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-mm cross-section and CDD was defined as the maximum percent difference in contrast densities in the lesion with respect to the proximal normal reference.
Results: CDD was strongly correlated with plaque burden; NCP (r=0.89), CP (r=0.76), and total plaque (r=0.91), plaque length (r=0.91) and maximal stenosis severity (r=0.93, all P-values <0.0001). Among 195 vessels, 43 vessels had impaired regional MFR≤2. Vessels with impaired regional MFR had higher total plaque burden (median 38% vs. 0, P=0.0001), higher frequency of maximal stenosis≥50% (33% vs.13%, P=0.003), and higher CDD (median 9% vs. 0, P=0.0003). For prediction of impaired MFR, area under the receiving operator characteristics curve for combined CDD≥18% and maximal stenosis>50% was 0.66 (95% CI:0.57-0.74), greater than for maximal stenosis>50% (0.60, 95% CI:0.52-0.67; P=0.04). In multivariable analysis, CDD≥18% was the only metric significantly associated with impaired MFR, adjusting for age, gender, total plaque burden and maximal stenosis>50% (odds ratio:2.7, 95% CI:1.1-6.5; P=0.03).
Conclusions: Contrast density difference can significantly improve identification of regional vascular dysfunction, over stenosis severity.
Author Disclosures: Y. Otaki: None. M. Hell: None. A. Schuhbaeck: None. L.E. Juarez-Orozco: None. H. Gransar: None. S. Achenbach: None. G. Germano: None. D. Berman: None. A. Meave: None. P. Slomka: None. E. Alexanderson: None. D. Dey: None.
- © 2016 by American Heart Association, Inc.