Technetium-99m antimyosin antibody (3-48) myocardial imaging: human biodistribution, safety and clinical results in detection of acute myocardial infarction.

Technetium-99m antimyosin (99mTc-AM) antibody imaging may have significant advantages over indium-111 antimyosin in clinical practice. The purpose of this study was to determine the human biodistribution, the safety profile and the sensitivity of 99mTc-AM (3-48) imaging in the detection of both Q-wave and non-Q-wave myocardial infarction (MI). Biodistribution and safety parameters were mainly determined in 12 normal healthy volunteers while 40 patients with proven MI (22 Q-wave, 18 non-Q-wave) were injected with 99mTc-AM (20-25 mCi) between 5 h and 7 days after the onset of acute chest pain. Three standard planar views were performed at 6 h and at 24 h post injection. Both sets of images were completed in 33 patients while two patients were imaged only at 6 h, three patients only at 18 h and one at 18 and 24 h. One patient was not imaged. Vital signs and ECG were recorded and blood samples for haematology, biochemistry and human antimurine antibodies (HAMA) and urinalysis were obtained in all volunteers and patients. No serious adverse reactions or side-effects attributable to 99mTc-AM have been reported. No volunteers or patients developed allergic reactions or significant increases in HAMA titres. Reading of 99mTc-AM imaging was performed by two blinded experienced observers. The sensitivity of 99mTc-AM in the detection of MI was 100% (21/21) for Q-wave and 83.3% (15/18) for non-Q-wave infarctions. The overall sensitivity was 92.3% (36/39). The three false-negative cases were inferoposterior MI. A certain degree of uptake focalization was seen in 26 out of 35 (74.2%) at 6 h. At 24 h, two patients (5.8%) did not show 99mTc-AM uptake while 22 (64.7%) showed intense focal uptake, seven (20.6%) moderate uptake and 3 (8.9%) slight uptake. It is concluded that 99mTc-AM (3-48) imaging is safe and shows high sensitivity in the detection of both Q-wave and non-Q-wave MI even with early imaging (6 h post injection). These promising results warrant further clinical investigation.