CLINICAL ROLE OF IN-111 ANTIMYOSIN IMAGING

Myocyte necrosis occurs in ischaemic, inflammatory and toxic heart diseases and can be detected by indium-111 antimyosin imaging. This allows a noninvasive evaluation of the site, extent and quantitation of the severity of myocardial necrosis. Simultaneous imaging of perfusion in patients with myocardial infarction allows the differentiation of necrosed and perfused areas and the varying degrees of mismatch and overlap, which has prognostic significance. In-111-antimyosin imaging is useful in the assessment of patients with unstable angina and in those for whom the diagnosis of infarction or unstable angina is not clear. In suspected myocarditis, a positive scan indicates the necessity for endomyocardial biopsy to confirm inflammation, whereas a negative scan makes the diagnosis of myocarditis unlikely. Antimyosin imaging is not useful as a marker of rejection in the 1 year post-transplant, but uptake after this period is associated with an increased rejection rate and is therefore an important tool in planning management strategies. Most patients on anthracycline treatment have demonstrable uptake, which is related to the cumulative dose and to the ejection fraction. Its role in this situation is as yet unclear. The use of new ligands and radioisotopes (Tc-99m) is likely to allow earlier imaging and produce improved quality.