Initial Human PET Studies of Metabotropic Glutamate Receptor Type 1 Ligand 11C-ITMM

methoxy-N-methylbenzamide (11C-ITMM) is a potential radioli-gand for mapping metabotropic glutamate receptor type 1 (mGluR1) in the brain by PET. The present study was performed to determine the safety, distribution, radiation dosimetry, and initial brain imaging of 11C-ITMM in healthy human subjects. Methods: The multiorgan biodistribution and radiation dosimetry of 11C-ITMM were assessed in 3 healthy human subjects, who underwent 2-h whole-body PET scans. Radiation dosimetry was estimated from the normalized number of disintegrations of source organs using the OLINDA/EXM program. Five healthy human subjects underwent 90-min dynamic 11C-ITMM scans of brain regions with arterial blood sampling. For anatomic coregistration, T1-weighted MR imaging was performed. Metabolites in plasma and urine samples were analyzed by high-per-formance liquid chromatography. 11C-ITMM uptake was assessed quantitatively using a 2-tissue-compartment model. Results: Ther