Basic studies of various 99mTc-labelled renal agents and clinical application of 99mTc-malate

Various renal imaging agents that were reported in the past and a new agent, 99mTc-malate as well as99mTc-cystein acetazolamide complex were prepared using electrolysis and electrochemical methods. These were studied for their labelling efficiency. After animal experiments with selected 99mTc-compounds, 99mTc-malate proved to be sufficient for renal imaging with adequate concentration. 99mTc-malate differs from other renal imaging agents in the utilization of endogeneous metabolic product. The first half time of 99mTc-malate in humans is 17 minutes, on the average, and the urinary excretion rate of 99mTc-malate is 36+/-6.05% in 1 hour after intravenous administration, 44+/-3.41% in 2 hours and 50+/-5.62% in 3 hours. In our 40 clinical experiences of 99m-Tc-malate, most cases demonstrated quite clear renal images in the serial scintiphotos except cases whose serum creatinines were over 4.5 mg/dl.