ARDMS Updated SPI Exam Questions and Answers by aniyah

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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Color Doppler imaging is most effective when the angle between the ultrasound beam and the flow of blood is small.

At an angle of 88 degrees, the flow of blood is nearly perpendicular to the ultrasound beam.

When the angle is close to 90 degrees, the Doppler shift (frequency change) approaches zero, resulting in little to no color being visualized on the Doppler image.

Thus, to obtain a color signal, the angle should be optimized to be as close to 0 degrees as possible, with 60 degrees being the practical limit for accurate Doppler measurements.References:

ARDMS Sonography Principles and Instrumentation guidelines on Doppler angle and its effect on Doppler imaging.

Comprehensive and Detailed Explanation From Exact Extract:

Axial resolution is determined by the spatial pulse length (SPL). A longer SPL means that structures closer together along the beam axis are more likely to overlap in the returning echoes, degrading axial resolution.

According to sonography instrumentation reference:

“Axial resolution is inversely related to spatial pulse length. Increasing SPL worsens the ability to distinguish closely spaced structures along the beam axis.”

Therefore, the correct answer is B: Degraded axial resolution.

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Based on the table in this image, what is the sensitivity?

A white square with black numbers and a white square with black numbers Description automatically generated

A. 32/33

B. 32/35

C. 45/46

D. 45/48

Answer: B

Comprehensive and Detailed Explanation From Exact Extract:

Sensitivity measures the test's ability to correctly identify true positives. It is calculated using the formula:

Sensitivity = True Positives / (True Positives + False Negatives)

From the table:

True Positives (TP) = 32 (Noninvasive test positive & Gold Standard positive)

False Negatives (FN) = 3 (Noninvasive test negative but Gold Standard positive)

Thus:

Sensitivity = 32 / (32 + 3)

Sensitivity = 32 / 35

According to sonography instrumentation reference:

“Sensitivity represents the proportion of actual positive cases correctly identified by the test.”

Therefore, the correct answer is B: 32/35.

At what Doppler angle to flow is the maximum Doppler shift frequency acquired?

A. 90 degrees

B. 60 degrees

C. 30 degrees

D. 0 degrees

Answer: D

Comprehensive and Detailed Explanation From Exact Extract:

The Doppler equation shows that the frequency shift is proportional to the cosine of the Doppler angle. The maximum value of cosine (cos 0° = 1) occurs at 0 degrees — meaning the beam is parallel to flow. At this angle, the full velocity component is measured.

According to sonography instrumentation reference:

“The maximum Doppler shift is obtained when the ultrasound beam is parallel (0 degrees) to blood flow.”

Therefore, the correct answer is D: 0 degrees.

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Comprehensive and Detailed Explanation From Exact Extract:

When evaluating high blood velocities, especially at angles closer to zero degrees (which produces maximum Doppler shifts), aliasing can easily occur because the Doppler frequency shift increases. To avoid aliasing, you must increase the Doppler scale (which increases the pulse repetition frequency, PRF) to accommodate these higher velocities.

According to sonography instrumentation references:

“The Doppler scale (PRF) must be increased when high velocities are anticipated to prevent aliasing, especially at optimal Doppler angles near zero degrees where maximum frequency shifts occur.”

Therefore, the correct answer is C: Increased Doppler scale settings.

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