Detection of hemodynamically significant coronary artery stenosis: incremental diagnostic value of dynamic CT-based myocardial perfusion imaging.

PURPOSE To determine the feasibility of computed tomography (CT)-based dynamic myocardial perfusion imaging for the detection of hemodynamically significant coronary artery stenosis, as defined with fractional flow reserve (FFR). MATERIALS AND METHODS Institutional review board approval and informed patient consent were obtained before patient enrollment in the study. The study was HIPAA compliant. Subjects who were suspected of having or were known to have coronary artery disease underwent electrocardiographically triggered dynamic stress myocardial perfusion imaging. FFR measurement was performed within all main coronary arteries with a luminal narrowing of 50%-85%. Estimated myocardial blood flow (MBF) was derived from CT images by using a model-based parametric deconvolution method for 16 myocardial segments and was related to hemodynamically significant coronary artery stenosis with an FFR of 0.75 or less in a blinded fashion. Conventional measures of diagnostic accuracy were derived, and discriminatory power analysis was performed by using logistic regression analysis. RESULTS Of 36 enrolled subjects, 33 (mean age, 68.1 years ± 10 [standard deviation]; 25 [76%] men, eight [24%] women) completed the study protocol. An MBF cut point of 75 mL/100 mL/min provided the highest discriminatory power (C statistic, 0.707; P <.001). While the diagnostic accuracy of CT for the detection of anatomically significant coronary artery stenosis (>50%) was high, it was low for the detection of hemodynamically significant stenosis (positive predictive value [PPV] per coronary segment, 49%; 95% confidence interval [CI]: 36%, 60%). With use of estimated MBF to reclassify lesions depicted with CT angiography, 30 of 70 (43%) coronary lesions were graded as not hemodynamically significant, which significantly increased PPV to 78% (95% CI: 61%, 89%; P = .02). The presence of a coronary artery stenosis with a corresponding MBF less than 75 mL/100 mL/min had a high risk for hemodynamic significance (odds ratio, 86.9; 95% CI:17.6, 430.4). CONCLUSION Dynamic CT-based stress myocardial perfusion imaging may allow detection of hemodynamically significant coronary artery stenosis.