Abstract 65: Magnetic Resonance Plaque Imaging Before Carotid Artery Stenting (MR-CAS) Study: Initial Results

Abstract

Background: Carotid artery stenting (CAS) has recently emerged as a potential alternative to carotid endarterectomy. A major disadvantage of CAS is the high incidence of periprocrdural cerebral embolization. Previous studies suggested carotid plaque composition as lesion-specific risk factors for cerebral embolization during CAS, yet prospective studies are lacking. Magnetic resonance imaging (MRI) is a validated, noninvasive technique that affords quantitative analysis of carotid plaque tissue composition. MR-CAS is a prospective multicenter observational study to test the hypothesis that carotid plaque characteristics evaluated by pre-surgical MRI predict ischemic complications after CAS. Materials and Methods: We enrolled 128 arteries which underwent CAS. Multicontrast MRI was performed prior to CAS. Quantitative analysis of carotid plaque composition was done blinded to clinical information, including measures of intraplaque hemorrhage (IPH), lipid-rich necrotic core (LRNC), and calcification. Pre- and post-CAS diffusion weighted (DW) MRI were performed to detect new cerebral infarction after CAS. New ischemic symptoms within 30 days after CAS were also recorded. Associations between quantitative measures of plaque composition and new ischemic lesions on DW-MRI and new ischemic symptoms were evaluated. Results: Fifty arteries (39%) had new DW-MRI positive lesions in the ipsilateral carotid territory after CAS. Five patients (3.9%) developed new ischemic symptoms within 30 days after CAS. There were no significant differences in IPH volume or LRNC volume between the groups with and without ipsilateral DW-MRI positive lesions (IPH: 42 mm 3 [95%CI: 0-1140] vs. 20 mm 3 [0-804] p=0.55, LRNC: 240 mm 3 [0-1606] vs. 312 mm 3 [0-1374] p=0.76). However, IPH and LRNC volume were significantly larger in the patients with new ischemic symptoms after CAS than those without (IPH: 323 mm 3 [95%CI: 18-478] vs. 22 mm 3 [0-1140] p=0.009, LRNC: 501 mm 3 [392-1185] vs. 261 mm 3 [0-1606] p=0.013). Conclusions: Quantitative measures of carotid plaque composition predicted new ischemic symptoms after CAS but not new DW-MRI.