OBJECTIVES: Computed tomography is used routinely for coronary angiography and higher-risk features of plaques can also be identified. However, the ability of CT to discriminate individual plaque components and classify plaques according to accepted histological definitions is unknown.
METHODS: We first determined CT attenuation ranges for individual plaque components using combined in vivo CT co-registered with virtual histology intravascular ultrasound (VH-IVUS) in 108 plaques from 57 patients.
RESULTS: Comparison with contrast attenuation created plaque/contrast attenuation ratios that were significantly different for each component. In a separate validation cohort of 47 patients, these “Plaque Maps” correlated significantly with VH-IVUS-determined plaque component volumes (necrotic core (r=0.41, p=0.002), fibrous plaque (r=0.54, p<0.001), calcified plaque (r=0.59, p<0.001), total plaque (r=0.62, p<0.001)). We also assessed VH-IVUS and CT Plaque Maps against co-registered histology in 72 (VH-IVUS) and 87 (CT) segments from 8 post-mortem coronary arteries. The diagnostic accuracy of CT to detect calcified plaque (83% vs. 92%), necrotic core (80% vs. 65%) and fibroatheroma (80% vs. 79%) was comparable to VH-IVUS. However, while VH-IVUS could identify thin-cap fibroatheromas (TCFA) with a diagnostic accuracy of between 74-82% (depending on the TCFA definition used), the spatial resolution of CT prevented direct identification of TCFA.
CONCLUSIONS: CT-derived Plaque Maps based on contrast-adjusted attenuation ranges can define individual plaque components with a similar accuracy to VH-IVUS ex vivo. However, coronary CT Plaque Maps could not reliably classify plaques and identify TCFA, such that high-risk plaques may be misclassified or overlooked. Beau Allen Womens Jersey