A myocardial injury model is being used to survey compounds useful for diagnosis of acute infarction. Bone seeking ruthenium-97 compounds are being investigated. A generator, 52Fe/52mMn is being used to generate 21 minute manganese-52m for assessment of regional myocardial perfusion. The positron emitting 52mMn is used with a positron emission transaxial tomograph to image the distribution of radioactivity in the myocardium. Blood disappearance is rapid (clearance T1/2 less than 1.0 min.) and 3-4% localizes in the myocardium. An IND is being prepared and application to human studies will be instituted in the near future.