We have anlayzed the polar maps of dipyridamole stress/rest Tc-99m-MIBI SPECT and compared the quantitated perfusion defects of dipyridamole stress polar map and the findings of coronary angiograraphy in 56 pateints with coronary artery diseases. We performed the same day dipyridamole stress-rest myocardial SPECT, reconstructed the polar maps according to Cedars-Sinai method and quantitated perfusion defects of total myocardium and the territory of each artery, comparing the polar maps of patients with normal files. Stenosis more than 50 percent was considered significant and myocardial ischemic score was calculated as summed score of percents of main coronary arteries. Positive concordance of myocardial SPECT with coronary angiography were 82.6% with left anterior descending artery(LAD), 85.7% with left circumflex artery(LCx) and 78.6% with right coronary artery(RCA). Perfusion defect of SPECT polar map and the stenosis of coronary artery showed the contingency phi of 0.55(p〈0.0001) with total atreries, 0.38(p=0.016) with LAD, 0.50(p〈0.0001) with LCx and 0.40 (p=0.007) with RCA. Dipyridamole stress percent defect of polar map was correlated with myocardial ischemic score with Spearman's rho of 0.47(p=0.001) in total arteries, 0.48(p=0.001) in LAD, 0.56 (p〈0.001) in LCx and 0.38(p=0.002) in RCA. These findings revealed that defect of the dipyridamole stress myocardial Tc-99m-MIBI SPECT and the percent extent of this defect were related with significant artery stenosis of individual arteries and the degree of stenosis. We thought that we could use the defects in the polar map of dipyridamole stress Tc-99m-MIBI SPECT for the quantification of myocardial perfusion decrease.