changed by adjusting the depth of view of a scan. This is because the unit will consider the low-amplitude velocities to be originating from the surrounding soft tissues and thus representative of noise. In most Doppler US systems, the PRF or velocity scale control and the wall filter control are linked. For example, when the velocity scale or PRF is increased, the wall filter also will increase to the high setting, and, therefore, a higher range of relatively low frequency shifts will be filtered out and not displayed on the color or spectral image. To improve flow visualization, the examiner should decrease the velocity scale range or PRF (Movie 4). Understanding this phenomenon is essential during attempts to detect flow in, for example, a vein suspected of having a bland or tumor thrombus or in a suspicious mass. In such instances, the velocity scale must be decreased to as low as necessary (?5–10 PRF) to have confidence that the flow within a lesion is truly absent (Movie 5).
While scanning the posterior lower leg, a Color doppler is used to determine whether an anechoic space is a vessel or cyst. All of the following us parameters need to be increased to detect high-velocity flow, except A. Gain, B. Wall filter C. Pulse repetition frequency D All of the above, E. None of the above.
D. All of the above. All of the following parameters will nee to increase to detect the highest amount of blood flow to help distinguish a vessel from a cyst which typically does not contain blood flow.
Blooming artifact is seen in US. Changes in which parameter will optimize the visualization of vascular flow? A. Decrease gain, B. Increase wall filter, C. Increase velocity scale D. Increase angle of insonation E. All of the above
E. All of the above. All of the following parameters limit the amount of signal perceived outside of a vessel. Excess signals or “bleed” outside a vessel wall can give a misrepresentation of blood flow within the area.
US guided hydrodissection is considered for a patient with heel pain. What is the most likely diagnosis. A. Plantar fasciitis, B. Plantar Heel spur, C. Calcaneous stress fracture, D. Baxter’s neuropathy and E. Achilles tendinopathy
D. Baxters Neuropathy: Hydrodissection is a procedure to improve peripheral nerve mobility. Baxters neuropathy is the only diagnosis in which dydrodissection may help
