Helical CT for the follow-up of cervical internal carotid artery dissections.

PURPOSE The aim of this study was to assess the changes over time of internal carotid artery (ICA) dissections by using helical CT. METHODS Twenty-seven patients with 30 angiographically proved ICA dissections were followed up with helical CT at 7 to 62 months (median, 24 months) after conventional angiography. CT scans, analyzed independently by two radiologists in a blinded fashion, were evaluated for the presence of mural thickening, aneurysmal formation, and arterial occlusion. In cases without persisting occlusion or aneurysm, we measured the external diameter of the ICA at its upper segment. RESULTS The interobserver agreement was good. Mild mural thickening was observed in four cases of 30 previously dissected ICAs. All stenotic and nearly occlusive dissections without an aneurysm (n = 12) reverted to a normal or nearly normal diameter. Half the aneurysms resolved spontaneously (four of eight). Of the 10 occluded ICAs, nine were recanalized, but their external diameter was significantly smaller than that of normal carotid arteries, and a hypoplastic appearance was seen throughout the cervical segment of the ICA in three cases. CONCLUSION Most arterial lesions tend to improve or disappear spontaneously, but persisting ICA narrowing may be observed in the late course of occlusive-type dissections.