Purpose: The purpose of the present study was to investigate the significance of each enhancement pattern of two-phase contrast-enhanced MDCT in reperfused acute MI with intracoronary physiology studies. Methods: First-onset acute MI patients were enrolled. After successful revascularization, intracoronary physiologic studies were performed with a Doppler wire. Two-Phase Contrast enhanced MDCT was taken within 3 days after PCI. The patterns of perfusion defects and late enhancement (LE) were classified into three groups. Group A = absence of early perfusion defect (ED) and absence or presence of LE without residual perfusion defect (RD), group B = presence of ED and presence of LE without RD, group C = presence of ED and presence of LE with RD. Results: 53 acute MI patients (group A, 9; group B, 20; group C, 24) were enrolled. The baseline and hyperemic average peak velocity of the group C were the lowest among 3 groups (24.2짹11.5 vs. 20.1짹6.9 vs. 13.5짹6.9 cm/sec, p=0.037; and 48.8짹16.7 vs. 37.1짹10.8 vs. 25.5짹10.8 cm/sec, p=0.018, respectively). Baseline and hyperemic microvascular resistance index of the group C were the greatest among 3 groups (3.16짹2.22 vs. 4.03짹1.94 vs. 5.86짹2.12 mmHg•cm-1•sec, p=0.036; and 1.53짹1.29 vs. 2.16짹1.64 vs. 2.99짹1.32 mmHg•cm-1•sec, p=0.030, respectively). The baseline and hyperemic diastolic deceleration time of the group C were the longest among 3 groups. (669짹262 vs. 519짹282 vs. 313짹152 msec, p=0.021; 751짹246 vs. 616짹269 vs. 363짹104, p=0.033, respectively). However, the 3 groups did not have any significant differences in CFR (2.02짹 0.64 vs. 1.85짹0.60 vs. 1.70짹0.55 p=0.060). Conclusions: RD in the delayed phase of Two-Phase Contrast enhanced MDCT corresponded to more severe myocardial necrosis with extensive microvascular damage than LE. LE might contain greater viable myocardium than RD.