TY - JOUR T1 - [18F]Flumazenil for central benzodiazepine receptor imaging and its comparison with [11C] in human brain JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 61P LP - 61P VL - 48 IS - supplement 2 AU - Ikuo Odano AU - Lars Farde AU - Per Karlsson AU - Andrea Varrone AU - Raisa Krasikova AU - Anu Airaksinen AU - Christer Halldin Y1 - 2007/05/01 UR - http://jnm.snmjournals.org/content/48/supplement_2/61P.4.abstract N2 - 205 Objectives: The central benzodiazepine receptors (BZRs) are distributed in the neocortex and cerebellum, and [11C]flumazenil ([11C]FMZ) is the most extensively used as PET radioligand. However, the 18F-labeled identical analog may be of advantage. We have demonstrated that [18F]flumazenil ([18F]FMZ) has high affinity and selectivity to central BZRs, and reported the first [18F]FMZ images last year. The aim of this study was to compare [18F]FMZ and [11C]FMZ images, and to estimate and compare binding parameters obtained by invasive and non-invasive methods. Methods: High SA of [18F]FMZ was synthesized. Both [18F]FMZ and [11C]FMZ PET studies were performed on six male normal volunteers with dynamic PET scanning for 90min after radioligands injection. Radioactive metabolites in plasma were determined with gradient HPLC. Applying compartment models (CPM), we analyzed both kinetics in the neocortices, cerebellum, pons and white matter. Binding potential (BP) values were obtained and compared with those obtained by reference tissue models using pons as reference region, which do not require an arterial input function. Results: The TACs of [18F]FMZ were better described by 3-CPM than 2-CPM in regions with highest and moderately high receptor density, but not in receptor-poor regions. BP values obtained by reference tissue models showed good agreement with those obtained by 3-CPM with K1/k2 fixed for pons. The BP values obtained by [11C]FMZ and [18F]FMZ were almost identical in all regions. The mean gray-to-white matter ratio of [18F]FMZ was lower than that of [11C]FMZ, but the ratios were more stable for 30 - 90min with smaller dispersion. The BP values obtained by [18F]FMZ during 90min showed good agreement with those obtained during 30 – 60min after injection. Conclusions: [18F]FMZ PET provides less variable BP values and less noisy images than [11C]FMZ. The reference tissue models using pons as reference region yielded reliable BP values without blood sampling. The data acquisition for 30 – 60min allows us to obtain high quality images and reliable binding parameters. [18F]FMZ is an ideal PET tracer and could play an important role, providing useful information in clinical studies. ER -