High-resolution magnetic resonance imaging of normal and atherosclerotic human coronary arteries ex vivo: Discrimination of plaque tissue components

Background: Noninvasive detection of plaque lipid and calcium in human athe rosclerosis may have clinical utility, because the presence of each may be associated with increased risk of plaque disruption. Magnetic resonance ima ging (MRI) has the potential to detect both plaque lipid and calcium. Howev er, no previous studies have: 1) used an MR coil with sufficient resolution to image the components of human coronary arteries, 2) evaluated the utili ty of a combination of different MR contrast weightings in discriminating p laque components in human coronary arteries, or 3) used sensitive and speci fic histological stains for lipid and calcium to determine their MR image c haracteristics in human atherosclerosis. Methods: Using a custom-made surface coil on a whole-body, 1.5T MRI scanner , high resolution MR images were obtained from 22 nonatherosclerotic and at herosclerotic human coronary artery segments and then compared with histolo gical sections stained for neutral lipid, calcium, and fibrous and cellular components. Results: With a multicontrast protocol using T1-, proton density-, and T2-w eighted images, statistically significant differences were found among MR i mage contrast values for regions identified by histological stains as conta ining lipid only, calcium only, mixed lipid and calcium, or fibrous tissue. All four of these histologically defined region types could be differentia ted from one another by a multicontrast MRI protocol. Of the 22 segments, 1 0 (45%) contained areas with combined plaque lipid and calcium; calcium wou ld not have been recognized histologically in these regions without the use of a specific calcium stain. Conclusions: These results demonstrate that multicontrast MRI can produce r emarkably high-resolution images and can discriminate between clinically re levant components (of the atherosclerotic vessel wall.