Human Dosimetry Of The N-Methyl-D-Aspartate Receptor Ligand C-11-Gmom

The methylguanidine derivative C-11-GMOM (C-11-labeled N-(2chloro-3-thiomethylphenyl)-N9-(3-methoxyphenyl)-N9-methylguanidine) has been used successfully to quantify N-methyl-D-aspartate (NMDA) receptor binding in humans. The purpose of the present study was to estimate the C-11-GMOM radiation dose in healthy humans. Methods: After C-11-GMOM injection, 3 female and 2 male subjects underwent 10 consecutive whole-body PET scans in approximately 77 min. Seven source organs were defined manually, scaled to a sex-specific reference, and residence times were calculated for input into OLINDA/EXM software. Accepted tissue-weighting factors were used to calculate the effective dose. Results: The mean absorbed radiation doses in source organs ranged from 7.7 mu Gy.MBq21 in the brain to 12.7 mu Gy.MBq(-1) in the spleen. The effective dose (+/- SD) was 4.5 6 0.5 mu Sv.MBq(-1). Conclusion: The effective dose of C-11-GMOM is at the lower end of the range seen for other C-11-labeled ligands, allowing for serial PET scanning in a single subject.