Free ARDMS SPI Practice Exam with Questions & Answers | Set: 4

Comprehensive and Detailed Explanation From Exact Extract:

Color Doppler detects flow based on the Doppler shift, which is dependent on the cosine of the angle between the ultrasound beam and the direction of blood flow. At 90 degrees, the cosine value is zero, resulting in no Doppler shift and therefore no detectable color flow signal.

According to sonography instrumentation reference:

“When the insonation angle is 90 degrees, the Doppler frequency shift is zero because the cosine of 90 degrees equals zero. As a result, no flow is displayed.”

Therefore, the correct answer is D: 90 degrees.

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Comprehensive and Detailed Explanation From Exact Extract:

A weakly attenuating structure allows ultrasound waves to pass through with minimal loss of energy. Because of this, structures located posterior to the weakly attenuating region appear brighter than expected — this is known as distal (posterior) enhancement. This artifact is most commonly observed when scanning fluid-filled structures such as cysts, the bladder, or the gallbladder.

Official sonography instrumentation reference states:

“When sound waves encounter a structure that attenuates sound minimally (low attenuation), more sound energy reaches deeper tissues. This results in increased echo amplitude from structures located distal to the weak attenuating structure, creating the appearance of distal enhancement.”

Therefore, the correct answer is D: Distal enhancement.

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Comprehensive and Detailed Explanation From Exact Extract:

Overall gain amplifies the strength of all returning echoes equally, regardless of depth. It does not affect the transmitted pulse or selectively compensate for attenuation; it simply amplifies received signals uniformly.

According to sonography instrumentation reference:

“Overall gain controls the amplification of all returning echoes across the entire image, increasing brightness uniformly at all depths.”

Therefore, the correct answer is B: Amplification of signals from all depths.

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Aliasing in pulsed-wave Doppler occurs when the sampled Doppler frequency exceeds the Nyquist limit, which is half of the pulse repetition frequency (PRF). This results in an incorrect representation of the blood flow velocities, causing the waveform to wrap around and appear on the opposite side of the baseline. To correct aliasing, the PRF should be increased, which raises the Nyquist limit and allows for accurate measurement of higher velocities without aliasing. Increasing the PRF effectively reduces the likelihood of aliasing artifacts in the Doppler signal.

American Registry for Diagnostic Medical Sonography (ARDMS). Sonography Principles and Instrumentation (SPI) Examination Review Guide.

In the tissue-mimicking phantom image, Option D (blue box) is used to evaluate transverse distance measurement accuracy. Phantoms are used to simulate human tissue and provide a standardized way to test the accuracy and precision of ultrasound machines. Transverse distance measurement accuracy is assessed by measuring known distances between targets in the phantom. The blue box (Option D) typically contains targets positioned to specifically test the accuracy of transverse measurements, ensuring that the ultrasound system provides reliable and precise distance readings.

References

ARDMS Sonography Principles and Instrumentation (SPI) Exam Study Guide

"Quality Assurance for Ultrasound Imaging Systems" by AAPM (American Association of Physicists in Medicine)

Attenuation refers to the reduction in the intensity of the ultrasound beam as it travels through tissue. Higher frequency ultrasound beams experience more attenuation because they are absorbed and scattered more than lower frequency beams. This is due to the fact that higher frequency waves have shorter wavelengths and interact more with the small particles in tissues, causing greater energy loss.

Enhancement artifact occurs when an anechoic (or low-attenuation) structure, such as a cyst or fluid-filled structure, allows the ultrasound beam to pass through it with minimal attenuation. As a result, the tissues located distal to this anechoic structure appear brighter (increased echo amplitude) on the ultrasound image because the sound waves are less attenuated by the anechoic structure, leading to higher intensity echoes returning from the distal tissue. This increased brightness beyond the anechoic area is known as enhancement.

ARDMS Sonography Principles and Instrumentation guidelines

Kremkau, F. W. (2015). Diagnostic Ultrasound: Principles and Instruments. Elsevier.

Comprehensive and Detailed Explanation From Exact Extract:

In pulsed-wave transducers, the thickness of the piezoelectric element primarily determines the fundamental operating frequency. Thinner elements produce higher frequencies, while thicker elements produce lower frequencies.

According to sonography instrumentation reference:

“The operating frequency of a pulsed-wave transducer is primarily determined by the thickness of the piezoelectric crystal. Thinner crystals vibrate at higher frequencies.”

Therefore, the correct answer is A: Element thickness.

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Comprehensive and Detailed Explanation From Exact Extract:

Speckle is a form of acoustic noise caused by interference of scattered echoes. Spatial compounding acquires multiple images from different angles and combines them to reduce speckle, enhance tissue texture, and improve visualization of structures that may otherwise be obscured by attenuation or artifact. The Principles and Instrumentation documentation states:

"Spatial compounding averages frames obtained at varying insonation angles. This reduces speckle artifact, smooths tissue texture, and improves visibility of specular reflectors and deeper structures."

Therefore, the correct answer is D: Spatial compounding.

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M-mode (Motion mode) is used in ultrasound to measure and display the movement of structures over time.

This mode is particularly useful in cardiac imaging to assess the motion of heart walls and valves.

M-mode provides a one-dimensional view of the motion of tissues and is often used in conjunction with 2D imaging for a comprehensive assessment.

It is essential in evaluating the dynamic function of organs, especially in cardiology, where precise measurements of cardiac structures' movement are crucial.References:

ARDMS Sonography Principles and Instrumentation guidelines on modes of ultrasound imaging and their clinical applications.