Carotid plaque signal differences among four kinds of T1-weighted magnetic resonance imaging techniques: A histopathological correlation study

Several magnetic resonance (MR) imaging techniques are used to examine atherosclerotic plaque of carotid arteries; however, the best technique for visualizing intraplaque characteristics has yet to be determined. Here, we directly compared four kinds of T1-weighted (T1W) imaging techniques with pathological findings in patients with carotid stenosis. A total of 31 patients who were candidates for carotid endarterectomy were prospectively examined using a 1.5-T MRI scanner, which produced four kinds of T1W images, including non-gated spin echo (SE), cardiac-gated black-blood (BB) fast-SE (FSE), magnetization-prepared rapid acquisition with gradient echo (MPRAGE), and source image of three-dimensional time-of-flight MR angiography (SI-MRA). The signal intensity of the carotid plaque was manually measured, and the contrast ratio (CR) against the adjacent muscle was calculated. CRs from the four imaging techniques were compared to each other and correlated with histopathological specimens. CRs of the carotid plaques mainly containing fibrous tissue, lipid/necrosis, and hemorrhage were significantly different with little overlaps (range: 0.92-1.15, 1.22-1.52, and 1.55-2.30, respectively) on non-gated SE. However, BB-FSE showed remarkable overlaps among the three groups (0.89-1.10, 1.07-1.23, and 1.01-1.42, respectively). MPRAGE could discriminate fibrous plaques from hemorrhagic plaques but not from lipid/necrosis-rich plaques: (0.77-1.07, 1.45-2.43, and 0.85-1.42, respectively). SI-MRA showed the same tendencies (1.01-1.39, 1.45-2.57, and 1.12-1.39, respectively). Among T1W MR imaging techniques, non-gated SE images can more accurately characterize intraplaque components in patients who underwent CEA when compared with cardiac-gated BB-FSE, MPRAGE, and SI-MRA images. (orig.)