Fig. 5.

Illustration of the “rim”-sign on contrast-enhanced CT. The axial CT-image at the level of the internal carotid artery reveals only minimal small calcifications in the right ICA (arrowhead in a), and a plaque with calcified and non-calcified components in the left ICA (arrow in b). Close examination of this plaque reveals a small semicircular rim of adventitial calcifications at the periphery of the plaque (<2 mm thickness) with a larger (>2 mm) non-calcified plaque component bordering the lumen. This plaque phenotype is known as a positive “rim”-sign, a feature associated with the presence of intraplaque hemorrhage and as such with higher stroke risk. Reporting of this type of plaque is significant, as the luminal narrowing is only moderate and by itself according to NASCET criteria considered non-significant