, Question 1
A 5 MHz transducer is replaced with a 2.5 MHz transducer while imaging the
same tissue at the same depth. Which statement best describes the effect on
spatial pulse length and axial resolution?
A. Spatial pulse length doubles, and axial resolution degrades by a factor
of two.
B. Spatial pulse length halves, and axial resolution improves by a factor
of two.
C. Spatial pulse length is unchanged because wavelength is independent
of frequency.
D. Spatial pulse length quadruples, and axial resolution degrades by a
factor of four.
Correct Answer: A - Spatial pulse length doubles, and axial
resolution degrades by a factor of two.
RATIONALE
Spatial pulse length equals the number of cycles in the pulse times
wavelength; at half the frequency, wavelength doubles, so SPL
doubles and axial resolution (SPL/2) degrades proportionally. Options
B and D misapply the inverse relationship, and C incorrectly claims
wavelength is frequency-independent.
Question 2
During a hepatoportal Doppler study, the spectral waveform shows continuous
hepatofugal flow in the main portal vein with a dampened, monophasic hepatic
vein tracing. Which hemodynamic alteration best explains this pattern?
A. Elevated right atrial pressure transmitted retrograde through the IVC
B. Increased sinusoidal resistance with portosystemic collateral
development
C. Reduced splanchnic arterial inflow causing portal venous hypotension
D. Acquired portal vein thrombosis with cavernous transformation
Page 2
,Correct Answer: B - Increased sinusoidal resistance with
portosystemic collateral development
RATIONALE
Hepatofugal portal flow with dampened hepatic vein phasicity reflects
increased intrahepatic sinusoidal resistance and portal hypertension
with collateral pathways. Elevated right atrial pressure would typically
produce pulsatile hepatic vein flow, while thrombosis would show
absent flow rather than reversal.
Question 3
Which of the following best explains why a sonographer should avoid using a
2D frame rate of 60 Hz when performing pulsed-wave Doppler of the left
ventricular outflow tract?
A. High frame rates increase temporal resolution but reduce Doppler
sensitivity due to decreased ensemble length.
B. High frame rates increase the Nyquist limit, causing aliasing of the
LVOT velocity.
C. High frame rates reduce spatial resolution, which is the primary
determinant of Doppler accuracy.
D. High frame rates increase thermal index but do not affect Doppler
spectral quality.
Correct Answer: A - High frame rates increase temporal
resolution but reduce Doppler sensitivity due to decreased
ensemble length.
RATIONALE
A high 2D frame rate shortens the time available for Doppler
ensembles, reducing the number of pulses per spectral line and thus
decreasing Doppler sensitivity and velocity resolution. Nyquist limit is
determined by pulse repetition frequency, not frame rate, and spatial
resolution is not the primary determinant of Doppler accuracy.
Page 3
, Question 4
A quality assurance phantom reveals that the measured axial resolution at 5 cm
depth is 1.2 mm, while the manufacturer specification is 0.8 mm. Which
parameter is most likely miscalibrated?
A. Transducer frequency selection
B. Time-gain compensation (TGC) slope
C. Acoustic power output
D. Dynamic range
Correct Answer: A - Transducer frequency selection
RATIONALE
Axial resolution is determined by spatial pulse length, which depends
on frequency and cycles per pulse; a discrepancy suggests the system
is not operating at the expected frequency. TGC and dynamic range
affect amplitude display, not axial resolution, and acoustic power does
not change SPL.
Question 5
Which of the following statements correctly describes the relationship between
the Doppler angle and the measured velocity when the angle exceeds 60
degrees?
A. The cosine of the angle decreases rapidly, causing a disproportionately
large velocity overestimation.
B. The cosine of the angle decreases rapidly, causing a disproportionately
large velocity underestimation.
C. The cosine of the angle increases, causing velocity underestimation.
D. The angle has no effect on velocity calculation if the angle is
corrected.
Correct Answer: B - The cosine of the angle decreases rapidly,
causing a disproportionately large velocity underestimation.
