Rapid and reproducible radiosynthesis of [ 18F] FHBG

9-(4-[ 18F] Fluoro-3-hydroxymethylbutyl) guanine ([ 18F] FHBG), an imaging agent for gene therapy using PET, was prepared in a one-pot, two-step synthesis. Microwave (MW) mediated nucleophilic fluorination of N 2, monomethoxytrityl-9-[4-(tosyl)-3-monomethoxytrityl-methylbutyl] guanine using no-carrier-added [ 18F] fluoride, followed by deprotection with hydrochloric acid and HPLC purification, gave [ 18F] FHBG. The radiochemical yield (decay corrected) was 12±5% (n = 35), the synthesis time was 55-60 min, and the radiochemical purity was >99%. The compound was used for lung imaging and was injected into Sprague-Dawley rats previously infected with the herpes simplex virus type 1 thymidine kinase (HSV1-tk) reporter gene. MicroPET imaging showed accumulation confined to the lungs.