Resting Cardiac 64-MDCT Does Not Reliably Detect Myocardial Ischemia Identified by Radionuclide Imaging

Abstract

CT myocardial perfusion imaging is an emerging diagnostic modality that is under intensive study but not yet widely used in clinical practice. The purpose of this study is to evaluate the performance of resting 64-MDCT in revealing ischemia identified on radionuclide myocardial perfusion imaging (MPI). We retrospectively identified 35 patients (20 women and 15 men; mean age, 52 years) with myocardial ischemia found on MPI who underwent retrospectively gated CT within 90 days of MPI. Myocardial perfusion on CT was evaluated using both a visual (n = 35) and an automated (n = 34) method. For the visual method, myocardial segments were evaluated qualitatively in systole and diastole. For the automated method, subendocardial perfusion of the standard 17 American Heart Association segments was measured using a commercially available tool in both systole and diastole. Differences between systolic and diastolic perfusion were computed. Five hundred eighty myocardial segments were evaluated, 152 of which were ischemic on MPI. Visual analysis had a sensitivity of 16% (24/152), specificity of 92% (393/428), positive predictive value of 40% (24/60), and negative predictive value of 75% (392/520) in systole, and a sensitivity of 18% (27/152), specificity of 89% (382/428), positive predictive value of 37% (27/73), and negative predictive value of 75% (382/507) in diastole, as compared with MPI. There was no significant difference in subendocardial perfusion between ischemic and nonischemic segments by the automated method. There was no significant difference in CT perfusion between patients with and without obstructive coronary artery disease on CT angiography using the visual or automated methods. Resting 64-MDCT is unsuitable for clinical use in revealing ischemia seen on MPI.