A novel electrophilic synthesis and evaluation of medium specific radioactivity (1R,2S)-4-[F-18]fluorometaraminol, a tracer for the assessment of cardiac sympathetic nerve integrity with PET

(1R,2S)-4-[F-18]fluorometaraminoI (4-[F-18]FMR), a tracer for cardiac sympathetic innervation, was synthesized by electrophilic aromatic substitution. A trimethylstannyl precursor, protected with tert-butoxycarbonyl protecting groups, was radiofluorinated with high specific radioactivity [F-18]F-2. Specific radioactivity of 4-[F-18]FMR, in average 11.8 +/- 3.3 GBq/mumol, was improved 40-800-fold in comparison to the previous electrophilic fluorinations. The biodistribution of 4-[F-18]FMR in rat was in accordance with the known distribution of sympathetic innervation. 4-[(18)]FMR showed no metabolic degradation in left ventricle of rat heart, where the uptake was high, rapid and specific. (C) 2004 Elsevier Inc. All rights reserved.