The carotid ring sign is a radiological sign described in CT angiography of acute true proximal internal carotid artery occlusion.
The carotid ring sign is seen on axial single-phase CT angiographic maximum intensity projection images and refers to either a ring-like region of contrast enhancement of the internal carotid artery wall, involving >50% of the wall circumference at the level of maximal stenosis, and/or an intraluminal hypodensity 1,2.
Clinical importance
It is a useful sign in differentiating true carotid occlusion in the acute setting, predominantly due to progressive atherosclerotic stenosis with or without a tandem lesion, from carotid pseudo-occlusion, often due to a more proximal intracranial embolus 1. In one study, the presence of the carotid ring sign had a specificity of 94% and a sensitivity of 70% for diagnosing a true carotid occlusion in the acute setting 1.
Additionally, the carotid ring sign is useful in differentiating acute from chronic true carotid occlusion 2. In another study, the presence of the carotid ring sign had a 69% specificity and 89% sensitivity for diagnosing an acute true carotid occlusion 2.
Differential diagnosis
calcific plaque of the carotid wall 2,3
Unable to process the form. Check for errors and try again.