Near-occlusion is difficult to diagnose with common carotid ultrasound methods

Figures

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  Fig. 1. Two cases of left-sided near-occlusion. a Near-occlusion with full collapse, sagittal CTA. Beyond a severe stenosis (white arrowhead), the distal ICA is significantly size-reduced with a threadlike appearance. Distal ICA is 0.8 mm in diameter. b Near-occlusion without full collapse, coronal CTA. Beyond severe stenosis (white arrowhead), the distal ICA is normal-appearing but relatively small (white arrow, 2.8 mm diameter), smaller than contralateral distal ICA (black arrowhead, 3.9 mm diameter) and similar to ECA (black arrow, 2.4 mm diameter)

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  Fig. 2. Ultrasound findings in two cases with near-occlusion. a Severe stenosis with low stenosis velocity, distinguishable from conventional stenosis by the low velocity. b Severe stenosis with high stenosis velocity, difficult to distinguish from conventional stenosis

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  Fig. 3. Study flow chart. *Excluding 37 exams with insufficient quality and one that could not be retrieved. †Only cases without CTA (from any referral source) where DUS referral was from the stroke unit or case sent to stroke unit after identification of stenosis or occlusion on DUS

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  Fig. 4. Comparison of CT-angiography (bars) and ultrasound findings (colors). Near-occlusion on ultrasound denotes any indication of near-occlusion, where two cases with <50% stenosis had intermediate PSV and diagnosed as <50% stenosis in the report