[Clinical trial of 111In-antimyosin antibody imaging: (1). Assessment of tracer kinetics and imaging time].

The human clinical trial of 111In-antimyosin antibody was performed in 20 patients with various cardiac disorders to assess its safety and tracer kinetics and to determine the optimal imaging time. There were no side effects derived from this tracer after its administration. The skin test and the antimurine antibody were both negative in any patient. The radiation dose to the kidney (3.6 rad) and to the whole body (0.36 rad) was acceptable. The half life of the blood clearance was 6.3 hours (fast component) and 25.8 hours (slow component) with the relatively high retention of blood activity at 24 hours (21%) and at 48 hours (11%). The planar images at 24 hours after the tracer administration in 4 patients showed high residual blood-pool activity without delineating significant myocardial uptake, while the images at 48 hours clearly demonstrated the presence or absence of discrete myocardial uptake. However, 2 patients showed significant residual blood-pool activity at 48 hours after the injection which needed 72 hour delayed scan in order to identify the myocardial uptake. In one patient, the single-photon tomography (SPECT) was useful to delineate the myocardial uptake from the residual blood-pool activity at 48 hours after the injection. Although this tracer provides an elegant technique for identifying myocardial necrosis, it needs 48 hours delayed scan and/or SPECT imaging because of relatively slow blood clearance.