Page 4
A 5 MHz transducer is replaced with a 2.5 MHz transducer while imaging the
same tissue at the same depth. Which statement best describes the effect on
spatial pulse length and axial resolution?
A. Spatial pulse length doubles, and axial resolution degrades by a factor
of two.
B. Spatial pulse length halves, and axial resolution improves by a factor
of two.
C. Spatial pulse length is unchanged because wavelength is independent
of frequency.
D. Spatial pulse length quadruples, and axial resolution degrades by a
factor of four.
Correct Answer: A - Spatial pulse length doubles, and axial
resolution degrades by a factor of two.
RATIONALE
Spatial pulse length equals the number of cycles in the pulse times
wavelength; at half the frequency, wavelength doubles, so SPL
doubles and axial resolution (SPL/2) degrades proportionally. Options
B and D misapply the inverse relationship, and C incorrectly claims
wavelength is frequency-independent.
Question 2
During a hepatoportal Doppler study, the spectral waveform shows continuous
hepatofugal flow in the main portal vein with a dampened, monophasic hepatic
vein tracing. Which hemodynamic alteration best explains this pattern?
A. Elevated right atrial pressure transmitted retrograde through the IVC
B. Increased sinusoidal resistance with portosystemic collateral
development
C. Reduced splanchnic arterial inflow causing portal venous hypotension
D. Acquired portal vein thrombosis with cavernous transformation
Page 2
,Correct Answer: B - Increased sinusoidal resistance with
portosystemic collateral development
RATIONALE
Hepatofugal portal flow with dampened hepatic vein phasicity reflects
increased intrahepatic sinusoidal resistance and portal hypertension
with collateral pathways. Elevated right atrial pressure would typically
produce pulsatile hepatic vein flow, while thrombosis would show
absent flow rather than reversal.
Question 3
Which of the following best explains why a sonographer should avoid using a
2D frame rate of 60 Hz when performing pulsed-wave Doppler of the left
ventricular outflow tract?
A. High frame rates increase temporal resolution but reduce Doppler
sensitivity due to decreased ensemble length.
B. High frame rates increase the Nyquist limit, causing aliasing of the
LVOT velocity.
C. High frame rates reduce spatial resolution, which is the primary
determinant of Doppler accuracy.
D. High frame rates increase thermal index but do not affect Doppler
spectral quality.
Correct Answer: A - High frame rates increase temporal
resolution but reduce Doppler sensitivity due to decreased
ensemble length.
RATIONALE
A high 2D frame rate shortens the time available for Doppler
ensembles, reducing the number of pulses per spectral line and thus
decreasing Doppler sensitivity and velocity resolution. Nyquist limit is
determined by pulse repetition frequency, not frame rate, and spatial
resolution is not the primary determinant of Doppler accuracy.
Page 3
, Question 4
A quality assurance phantom reveals that the measured axial resolution at 5 cm
depth is 1.2 mm, while the manufacturer specification is 0.8 mm. Which
parameter is most likely miscalibrated?
A. Transducer frequency selection
B. Time-gain compensation (TGC) slope
C. Acoustic power output
D. Dynamic range
Correct Answer: A - Transducer frequency selection
RATIONALE
Axial resolution is determined by spatial pulse length, which depends
on frequency and cycles per pulse; a discrepancy suggests the system
is not operating at the expected frequency. TGC and dynamic range
affect amplitude display, not axial resolution, and acoustic power does
not change SPL.
Question 5
Which of the following statements correctly describes the relationship between
the Doppler angle and the measured velocity when the angle exceeds 60
degrees?
A. The cosine of the angle decreases rapidly, causing a disproportionately
large velocity overestimation.
B. The cosine of the angle decreases rapidly, causing a disproportionately
large velocity underestimation.
C. The cosine of the angle increases, causing velocity underestimation.
D. The angle has no effect on velocity calculation if the angle is
corrected.
Correct Answer: B - The cosine of the angle decreases rapidly,
causing a disproportionately large velocity underestimation.
Page 4
