Retrospective correlation of MRI and angiographic findings in nine patients with suspected cervical vascular dissections revealed MRI evidence of vessel abnormalities in eight patients, seven of whom proved to have arterial dissections. One patient whose MRI showed no abnormalities also proved to have a dissection, shown by angiography. Two patients had associated pseudoaneurysms not demonstrated by MRI. Five dissections involved the carotid arteries and three the vertebral arteries. Seven of the nine patients had associated transient neurologic deficits, while two had permanent deficits. Frank infarction of the brain was demonstrated by MRI in five cases. MRI findings suggestive of dissection included: (1) increased signal from the entire vessel; (2) a border of increased signal surrounding the lumen, with luminal narrowing; (3) poor or absent visualization of the vessel; and (4) significant compromise of the vessel lumen by adjacent abnormal increased signal tissue.