MR imaging of the internal carotid artery in ischemic cerebrovascular disorders--clinical and angiographic correlation.

This study was intended to correlate the appearance of the cavernous segment of the carotid artery on MR images with the presence of significant stenosis or occlusion of the cervical carotid artery as seen on angiograms in 37 patients with cerebrovascular disorders who had brain MRI and arteriography. Three patients demonstrated an isointense signal within the carotid artery's cavernous segment, correlating with complete carotid occlusion as seen angiographically. Ten patients had variable signal intensity and/or luminal narrowing in the carotid siphon; seven of these findings correlated with angiographic evidence of carotid occlusion, while carotid branch occlusion was seen angiographically in the other three. The demonstration of normal signal void within a normal-appearing cavernous segment of the internal carotid artery in the remaining 24 patients correlated with an absence of significant stenosis within the cervical segment in 21 patients. In the remaining three, significant disease of the internal carotid artery was found. Isointensity or luminal irregularity within the intracranial carotid artery can indicate complete occlusion or slow flow. The presence of normal flow void in the intracranial segment does not exclude significant abnormality of the cervical segment of the carotid artery.