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.