Abstract T MP32: T1-Weighted Magnetic Resonance Imaging Evaluation of Carotid Artery Outward Remodeling in Carotid Endarterectomy and Stenting

Abstract

Objective: We evaluated carotid artery outward remodeling and plaque relative signal intensity (rSI) in patients undergoing carotid endarterectomy (CEA) or carotid artery stenting (CAS) by T1-weighted Magnetic Resonance Imaging (T1-MRI), in order to define their clinical significance in carotid revascularization. Methods: Eighty-eight lesions (51 CEA and 37 CAS; symptomatic at 54.9 and 45.7%, respectively) from 93 patients who underwent carotid revascularization at our institute were retrospectively considered. We evaluated the carotid artery remodeling parameter of luminal stenosis, which is determined by a ratio of external cross-sectional vessel area (CSVA) at maximum stenosis, and reference CSVA at the distal portion of the ICA (carotid remodeling index, CRI), and MR intensities of atherosclerotic plaque (rSI) using T1 MRI (magnetization-prepared rapid acquisition with gradient-echo [MPRAGE]), preoperatively. We divided carotid lesions into 4 groups using median CRI and rSI: L/L (CRI < 1.8, rSI < 2.5), L/H (CRI < 1.8, rSI ≥ 2.5), H/L (CRI ≥ , and rSI < 2.5), and H/H (CRI ≥ 1.8, rSI ≥ 2.5). The endpoint was defined as the detection of acute ipsilateral ischemia on diffusion-weighted imaging (DWI) within 72 h of treatment. Results: A significant correlation was found between CRI and rSI (r = 0.359, p = 0.0006). Mean CRI and rSI were significantly higher in lesions treated with CEA than with CAS. Small abnormalities were observed on DWI in 4 cases (7.8%) in CEA, and 10 (27.0%) in CAS (p = 0.01). In the CAS group, the observed frequency of DWI abnormalities in group L/L, L/H, H/L, H/H were 5.5%, 40.0%, 40.0%, and 55.5%, respectively (p = 0.03). In multivariate analysis, rate of stenosis (Odds Ratio [OR]: 1.19; 95% confidence interval [CI]: 1.04-1.48; p = 0.0082), and non-L/L lesions (OR: 29.65; 95% CI: 2.97-555.12; p = 0.002) were independent risk factors for cerebral embolism. In the CEA group, no significant relationship was observed between plaque parameters and DWI lesions. Conclusion: CRI and rSI are complementary parameters to predict a high-risk plaque for CAS, but not for CEA. Preoperative evaluation with T1 MRI is useful to make decisions about treatment strategy for carotid artery stenosis.