Significant extracranial carotid stenosis: detection on routine cerebral MR images.

Severe stenosis of the cervical internal carotid artery was detected on magnetic resonance images in three patients from a series of eight with abnormality of flow. In contrast to complete loss of "flow void" in the horizontal carotid within the petrous bone seen in patients with complete occlusion, these three patients had partial flow void in which there was a central area of signal void in the artery, surrounded by circumferential increase in signal in the outer third of the artery. This was seen on axial views at right angles to the long axis of the artery below the petrous bone and on "in-plane" sections through the horizontal carotid canal. An animal model with 70% and 90% carotid stenosis and carotid occlusion was created. The model with 70% stenosis showed no significant change. The 90% stenosis model showed partial flow void in the center of the lumen with peripheral signal exactly as seen in the human patients.