On carotid Doppler ultrasound, a patient shows peak systolic velocity (PSV) of 280 cm/s in the internal carotid artery (ICA) and 60 cm/s in the common carotid artery (CCA). The ICA/CCA PSV ratio is 4.67. Which degree of ICA stenosis does this correspond to?

• A 50–69% stenosis
• B 100% (occlusion)
• C Less than 50% stenosis
• D 70–99% stenosis (severe) ✓

Explanation

The Society of Radiologists in Ultrasound (SRU) consensus criteria define ≥70% ICA stenosis as ICA PSV ≥230 cm/s OR ICA/CCA PSV ratio ≥4.0 in the absence of occlusion. In this case PSV is 280 cm/s and ratio is 4.67, both exceeding the ≥70% threshold. 50–69% stenosis corresponds to ICA PSV 125–230 cm/s. Complete occlusion shows absent flow with no detectable PSV. Identification of ≥70% symptomatic carotid stenosis is a class I indication for carotid endarterectomy.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.