Abstract 17206: Identification of Coronary Vascular Dysfunction by Contrast Density Difference Measured From Coronary CT Angiography

Introduction: Contrast density difference (CDD), which can be measured by semi-automated software in coronary CT angiography (CTA), has been shown to predict lesion-specific ischemia. We investigated if quantitative CDD predicts coronary vascular dysfunction by 13N-Ammonia PET. Methods: Sixty-five consecutive patients (41 men, 62±10 years) underwent combined rest-stress 13N-ammonia PET and CTA by hybrid PET/CT. Regional myocardial flow reserve (MFR) was measured from PET by automated analysis using a simplified 2-compartment model for 13N-ammonia. Impaired MFR was defined as regional MFR ≤2. In CTA, 195 vessels were analyzed by semi-automated software to quantify plaque characteristics over the entire coronary tree, including non-calcified (NCP), calcified (CP), and total plaque volumes, corresponding plaque burden (plaque volume x 100%/vessel volume), plaque length, stenosis, and CDD. To determine CDD, luminal contrast density, defined as attenuation per unit area, was measured automatically for each 1-m...