Unstable plaques hide in heavily calcified coronary arteries

摘要

Background: The napkin-ring sign (NRS) was accepted as unstable plaques at coronary computed tomography angiography (CCTA). However, the incidence is relatively low. We sought to assess whether the newly defined diamond-attenuation-sign DAS, defined as a qualitative plaque feature in a mixed plaque (MP) on CCTA cross-section images by the presence of two features: a visual calcification (in the shape of a diamond) accompanied by an annular-shape lower attenuation plaque tissue surrounding the lumen like a ring, could be accurately identified as unstable atherosclerotic plaques. Methods: Eight heart transplant recipients (8 male; mean age, 48.5 +/- 11.6 years; range, 37-65 years) underwent CCTA exams prior to heart transplant surgery. Segment-based CCTA sections were independently evaluated for various plaque patterns including non-calcified plaque (NCP) with NRS (NCP-NRS), NCP without NRS (NCP-non-NRS), MP with DAS (MP-DAS), MP without DAS sign (M :P-non-DAS), and calcified plaque (CP). Results: NCP-NRS plaques in 6.4 (23/358), NCP-non-NRS plaques in 24.0 (86/358), MP-DAS plaques in 18.2 (65/358), MP-non-DAS plaques in 20.1 (72/358), and calcified-plaques in 7.0 (25/358) of all cases. The specificity and positive predictive values of the MP-DAS and NCP-NRS signs to identify unstable plaque features were excellent (97.1 vs. 98.6, 90.8 vs. 87.0, respectively). DAS plaques were more frequently seen on CCTA exams than that of NRS (39.3 vs. 13.3, respectively, P=0.001). The diagnostic performance of MP-DAS to identify unstable coronary lesions was superior compared to NCP-NRS area under the receiver operating characteristic curve (ROC), 0.756; 95 CI: 0.717-0.791 vs. 0.558; 95 CI: 0.514-0.600, respectively, P<0.001. Conclusions: Both the DAS and NRS had a high specificity and positive predictive value for the presence of unstable lesions. DAS was a better identification of unstable atherosclerotic plaques in the assessment of plaque-calcification-pattern (PCP).