Abstract 4372297: Classification of Adjacent Coronary Arterial Plaques Using Late Phase Effective Atomic Numbers and Electron Densities of Focal Pericoronary Adipose Tissue on Contrast Enhanced Spectral Computed Tomography

Introduction: Inflammation in pericoronary adipose tissues (PCATs) may occur focally at adjacent plaque sites in the coronary arterial system as suggested by abnormal late-phase enhancement on contrast computed tomography (CT). Hypothesis: Using late-phase effective atomic numbers (EANs) and electron densities (EDs) determined by enhanced spectral CT as new parameters, focal characteristics of PCATs may be used to classify adjacent coronary arterial plaques. Methods: This is a retrospective analysis of 13 patients (eight males, 60±11 years), scheduled for pulmonary vein isolation, who underwent cardiac spectral CT (7500, Philips) and routine late-phase CT contrast acquisition to evaluate left atrial thrombi. From non-contrast and early- and late-contrast data, EANs and EDs (% relative to water) of PCATs were determined at five sites per patient, as well as coronary arterial plaques, on enhanced CT images. Results: From a total of 71 sites in 13 patients using early-phase CT, 30 sites had no plaques (group 1), three sites had only calcified plaques (group 2), 26 sites had only non-calcified plaques (group 3), and 12 sites had mixed plaques (group 4). Mean EANs and EDs of PCATs at corresponding sites were 6.7, 6.7, 6.4, and 6.6 (EANs), and 94.8, 95.6, 93.7 and 94.1 (EDs) in groups 1–4, respectively, in non-contrast phase; 6.1, 6.9, 6.1, and 6.2 (EANs) (Group 2>Groups 3 and 4, both P < 0.05), and 93.4, 95.4, 93.6, and 93.5 (EDs) in groups 1–4, respectively, in early phase; 6.9, 7.3, 6.5, and 6.4 (EANs) (Group 4<Groups 1 and 2, both P < 0.05), and 93.4, 97.5, 93.8, and 93.7 (EDs) (Group 2>Groups 1, 3, and 4, all P < 0.05) in groups 1–4, respectively, in late phase. Conclusion: This is the first study to evaluate focal PCATs by EANs and EDs and their site-by-site relationship to coronary arterial plaques. Such new CT parameters, especially in late phase on contrast-enhanced CT, may predict the future occurrence of adjacent coronary arterial plaques related to PCAT inflammation.