VT Diagnostic Imaging Techniques 3 — Questions and Answers
Question 1: On a spectral Doppler waveform, spectral broadening refers to:
- A wider systolic peak velocity
- Filling in of the spectral window due to turbulent or disturbed flow (Correct answer)
- Increased diastolic flow
- Monophasic waveform pattern
Correct answer: Filling in of the spectral window due to turbulent or disturbed flow
Spectral broadening occurs when a range of velocities are present simultaneously, filling the normally clear spectral window, indicating disturbed or turbulent flow.
Question 2: Which parameter best distinguishes a high-resistance arterial waveform from a low-resistance one?
- Peak systolic velocity
- End-diastolic velocity
- Acceleration time
- Pulsatility index (Correct answer)
Correct answer: Pulsatility index
Pulsatility index (PI = [PSV − EDV] / mean velocity) quantifies resistance; high PI indicates high resistance (e.g., fasting mesenteric arteries), low PI indicates low resistance (e.g., renal arteries).
Question 3: Which artifact causes a vessel to appear duplicated when imaging near a highly reflective surface such as the pleura?
- Shadowing
- Enhancement
- Mirror-image artifact (Correct answer)
- Side-lobe artifact
Correct answer: Mirror-image artifact
Mirror-image artifact occurs when the ultrasound beam reflects off a strong reflector (e.g., pleura), creating a duplicate image of the vessel on the other side of the reflector.
Question 4: Computed tomography angiography (CTA) of the lower extremities is performed with a scan direction that is:
- Caudal to cranial to follow contrast bolus (Correct answer)
- Cranial to caudal matching contrast progression
- Simultaneous bilateral acquisition
- Independent of contrast timing
Correct answer: Caudal to cranial to follow contrast bolus
For run-off CTA, scanning proceeds caudal to cranial (feet to pelvis) so the table moves counter to contrast flow, maximizing arterial enhancement throughout.
Question 5: In duplex imaging of the carotid artery, an increased internal carotid artery (ICA) to common carotid artery (CCA) PSV ratio above 2.0 suggests:
- Normal flow
- Less than 50% stenosis
- 50–69% stenosis
- 70% or greater stenosis (Correct answer)
Correct answer: 70% or greater stenosis
An ICA/CCA PSV ratio ≥ 2.0 correlates with hemodynamically significant stenosis of 70% or greater by the Society of Radiologists in Ultrasound consensus criteria.
Question 6: Which ultrasound technique enhances visualization of slow venous flow in the lower extremity by using microbubble contrast agents?
- Contrast-enhanced ultrasound (CEUS) (Correct answer)
- High-frequency linear imaging
- Tissue harmonic imaging
- Elastography
Correct answer: Contrast-enhanced ultrasound (CEUS)
CEUS uses intravascular microbubbles to dramatically improve the signal-to-noise ratio for detecting slow or low-volume venous flow.
Question 7: A 'tardus-parvus' waveform pattern downstream from a stenosis is characterized by:
- High PSV and sharp systolic upstroke
- Low PSV, prolonged acceleration time, and rounded systolic peak (Correct answer)
- Reversed diastolic flow
- Absent diastolic component
Correct answer: Low PSV, prolonged acceleration time, and rounded systolic peak
Tardus-parvus ('slow-small') describes the dampened waveform distal to a significant stenosis: low amplitude, prolonged systolic rise time, and loss of the sharp peak.
VT Diagnostic Imaging Techniques 3
On a spectral Doppler waveform, spectral broadening refers to: