Background: To investigate the diagnostic performance of quantified plaque analysis and high-risk plaque characterization by coronary computed tomography angiography (CCTA) for identifying thin-cap fibroatheroma (TCFA).Methods: Patients who underwent both CCTA and intravascular ultrasound (IVUS) within 4 weeks were retrospectively included. CT-derived quantitative and qualitative parameters, including diameter stenosis, minimal lumen area (MLA), low attenuation plaque (LAP) volume napkin-ring sign (NRS), positive remodeling (PR) and spotty calcification, were recorded. TCFA lesions and non-TCFA lesions were determined by IVUS.Multivariate regression analysis was used to determine the independent predictors of TCFA lesions.Results: Sixty-five patients (mean age: 69.8±9.2 years, 29 females) with 89 lesions were finally included.LAP and NRS were more frequently presented in the group of TCFA lesions. The mean LAP volume of TCFA lesions was significantly larger than that of non-TCFA lesions [16.5 (11.0-23.0) vs. 0 (0-1.5) mm 3 , P<0.001]. According to multivariate logistic regression analysis, LAP volume was the only significant predictor for IVUS-confirmed vulnerable plaques (odds ratio =3.294, 95% confidence interval: 1.177-9.223, P=0.023). LAP volume showed largest area under curve (AUC) for diagnosing TCFA lesions (AUC =0.901, 95% confidence interval: 0.819-0.954, P<0.0001). When using >8 mm 3 as the best cutoff value, the diagnostic accuracy, sensitivity and specificity of LAP volume for predicting TCFA lesions were 91.0% (81/89), 84.6% (22/26) and 96.8% (61/63) respectively.Conclusions: CT-derived LAP volume of TCFA lesions was significantly higher than those of non-TCFA lesions. LAP volume was the strongest predictor for TCFA lesions as validated by IVUS.

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