Objective To assess the role of MR myocardial perfusion imaging (MRMPI) in detecting the viabilitive of myocardium in patient with old myocardial infarction (OMI) Methods MRMPI was performed in 47 patients suffering from old myocardial infarction with 1 5 T MR scanner Male 44, female 3, age ranged from 30 to 87 years with a mean of 61 years All patients were imaged during the first pass and delayed phase 5-30 min after injection of Gd DTPA 0 1 mmol/kg at 5 ml/s using IR turbo FLASH sequence Short axis images were acquired during the first pass, and both short axis and long axis images during delayed phase The left ventricular wall on short axis slice was divided into 8 segments A correlative study was carried out in 17 patients with the results of rest and stress 99m Tc SPECT scanning Results In 47 patients of old myocardial infarction, 29(61 7%) showed hypoenhancement during the first pass imaging (the SI was 50 20?7 45 percent of normal segment)and 46(97 9%) revealed delayed hyperenhancement(the SI was 491 0?197 26 percent of normal segment). For delayed hyperenhancement, 10(21 3%) was transmural ,15(31 9%) was nontransmural, and 21(44 7%) mixed, another one was normal 37 segments in 17 patients revealed to be nonviable by rest and stress 99m Tc SPECT, and the MRMPI all showed delayed hyperenhancement 116 viable segments on rest and stress 99m Tc SPECT, and no delayed hyperenhancement in 97 segments (83 6%) on MRMPI With the rest and stress 99m Tc SPECT as a standard of reference the sensitivity and the specificity of MRMPI were 100.0% and 83 6% respectively Conclusion The myocardial viability and nonviability as well as their severity and extent may be effectively evaluated with MRMPI in patients with OMI