Abstract 15836: Assessment of High-risk Atherosclerotic Plaque by Dual-energy Coronary Computed Tomography in Sudden Cardiac Death Patients: Mapping With Histopathologic Gold Standard

Introduction: Necrotic core (NC) is a surrogate of high-risk plaque identified by histopathologic analysis in sudden coronary death (SCD) victims. Non-invasive discrimination of NC from fibrous plaque (FP) is challenging at present due to overlapping Hounsfield Units (HU) between NC and FP. Dual-energy CT (DECT) as a novel imaging technique, enables differentiation of tissue materials based upon atomic density and evaluation of images based on monochromatic energies (MCE) rather than polychromatic spectra of energies by single-energy CT (SECT). Hypothesis: To determine whether DECT could improve discrimination of high-risk plaque features, and compare DECT-MCE to SECT for discrimination of NC from FP. Methods: Coronary specimens were obtained from 12 post-mortem hearts from autopsy-validated SCD victims. NC and FP were identified on histologic sections. Histology images with a ≥90% uniform region of interest (ROIs) of NC and FP, and corresponding to a 0.4 mm 2 area, were created. HU values for SECT and DECT-MCE (ranging from 40 to 140 kilo-electron voltages [keV]) were calculated for histologic ROIs based on NC and FP. Standardized HU were defined as the mean HU measure divided by the corresponding lumen mean HU measure for NC and FP. The maximum difference in standardized median HU values between NC and FP were then calculated at each DECT-MCE to determine the optimal viewing mode for diagnosis of NC. Results: Of 136 sections, a total 56 ROIs (23 NCs and 33 FPs) were measured. Across a range of DECT-MCE, varying minimum differences in standardized median HU values between NC and FP was displayed, with the highest difference at 140 keV (0.25, NC 0.12, FP 0.37) and lowest difference at 60 keV (0.10, NC: 0.37; FP: 0.47). Compared to DECT-MCE, SECT was poorer at discrimination of NC and FP, with a minimum difference of 0.07 between NC and FP. Conclusions: DECT is superior to SECT for discrimination of NC and FP in coronary lesions from SCD victims, with a 140 keV MCE performing best for DECT.