Myocardial Tomography with Technetium-99m-Tetrofosmin During Intravenous Infusion of Adenosine Triphosphate

The purpose of this study was to determine the biodistribution of 99mTc-tetrofosmin during intravenous infusion of adenosine triphosphate (ATP) and to evaluate the potential diagnostic value of myocardial tomography with 99mTc-tetrofosmin during ATP infusion for the detection of coronary artery disease. Myocardial 99mTc-tetrofosmin imaging with ATP infusion and coronary arteriography were performed on 65 patients with suspected coronary artery disease. ATP was infused intravenously at a rate of 0.16 mg/kg/min for 5 min, and 370 MBq of 99mTc-tetrofosmin was injected 3 min after the start of ATP infusion. Myocardial SPECT imags were obtained 60 min later. Then, 740 MBq of 99mTc-tetrofosmin was administered at rest, and myocardial SPECT was repeated. Regional uptakes of 99mTc-tetrofosmin were scored from 4, normal, to 0, no activity. Serial 5-min planar images were obtained in the anterior projection at 15, 30, 45 and 60 min after the 99mTc-tetrofosmin injection in 10 patients. Heart-to-lung and heart-to-liver count ratios were defined from the serial planar images. Adverse effects of ATP infusion were mild and transient. A heart-to-lung ratio after ATP infusion was high even at 15 min (3.40 +/- 0.33) and gradually increased with time. A heart-to-liver ratio after ATP was 0.53 +/- 0.40 at 15 min and increased with time. A heart-to-liver ratio reached 0.99 +/- 0.25 (p < 0.01) after 45 min and 1.32 +/- 0.36 (p < 0.01) after 60 min. The sensitivity and specificity for detecting coronary artery disease by myocardial SPECT with ATP were 89% (39/44) and 86% (18/21), respectively. This study shows the favorable biodistribution of 99mTc-tetrofosmin after intravenous infusion of ATP. A one-day imaging protocol of 99mTc-tetrofosmin tomography with ATP is feasible and has high diagnostic accuracy for coronary artery disease.