Evaluation of Carotid Plaque Composition by Computed Tomographic Angiography and Black Blood Magnetic Resonance Images

The purpose of this study was to evaluate quantitatively the composition of carotid plaque by computed tomographic (CT) angiography and qualitatively by black blood magnetic resonance images (MRI). Thirty-eight patients with high-grade carotid artery stenosis were included in this study. Ultrasonography, CT angiography and black blood MRI of the cervical carotid artery were performed, and the CT number was measured in Hounsfield units (HU). The average CT number of the 15 unstable plaques (39.5%) was 27.7+/-7.5 HU and that of the 23 stable plaques (60.5%) was 60.4+/-20.8 HU (p=0.0001). In the 23 patients with stable plaque, 21 demonstrated isointensity in T (1)- and T (2)-weighted images in the black blood MRI (p=0.0001). By using CT angiography and MRI, precise images of the pathology of the carotid arterial wall can be obtained. It is possible to evaluate the components of carotid artery plaque with high reliability by quantification of the CT number in CT angiography and performing black blood MRI as well as carotid ultrasonography.