Fig. 1.

Carotid near-occlusions, coronal views. a Right-sided near-occlusion without full collapse. Beyond a severe stenosis (white arrowhead), the distal ICA is normal-appearing (white arrow, diameter 2.8 mm). However, the distal ICA is smaller than contralateral ICA (black arrowhead, ICA ratio 0.72) and similar to ipsilateral ECA (black arrow, ECA ratio 0.97). It was classified as without full collapse with all presented definitions. b Right-sided near-occlusion with full collapse. Beyond a severe and calcified stenosis (white arrowheads), the distal ICA has a threadlike appearance (white arrow, diameter 1.2 mm), clearly smaller than both contralateral ICA (black arrowhead, ICA ratio 0.20) and ipsilateral ECA (black arrow, ECA ratio 0.40). It was classified as with full collapse with all presented definitions