Relationship between carotid artery remodeling and plaque vulnerability with T1-weighted magnetic resonance imaging

Background The aim of this study was to validate the relationship between carotid artery remodeling defined as the carotid remodeling index (CRI) and plaque vulnerability by comparing the degree of outward remodeling calculated using 3-dimensional inversion recovery-based T1-weighted imaging (magnetization-prepared rapid acquisition gradient echo [MPRAGE]) with the symptomatology and histology of plaques extracted during carotid endarterectomy. Methods Sixty-one patients with 50% stenosis or more (North American Symptomatic Carotid Endarterectomy Trial criteria) were included. The average rate of stenosis was 79.8%. The CRI was determined by measuring the external cross-sectional vessel area (CSVA) at the maximum stenosis of the internal carotid artery (ICA) and dividing it by the external CSVA at the distal ICA (unaffected by atherosclerosis) using MPRAGE imaging. Results The CRI was significantly higher in symptomatic patients compared with asymptomatic patients (1.98 ±.26 versus 1.68 ±.24, P <.0001). A higher CRI positively correlated with the necrotic core area (r =.57, P <.0001) and negatively correlated with the fibrous cap thickness (r = -.33, P =.01). It was also significantly associated with severe intraplaque hemorrhage (P <.0001) and the prevalence of cap inflammation with macrophage (P =.03) and lymphocyte (P =.01) infiltration. Conclusions The larger outward remodeling of the carotid artery on MPRAGE imaging had symptomatic carotid plaques and histologically vulnerable plaques. This study indicates that MPRAGE imaging is useful for the assessment of carotid artery remodeling.