[MRI of internal carotid occlusion and high-grade carotid stenosis]

Magnetic resonance imaging (MRI) of twelve patients with angiographically proved internal carotid artery (ICA) occlusions and a patient with high-grade ICA stenosis was retrospectively reviewed. In one of the occluded ICA cases, the bilateral ICAs were involved. All patients were examined by a 1.5 Tesla system, using spin-echo pulse sequences. Both absence of normal flow void and decreased caliber of the cavernous portion of the ICA were detected in all patients. In ten of the thirteen occluded ICAs, flow void was completely absent. Most of the occluded arteries were isointense relative to gray matter on T1-weighted images, and were mildly hypointense on T2-weighted images. "Partial flow void" was observed in four cases, including the high-grade stenosis patient. So-called "border zone infarcts" were detected in seven patients (eight hemispheres). In three of the thirteen cases, however, cerebral infarcts relating to the ICA occlusions or high-grade stenosis were not observed. Since detection of abnormal ICA before cerebral infarct has occurred is extremely significant, we want to stress that abnormal ICA must be routinely searched for in the routine review of MRI of the head.