ORIGINAL RESEARCH n CARDIAC IMAGING Radiology: Volume 276: Number 3—September 2015 n radiology.rsna.org 715 Stress Myocardial Perfusion CT in Patients Suspected of Having Coronary Artery Disease: Visual and Quantitative Analysis—Validation by Using Fractional Flow Reserve 1 Dong Hyun Yang, MD, PhD Young-Hak Kim, MD, PhD Jae-Hyung Roh, MD Joon-Won Kang, MD, PhD Dongjin Han, PhD Joonho Jung, MS Namkug Kim, PhD Jung Bok Lee, PhD Jung-Min Ahn, MD, PhD Jong-Young Lee, MD, PhD Duk-Woo Park, MD, PhD Soo-Jin Kang, MD, PhD Seung-Whan Lee, MD, PhD Cheol Whan Lee, MD, PhD Seong-Wook Park, MD, PhD Seung-Jung Park, MD, PhD Tae-Hwan Lim, MD, PhD Purpose: To assess the diagnostic accuracy of stress myocardial perfusion computed tomography (CT) by using visual and quantitative analytic methods in patients with coronary artery disease, with fractional flow reserve (FFR) as a ref- erence standard. Materials and Methods: The institutional review board approved the study, and written informed consent was obtained from all patients. The diagnostic accuracy of myocardial perfusion CT was assessed for 75 patients who underwent myocardial perfu- sion CT and conventional coronary angiography with ref- erence to hemodynamically significant stenosis, defined as the presence of an FFR of 0.8 or less or an angiographical- ly severe (90%) stenosis. Results of quantitative analysis of myocardial perfusion CT data were compared with those of visual analysis by using areas under the receiver operating characteristic curve (AUCs). Results: Among the 75 patients and 210 epicardial arteries, 61 pa- tients (81%) with 86 arteries (41%) had hemodynamically significant stenosis. The per-patient sensitivity and spec- ificity of the visual assessment of myocardial perfusion CT data for all patients were 89% and 86%, respectively. At per-vessel analysis, the sensitivities and specificities, respectively, of myocardial perfusion CT were 80% and 95% for all vessels, 85% and 100% for 63 vessels with se- vere coronary calcification (defined as an Agatston score . 400), and 76% and 91% for 56 vessels in patients with multivessel disease. In severely calcified vessels, visual as- sessment of myocardial perfusion CT data in combination with CT angiography provided incremental value over CT angiography alone for the detection of myocardial ische- mia (integrated discrimination improvement index, 0.38; P , .001). Quantitative assessment of transmural perfu- sion ratio had a lower AUC than visual analysis of myocar- dial perfusion CT (0.759 vs 0.877, P = .002). Conclusion: Stress myocardial perfusion CT provides incremental value over CT angiography in patients with a high calcium score for the detection of myocardial ischemia as defined by FFR. q RSNA, 2015 Online supplemental material is available for this article. 1 From the Department of Radiology (D.H.Y., J.W.K., D.H., N.K., T.H.L.), Research Institute of Radiology, Department of Cardiology (Y.H.K., J.H.R., J.J., J.M.A., J.Y.L., D.W.P., S.H.K., S.W.L., C.W.L., S.W.P., S.J.P.), and Heart Institute, Department of Clinical Epidemiology and Biostatistics (J.B.L.), Asan Medical Center, University of Ulsan College of Medicine, Asanbyeongwon-gil 86, Seoul 138-736, South Korea. Received May 24, 2014; revision requested July 7; revision received November 25; accepted December 6; final version accepted January 20, 2015. Supported by the Korea Healthcare Technology Research and Development Project, Ministry of Health and Welfare, Republic of Korea (grants HI12C0630 and HI10C2020). Address correspon- dence to Y.H.K. (e-mail: mdyhkim@amc.seoul.kr). q RSNA, 2015 Note: This copy is for your personal non-commercial use only. To order presentation-ready copies for distribution to your colleagues or clients, contact us at www.rsna.org/rsnarights.