ARDMS Sonography Principles and Instrumentation SPI Exam Questions

Answer : B

Comprehensive and Detailed Explanation From Exact Extract:

When the ultrasound beam travels through a structure that attenuates less than surrounding tissues, more energy reaches structures located deeper. This results in stronger echo signals from those deeper structures, which is visualized as a brightening or enhancement distal to the structure. This is referred to as acoustic enhancement or posterior enhancement.

Official sonography instrumentation reference states:

''Enhancement occurs as a result of reduced attenuation of the sound beam as it passes through fluid-filled or weakly attenuating structures, causing reflectors distal to the structure to appear more echogenic than normal.''

Therefore, the correct answer is B: Enhancement.

Answer : C

Temporal resolution refers to the ability of the ultrasound system to distinguish events occurring closely in time. In color flow imaging, temporal resolution is affected by the frame rate, which can be increased by decreasing the width of the color field of view. This is because a narrower color field requires fewer scan lines to be processed, allowing for more frames to be captured per second.

ARDMS Sonography Principles and Instrumentation guidelines

Edelman, S. K. (2017). Understanding Ultrasound Physics.

Answer : A

The duty factor is the fraction of time that the ultrasound system is actively transmitting a signal. Continuous wave (CW) Doppler has the highest duty factor because it continuously transmits and receives ultrasound waves. Unlike pulsed wave Doppler, which alternates between sending and receiving signals, CW Doppler does not have a listening period, resulting in a duty factor of nearly 100%. Therefore, CW Doppler has the highest duty factor among the modes listed.

ARDMS Sonography Principles & Instrumentation Guidelines

Hedrick WR, Hykes DL, Starchman DE. Ultrasound Physics and Instrumentation. 4th ed. Philadelphia, PA: Elsevier Saunders; 2005.

Answer : C

Comprehensive and Detailed Explanation From Exact Extract:

Low PRF reduces the Nyquist limit, making the system more susceptible to aliasing when Doppler shift frequencies exceed this limit.

Principles and Instrumentation state:

'Aliasing occurs when Doppler shifts exceed half the PRF (Nyquist limit). Lowering PRF increases aliasing susceptibility.'

Spectral broadening (A) results from turbulence or poor angle.

Range ambiguity (B) occurs at high PRF.

Dropout (D) refers to signal loss, not aliasing.

Therefore, the correct answer is C: Aliasing.

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Answer : D

Comprehensive and Detailed Explanation From Exact Extract:

The wall filter in Doppler ultrasound is designed to eliminate low-frequency signals, typically associated with motion artifacts such as vessel wall or tissue motion. These low-frequency signals are not part of the desired blood flow signal and can interfere with accurate Doppler display.

When the wall filter setting is increased, it removes these low-frequency signals from the Doppler spectrum. However, increasing the wall filter too much can also eliminate true low-velocity flow information, leading to a loss of clinically relevant data.

This principle is described in official sonography Principles and Instrumentation references:

'Increasing the wall filter will reduce the display of low-frequency Doppler shifts, which are typically associated with slow-moving structures. These low-frequency signals can represent either slow blood flow or tissue motion artifacts.'

Therefore, the correct answer is D: Reduced display of low-frequency shifts.

Answer : C

To avoid exceeding the Nyquist limit and prevent aliasing in Doppler ultrasound, the pulse repetition frequency (PRF) should be increased. The Nyquist limit is half of the PRF, so by increasing the PRF, the Nyquist limit is raised, allowing the system to accurately measure higher velocities without encountering aliasing artifacts. Reference:

ARDMS Sonography Principles and Instrumentation guidelines

Zwiebel, W. J., & Pellerito, J. S. (2017). Introduction to Vascular Ultrasonography. Elsevier.

Answer : A

Comprehensive and Detailed Explanation From Exact Extract:

Spatial compounding uses multiple scan angles to create an image. By combining information from different angles, it can reduce shadowing artifacts caused by highly attenuating structures.

According to sonography instrumentation reference:

''Spatial compounding reduces artifacts such as posterior shadowing by averaging images acquired from multiple insonation angles.''

Therefore, the correct answer is A: Increasing spatial compounding.

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