Small In-Stent Low Density on CT Angiography after Carotid Artery Stenting

SUMMARY: Carotid stenting (CAS) for carotid stenosis has developed rapidly over the last decade. Instent low density area supposed plaque protrusion or thrombus is sometimes observed on CT angiography after CAS. We evaluate the frequency and time course of the small in-stent low density after carotid artery stenting and discuss its nature and clinical significance. Between May 2005 to November 2007, 23 CASs were performed for 20 patients with carotid artery stenosis. All patients had no instent defect on digital subtraction angiography (DSA) immediately after the procedure. Followup CT angiography was performed at seven 7-10 days, 1-2 months, 6 months, and then every 6 months following CAS. We retrospectively reviewed the follow-up CT angiographic findings and clinical ischemic events. Small in-stent low density areas on CT angiography were observed in 6 lesions (26%). Four cases were added warfarin to antiplatlets and the other two cases had antiplatlets only. The in-stent low density areas were disappeared within four months after CAS and no ischemic event was observed in five patients. In the other patient, a small in-stent low density area had decreased at one month after CAS, but another small in-stent low density area appeared at five months. Subacute small in-stent low density areas were frequently observed on CT angiography following CAS, however, the low density area will disappear without clinical events by medication in most case.