Quantification of myocardial blood flow using dynamic myocardial perfusion computed tomography

Abstract Background Cardiac CT angiography (CCTA) remains a limited method for evaluating the physiologic significance of coronary stenosis. On the other hand, dynamic techniques for evaluating myocardial perfusion imaging (MPI) allow quantification of myocardial blood flow (MBF) which may improve identification of hemodynamically relevance of luminal stenosis. Objective the purpose of this study was to determine the feasibility of vasodilator-stress CT-based dynamic MPI (CT-dMPI) for regional and global quantitively measurements of MBF for the identification of hemodynamically significant coronary stenosis. Materials and methods CCTA and CT-dMPI of 43 patients with chest pain were evaluated for the presence of coronary stenosis associated with perfusion defects and abnormal values of MBF (34 men and nine women; mean age, 60.9±12.9 years). Global MBF was quantified according to CT-dMPI and MBF values of normal and abnormal per-vessel territory (LAD, LCx and RCA) were correlated to the presence or not of coronary artery stenosis at CCTA. The relative MBF (rMBF) was calculated per vessel territory as the maximum coronary MBF divided by the reference MBF. Results In subjects without coronary plaques (Group I) the mean value of global MBF was 117.7±19.4 mL/100 mL/ml; LAD maximum blood flow was 130.9±9.7 mL/100 mL/ml; LCx maximum blood flow was 123.1±10.7 mL/100 mL/ml; RCA maximum blood flow was 128.1±7.3 mL/100 mL/ml; In patients without anatomically significant coronary stenosis or perfusion defects (Group II, 1%-69%) the mean value of global MBF was 127.5±26.2 mL/100 mL/ml; LAD maximum blood flow was 145.7±8.27 mL/100 mL/ml; LCx maximum blood flow was 134.5±8.1 mL/100 mL/ml; RCA maximum blood flow was 144.8±78.9 mL/100 mL/ml; In patients with significant stenosis (70%) the mean value of global MBF was 104.2±25.2 mL/100 mL/ml; LAD maximum blood flow was 110.4±7 mL/100 mL/ml; LCx maximum blood flow was 80.1±6.8 mL/100 mL/ml; RCA maximum blood flow was 92.7±5.9 mL/100 mL/ml; The median relative MBF was 0.73 for Group III and 0.93 for Group I and II. CT-dMPI demonstrated a sensitivity, specificity, PPV, NPV, and accuracy for the detection of significant stenosis of 70% (Group III) 82%, 100%, 100% and, 94%. Conclusions vasodilator-stress CT-based dynamic MPI (CT-dMPI) for regional and global quantitively measurements of MBF is feasible and the findings correlate with the visual assessment of the presence of coronary artery stenosis at CCTA. CT-dMPI might improve the diagnostic accuracy for identifying flow-obstructing stenosis compared with CCTA alone.