Immunoscintigraphy with 111In antimyosin Fab

Monoclonal 111In antimyosin Fab is a marker for myocytes which have lost their membrane integrity. Because of the slow blood pool clearance of the radiopharmaceutical, imaging is usually started 24-48 h after intravenous injection of 74 MBq of the tracer. This long postinjection interval restricts its utilization in the primary diagnosis of acute myocardial infarction. However, antimyosin may help to differentiate between necrotic and viable myocardium in the subacute stage of incomplete myocardial infarction. Serial endomyocardial biopsy for early detection of transplant rejection after heart transplantation may be partially replaced or supplemented by antimyosin scintigraphy. The compound may facilitate the diagnosis of myocarditis. Other potential indications may be prognostic assessment of dilated cardiomyopathy, monitoring cardiotoxic side-effects of chemotherapeutics, recognition of cardiac contusion as well as diagnosis of rhabdo- and leiomyosarcoma. In specific clinical situations 111In antimyosin Fab immunoscintigraphy may provide valuable diagnostic information.