Biodistribution and radiation dosimetry in humans of [11C]FLB 457, a positron emission tomography ligand for the extrastriatal dopamine D2 receptor

Purpose[11C]FLB 457, a radioligand with very high affinity and selectivity for dopamine D2/3 receptors, is used to measure receptor binding in extrastriatal regions showing low density of the receptors. The purpose of this study was to estimate the whole-body biodistribution of radioactivity and the radiation absorbed doses to organs after intravenous injection of [11C]FLB 457 in healthy human subjects.MethodsWhole-body images were acquired for 2 h after an injection of [11C]FLB 457 in six healthy humans. Radiation absorbed doses were estimated by the MIRD scheme implemented in OLINDA/EXM 1.1 software.ResultsOrgans with the longest residence time were the liver, lungs, and brain. The organs with the highest radiation doses were the kidneys, liver, and pancreas. The effective dose delivered by [11C]FLB 457 is 5.9 μSv/MBq, similar to those of other 11C-labeled tracers.ConclusionsThis effective dose would allow multiple scans in the same individual based on prevailing maximum recommended-dose guidelines in the USA and Europe.