Magnetic resonance findings in spontaneous dissection of the cervical internal carotid artery--case report.

The magnetic resonance (MR) appearance of a spontaneous dissection of the cervical internal carotid artery (ICA) in a 53-year-old male is described. Cerebral angiograms demonstrated a long-segment stenosis of the left cervical ICA beginning above the common carotid bifurcation and extending to the skull base ("string sign"). T1-, T2-, and proton density-weighted MR images of the upper neck revealed a high-intensity crescent mass expanding the arterial wall and narrowing the arterial lumen of the left ICA. This high-intensity mass was considered to represent the mural hematoma of the involved ICA. Gradual improvement of the dissection was confirmed by both angiography and MR imaging. Cerebral angiograms have shown pathognomonic findings such as double lumen and intimal flap in only some patients with ICA dissection. Our experience suggests that MR demonstration of the mural hematoma is specific and important for diagnosis and follow-up in cases of spontaneous dissection of the cervical ICA.