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

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