VT Carotid & Vertebral Ultrasound 2 — Questions and Answers
Question 1: What PSV ratio (ICA/CCA) is used to classify a 70-99% ICA stenosis per the SRU consensus criteria?
- Greater than 2.0
- Greater than 4.0 (Correct answer)
- Greater than 3.0
- Greater than 1.5
Correct answer: Greater than 4.0
An ICA/CCA PSV ratio greater than 4.0 is used along with PSV >230 cm/s to classify 70-99% ICA stenosis by SRU consensus criteria.
Question 2: In vertebral artery assessment, which waveform pattern indicates subclavian steal syndrome?
- Monophasic antegrade flow
- Biphasic flow with systolic deceleration
- Complete reversal of diastolic flow only
- Alternating or fully reversed flow direction (Correct answer)
Correct answer: Alternating or fully reversed flow direction
Subclavian steal syndrome produces alternating (partial steal) or fully reversed (complete steal) vertebral artery flow due to proximal subclavian artery stenosis/occlusion.
Question 3: Which vessel is the most common site for fibromuscular dysplasia (FMD) in the extracranial carotid system?
- Common carotid artery
- Internal carotid artery at its origin
- Mid-to-distal internal carotid artery (Correct answer)
- External carotid artery
Correct answer: Mid-to-distal internal carotid artery
FMD most commonly affects the mid-to-distal ICA, producing a classic 'string of beads' appearance on imaging.
Question 4: A patient has no detectable ICA flow on duplex. What finding would suggest occlusion rather than a technically difficult exam?
- High-resistance CCA waveform with absent diastolic flow (Correct answer)
- Low-resistance CCA waveform with preserved diastole
- Normal ECA waveform with low diastolic flow
- Increased PSV in the contralateral ICA
Correct answer: High-resistance CCA waveform with absent diastolic flow
ICA occlusion causes the ipsilateral CCA to develop a high-resistance, low-diastolic waveform because the high-resistance ECA becomes the dominant outflow.
Question 5: What is the normal peak systolic velocity range for the common carotid artery in adults?
- 20-40 cm/s
- 60-100 cm/s (Correct answer)
- 100-150 cm/s
- 150-200 cm/s
Correct answer: 60-100 cm/s
Normal CCA PSV is typically 60-100 cm/s; values above this threshold (especially >125 cm/s) may indicate proximal or tandem disease.
Question 6: When scanning the vertebral artery, which insonation window is typically used to visualize the V2 segment?
- Suboccipital window
- Transtemporal window
- Between the transverse processes of C2-C6 (Correct answer)
- Anterior to the sternocleidomastoid muscle
Correct answer: Between the transverse processes of C2-C6
The V2 (foraminal) segment of the vertebral artery is imaged as it passes through the transverse foramina of C2-C6, visualized between the acoustic shadows of the transverse processes.
Question 7: Which finding on carotid duplex most reliably differentiates a near-occlusion from a complete ICA occlusion?
- Presence of an intraluminal thrombus
- Detection of a trickle of color flow with power Doppler (Correct answer)
- High-resistance CCA waveform
- Absence of diastolic flow in the ECA
Correct answer: Detection of a trickle of color flow with power Doppler
Power Doppler or sensitive color Doppler detecting a trickle of residual flow confirms near-occlusion rather than complete occlusion, which is clinically critical for surgical planning.
VT Carotid & Vertebral Ultrasound 2
What PSV ratio (ICA/CCA) is used to classify a 70-99% ICA stenosis per the SRU consensus criteria?