Binding of 5-(2'-[18F]fluoroethyl)flumazenil to central benzodiazepine receptors measured in living baboon by positron emission tomography.
5-(2'-[18F]Fluoroethyl)flumazenil ([18F]FEF), a fluorine-18-labeled analogue of the benzodiazepine antagonist flumazenil, was evaluated for use with positron emission tomography (PET). PET imaging of a baboon after i.v. injection of [18F]FEF showed that the radiofluorinated ligand rapidly localized in vivo within benzodiazepine receptor-rich cerebral tissues, and that selective disposition was retained for over 2 h. Coinjection of unlabeled flumazenil (0.55 mg/kg i.v.) abolished the heterogeneous cerebral distribution of the tracer; receptor-specific uptake was reduced by approximately 95%. The fluorinated benzodiazepine antagonist was degraded in vivo only to polar radiometabolites that do not cross the blood-brain barrier. [18F]FEF has advantages over existing PET radiopharmaceuticals, and is a promising radioligand for non-invasive evaluation of central benzodiazepine receptor binding in vivo.
Moerlein
S M
SM
Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110.
Perlmutter
J S
JS
D000818:Animals; D001923:Brain Chemistry; D005442:Flumazenil / Q000031:analogs & derivatives* / Q000378:metabolism; D005462:Fluorine Radioisotopes; D008297:Male; D010215:Papio; D011963:Receptors, GABA-A / Q000032:analysis*; D014055:Tomography, Emission-Computed
D005462:Fluorine Radioisotopes; D011963:Receptors, GABA-A; C077354:5-(2'-fluoroethyl)flumazenil; D005442:Flumazenil