The feasibility and limitation of coronary computed tomographic angiography imaging to identify coronary lipid-rich atheroma in vivo: Findings from near-infrared spectroscopy analysis

Background: Coronary computed tomography angiography (CCTA) non-invasively visualizes lipid-rich plaque. However, this ability is not fully validated in vivo. The current study aimed to elucidate the association of CCTA features with near-infrared spectroscopy-derived lipidic plaque measure in patients with coronary artery disease. Methods: 95 coronary lesions (culprit/non-culprit = 51/44) in 35 CAD subjects were evaluated by CCTA and NIRS imaging. CT density, positive remodeling, spotty calcification, napkin-ring sign and NIRS-derived maximum 4-mm lipid-core burden index (maxLCBI_4mm) were analyzed by two independent physicians. The association of CCTA-derived plaque features with maxLCBI_4mm ≥ 400 was evaluated. Results: The median CT density and maxLCBI_4mm were 57.7 Hounsfield units (HU) and 304, respectively. CT density (r = -0.75, p < 0.001) and remodeling index (RI) (r = 0.58, p < 0.001) were significantly associated with maxLCBI_4mm, respectively. Although napkin-ring sign (p < 0.001) showed higher prevalence of maxLCBI_4mm ≥ 400 than those without it, spotty calcification did not (p = 0.13). On multivariable analysis, CT density [odds ratio (OR) = 0.95, 95% confidence interval (CI) = 0.93–0.97; p < 0.001] and positive remodeling [OR = 7.71, 95%CI = 1.37–43.41, p = 0.02] independently predicted maxLCBI_4mm ≥ 400. Receiver operating characteristic curve analysis demonstrated CT density <32.9 HU (AUC = 0.92, sensitivity = 85.7%, specificity = 91.7%) and RI ≥ 1.08 (AUC = 0.83, sensitivity = 74.3%, specificity = 85.0%) as optimal cut-off values of maxLCBI_4mm ≥ 400. Of note, only 52.6% at lesions with one of these plaque features exhibited maxLCBI_4mm ≥ 400, whereas the frequency of maxLCBI_4mm ≥ 400 was highest at those with both features (88.5%, p < 0.001 for trend). Conclusions: CT density <32.9 HU and RI ≥ 1.08 were associated with lipid-rich plaque on NIRS imaging. Our findings underscore the synergistic value of CT density and positive remodeling to detect lipid-rich plaque by CCTA.