Accumulation of gallium-67 in regions of acute myocardial infarction

The radionuclide gallium-67 has been shown to accumulate in a variety of inflammatory and neoplastic lesions, thereby permitting Identification of these abnormalities by radioisotope imaging. We have found that ⁶⁷Ga also accumulates selectively in recently infarcted myocardium. Acute myocardial infarction was induced in dogs by ligation of the left anterior descending coronary artery, then ⁶⁷Ga (3 to 4 mc) was injected intravenously. Hearts were removed 24 hours later, and isotope localization was evaluated by an Anger camera and by autoradiography. In five of eight dogs, ⁶⁷Ga was found to accumulate preferentially in regions of visible infarction. Tissue creatine phosphokinase (CPK), measured in four of the five dogs, was greatly reduced and white blood cell infiltration was intense in the infarcted region. The infarcts of three dogs without preferential ⁶⁷Ga uptake showed lesser degrees of CPK reduction and white blood cell infiltration. Localization of ⁶⁷Ga in regions of acute myocardial infarction was also demonstrable by scanning intact, closed chest dogs. Hearts of two animals with transient (20 minutes) ischemia showed neither ⁶⁷Ga accumulation nor decreased CPK. Thus, ⁶⁷Ga localization discriminates infarcted from normal or only transiently ischemic myocardium. Unlike potassium and its analogs, ⁶⁷Ga scanning does not depend on resolution of "cold" areas nor is it likely to introduce ambiguities due to flow limitation of isotope delivery. For these reasons ⁶⁷Ga may prove particularly useful in the imaging of acute myocardial infarction in man.