Biodistribution and radiation dosimetry in humans of [ super(11)C]FLB 457, a positron emission tomography ligand for the extrastriatal dopamine D sub(2) receptor

Purpose: [ super(11)C]FLB 457, a radioligand with very high affinity and selectivity for dopamine D sub(2/3) 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 [ super(11)C]FLB 457 in healthy human subjects. Methods: Whole-body images were acquired for 2 h after an injection of [ super(11)C]FLB 457 in six healthy humans. Radiation absorbed doses were estimated by the MIRD scheme implemented in OLINDA/EXM 1.1 software. Results: Organs 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 [ super(11)C]FLB 457 is 5.9 [mu]Sv/ MBq, similar to those of other super(11)C-labeled tracers. Conclusions: This effective dose would allow multiple scans in the same individual based on prevailing maximum recommended-dose guidelines in the USA and Europe.