Characterisation of carotid atherosclerotic plaque: comparison between magnetic resonance imaging and histology

Purpose. The aim of this study was to identify and characterise by magnetic resonance imaging (MRI) carotid plaque constituents such as lipid-rich necrotic core, intraplaque haemorrhage and calcification in patients treated with carotid endarterectomy (CEA) using histological evaluation as the reference standard. Materials and methods. Nineteen patients (13 men and six women) scheduled for CEA between March and August 2004 were imaged on a 1.5-T scanner (Magnetom Symphony, Siemens, Erlangen, Germany). The protocol included four types of sequences [T1. T2, proton density (PD) and three-dimensional time of flight (3D-TOF)]. Images were reviewed for integrity of the fibrous cap, presence of lipid-rich necrotic core, intraplaque haemorrhage and calcification. Signal intensity was assessed relative to the adjacent sternocleidomastoid muscle. Four cross-sections for each lesion were compared with the corresponding histological specimens and independently reviewed by two radiologists and one pathologist. Results. MRI detected lipid-rich necrotic core with a sensitivity and specificity of 91.6% and 95.0%, respectively, whereas it defined intraplaque haemorrhage alone with a sensitivity and specificity of 91.6% and 100%. respectively. Calcification was recognised with a sensitivity and specificity of 80% and 93.7%, respectively. Conclusions. MRI is able to identify signs of carotid plaque instability with a high sensitivity and specificity. Therefore, it may be useful in evaluating and guiding the treatment of haemodynamically nonsignificant stenoses with a potential embolic risk and, in the future, to assess coronary plaque.