Myocardial uptake of thallium-201 diethyldithiocarbamate (201T1-DDC) in cultured heart cells and in humans.

We assessed the feasibility of SPECT imaging with 201T1-diethyldithiocarbamate (201T1-DDC), a new cerebral blood flow tracer with little distribution, expecting to observe less extensive redistribution than with 201T1-chloride. Myocardial sections were obtained in three patients presenting with documented coronary artery disease and injected at peak exercise with 100 MBq 201T1-DDC. In two patients there was a clear redistribution phenomenon at four h after injection. In cultured myocardial cells of newborn rats, the uptake and washout of 201T1-chloride and 201T1-DDC were compared. The 201T1-DDC uptake was lower than 201T1-chloride (transmembrane gradients were respectively 89 +/- 10 and 4.1 +/- 0.2, mean +/- sem, n = 14, P less than 0.001). After 2 h washout in a T1 free medium, the retention of 201T1-chloride in the cells was 4% vs 19% for 201T1-DDC. It is concluded that although myocardial imaging is feasible with 201T1-DDC, this agent redistributes significantly with time.