We assessed acute myocardial infarction (AMI) with cardiac rupture in an autopsy using magnetic resonance (MR) imaging in vitro and histological staining. Cardiac MR imaging in vitro generated high resolution images of myocardial thinning, rupture, and epicardial hemorrhage. High signal intensity (SI) on T(1) weighted images (WI) and low SI on T(2)WI of the rupture site corresponded with acute myocardial necrosis, edema, and hemorrhage. A rupture site rich in erythrocytes after AMI might affect SI on T(1) and T(2)WI in cardiac MR imaging.