Synthesis and Evaluation of Fluorine-18 21-Fluoroprednisone as a Potential Ligand for Neuro-PET Studies

No-carrier-added fluorine-18-labeled fluoroprednisone (['8F]21-fluoroprednisone) was synthesized by tosylate displacement in 2%-8 % radiochemical yield in 80 min end of cyclotron bombardment (EOB), and its metabolism and distribution were investigated. After intravenous administration to rats, [18F]21-fluoroprednisonewas rapidly cleared from the blood and biotransformed into [18F]20-dihydro-21-fluoroprednisone. The suitability of [18F]21-fluorocorticoids for receptor imaging in humans with positron emitting tomography will depend on the synthesis of compounds with high binding affinity and low rate of carbonyl reduction at C-20. J NucÃ-Med 28:998-1005,1986 C'orticosteroids exert a variety of physiologic, bio chemical, and behavioral effects, modulate homeostatic mechanisms and, in high doses, exhibit major antiin-flammatory, antineoplastic, and antiedema potency. Steroids and their metabolites affect nerve cell activity in the brain (/), and fluctuations in regional brai