6-[Fluorine-18]Fluorodopamine pharmacokinetics and dosimetry in humans

PET scanning after injection of 6-[18F]fluorodopamine visualizes tissue sympathetic innervation. Organ dosimetric estimates for 6-[18F]fluorodopamine have relied on studies of rats and dogs and on literature about the fate of other radiolabeled catecholamines. This report uses empirical clinical findings in healthy volunteers to refine and extend these estimates. Thoracic PET scanning was conducted and arterial blood and urine samples were obtained after intravenous injection of 6-[18F]fluorodopamine into 10 normal volunteers. The main target organs for 6-[18F]fluorodopamine-derived radioactivity were the wall of the urinary bladder (3.3 rem for a 4-mCi dose and 3.31-hr voiding interval) and the kidneys (2.9 rem for a 4-mCi dose) due to urinary excretion of radioactive metabolites of [18F]-6F-DA. The estimates were about one-fourth those predicted from studies of laboratory animals. At administered doses required to visualize the left ventricular myocardium in humans, a 6-[18F]fluorodopamine injection produces acceptable absorbed radiation doses, with the highest doses to the urinary collecting system. 22 refs., 2 figs., 5 tabs