Dosimetric estimates for clinical positron emission tomographic scanning after injection of [18F]-6-fluorodopamine.
Positron emission tomographic (PET) scanning after systemic i.v. injection of fluorine-18-6-fluorodopamine ([18F]-6F-DA) is a method for visualizing and measuring regional sympathetic nervous system innervation and function. Based on results of preclinical studies of rats and dogs and on previous literature about the fate of injected tracer-labeled catecholamines, dosimetric estimates for clinical studies are presented here. After injection of 1 mCi of [18F]-F-DA, the radiation dose would be highest to the wall of the urinary bladder (1.40 rem/mCi), due to accumulation of radioactive metabolites of [18F]-F-DA in urine. Radioactivity also would accumulate in bile. Organs receiving the next highest dose would be the kidneys (0.9 rem/mCi) and small intestine (0.2 rem/mCi). The parenchymal radiation dose would be lowest in the brain, since there is an effective blood-brain barrier for circulating catecholamines. Radiation doses to all organs after administration of 1 mCi of [18F]-F-DA to humans would be less than 3 rem and, therefore, within current FDA guidelines.