Dynamic Myocardial CT Perfusion Imaging for Evaluation of Myocardial Ischemia as Determined by MR Imaging

OBJECTIVES The aim of this study was to determine the feasibility of computed tomography (CT)-based dynamic myocardial perfusion imaging for the assessment of myocardial ischemia and infarction compared with cardiac magnetic resonance (CMR). BACKGROUND Sequential myocardial CT perfusion imaging has emerged as a novel imaging technique for the assessment of myocardial hypoperfusion. METHODS We prospectively enrolled subjects with known coronary artery disease who underwent adenosine-mediated stress dynamic dual-source CT (100 kV, 320 mAs/rot) and CMR (3-T). Estimated myocardial blood flow (eMBF) and estimated myocardial blood volume (eMBV) were derived from CT images, using a model-based parametric deconvolution technique. The values were independently related to perfusion defects (ischemic and/or infarcted myocardial segments) as visually assessed during rest/stress and late gadolinium enhancement CMR. Conventional measures of diagnostic accuracy and differences in eMBF/eMBV were determined. RESULTS Of 38 enrolled subjects, 31 (mean age 70.4 +/- 9.3 years; 77% men) completed both CT and CMR protocols. The prevalence of ischemic and infarcted myocardial segments detected by CMR was moderate (11.6%, n = 56 and 12.6%, n = 61, respectively, of 484 analyzed segments, with 8.4% being transmural). The diagnostic accuracy of CT for the detection of any perfusion defect was good (eMBF threshold, 88 ml/mg/min; sensitivity, 77.8% [95% confidence interval (CI): 69% to 85%]; negative predictive value, 91.3% [95% CI: 86% to 94%]) with moderate positive predictive value (50.6% [95% CI: 43% to 58%] and specificity (75.41% [95% CI: 70% to 79%]). Higher diagnostic accuracy was observed for transmural perfusion defects (sensitivity 87.8%; 95% CI: 74% to 96%) and infarcted segments (sensitivity 85.3%; 95% CI: 74% to 93%). Although eMBF in high-quality examinations was lower but not different between ischemic and infarcted segments (72.3 +/- 18.7 ml/100 ml/min vs. 73.1 +/- 31.9 ml/100 ml/min, respectively, p > 0.05), eMBV was significantly lower in infarcted segments compared with ischemic segments (11.3 +/- 3.3 ml/100 ml vs. 18.4 +/- 2.8 ml/100 ml, respectively; p < 0.01). CONCLUSIONS Compared with CMR, dynamic stress CT provides good diagnostic accuracy for the detection of myocardial perfusion defects and may differentiate ischemic and infarcted myocardium. (C) 2014 by the American College of Cardiology Foundation