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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