VT Lower & Upper Extremity Arterial 3 — Questions and Answers
Question 1: Which finding on a lower extremity arterial duplex most reliably differentiates a complete occlusion from a very high-grade stenosis?
- Absence of color Doppler signal alone
- No detectable spectral Doppler flow despite optimized gain settings and wall-filter reduction (Correct answer)
- Presence of acoustic shadowing posterior to the vessel
- A peak systolic velocity ratio exceeding 4.0
Correct answer: No detectable spectral Doppler flow despite optimized gain settings and wall-filter reduction
True occlusion is confirmed by absent spectral Doppler flow even after optimizing settings (low wall filter, low PRF, angle correction), since color flow alone can miss trickle flow.
Question 2: During Allen's test evaluation with duplex ultrasound, what finding confirms ulnar artery dominance to the palmar arch?
- Retrograde radial artery flow with radial compression only
- Maintenance of digital perfusion with radial artery compression and patent ulnar inflow (Correct answer)
- Absence of flow in the palmar arch at baseline
- Increased radial artery PSV during ulnar compression
Correct answer: Maintenance of digital perfusion with radial artery compression and patent ulnar inflow
Ulnar dominance is confirmed when palmar arch and digital perfusion are maintained during radial artery compression, indicating the ulnar artery supplies the arch.
Question 3: In evaluating suspected popliteal artery entrapment syndrome, which maneuver is most useful during duplex ultrasound?
- Passive ankle plantar flexion with knee extended
- Active plantar flexion against resistance or passive dorsiflexion (Correct answer)
- Hip abduction with external rotation
- Adson's maneuver (head rotation with deep inspiration)
Correct answer: Active plantar flexion against resistance or passive dorsiflexion
Active plantar flexion against resistance or passive dorsiflexion compresses the popliteal artery against the medial gastrocnemius head, reproducing flow abnormality in entrapment syndrome.
Question 4: Which Doppler angle is considered optimal for lower extremity arterial spectral Doppler acquisition?
- 0 degrees
- 45 degrees
- 60 degrees (Correct answer)
- 90 degrees
Correct answer: 60 degrees
A 60-degree Doppler angle is standard for lower extremity arterial studies, balancing signal quality with acceptable velocity calculation accuracy.
Question 5: A post-angioplasty duplex surveillance study shows a peak systolic velocity of 380 cm/s at the treated femoral artery segment with a ratio of 2.8. This result most likely indicates:
- Normal post-procedure hyperemia
- Moderate residual or recurrent stenosis (50–74%) (Correct answer)
- Occlusion at the treated segment
- Artifact from wall calcium at the stent edge
Correct answer: Moderate residual or recurrent stenosis (50–74%)
A PSV ratio of 2.0–4.0 at a stented or treated segment corresponds to 50–74% diameter stenosis requiring close follow-up.
Question 6: The anterior tibial artery originates from which vessel and passes through which anatomical structure to reach the anterior compartment?
- Popliteal artery; interosseous membrane (Correct answer)
- Femoral artery; adductor canal
- Posterior tibial artery; flexor retinaculum
- Peroneal artery; anterior intermuscular septum
Correct answer: Popliteal artery; interosseous membrane
The anterior tibial artery arises from the popliteal artery and passes anteriorly through the interosseous membrane to enter the anterior compartment.
Question 7: A patient presents with blue toe syndrome and a normal ABI. The most likely source of the emboli is:
- Aortic or iliac atherosclerotic plaque (Correct answer)
- Deep vein thrombosis with paradoxical embolism
- Arteriovenous malformation of the calf
- Varicose vein with superficial thrombophlebitis
Correct answer: Aortic or iliac atherosclerotic plaque
Blue toe syndrome with a normal ABI typically results from microemboli from proximal atherosclerotic plaque (aortoiliac or femoral), causing digital ischemia without flow-limiting stenosis.
VT Lower & Upper Extremity Arterial 3
Which finding on a lower extremity arterial duplex most reliably differentiates a complete occlusion from a very high-grade stenosis?