[MR imaging of internal carotid artery occlusion]

Five patients with internal carotid artery occlusion were studied with MR imaging at 0.22 T. At the carotid siphon, occluded vessels showed absence of flow void in three patients. But two cases had "partial flow void" which mimicked small arterial caliber. In these patients angiography showed collateral circulation to the carotid siphon. So the partial flow void in the carotid siphon suggested internal carotid artery occlusion with collateral circulation.