In vivo T2-mapping and segmentation of carotid artery plaque components using magnetic resonance imaging at 1.5T

Atherosclerosis is regarded as a lifestyle disease, where artery lumen is reduced due to deposition of calcium and fatty materials such as cholesterol and triglyceride. These plaques can become unstable and rupture, resulting in life threatening cardiovascular events. Multicontrast cardiovascular magnetic resonance (CMR) has been used on 1.5T and 3T scanners to identify carotid plaques and study their morphology in vivo, however it does not provide quantitative information. Carotid arteries of healthy volunteers and patients with known atherosclerosis were imaged on a 1.5T Siemens Aera MRI scanner. Standard imaging protocol consisted of a TOF sequence to localize the carotid bifurcation, followed by the acquisition of T1-, T2- and PD-weighted images to assess the plaque qualitatively. Finally, T2 relaxation time mapping was performed through the plaque center using a Multiple-Spin-Echo sequence. Custom software was written in MATLAB to generate T2 maps and discriminate different plaque types, confirmed by multicontrast CMR. This study showed that T2 mapping of atherosclerotic plaque is possible on a 1.5T scanner. Measurements demonstrated the ability to discriminate plaque components on T2 maps, which are in good agreement with conventional multicontrast CMR.