Development of a low cost multipurpose system for F-18 labeled PET probe production

Objectives Automated synthesizer is useful for translational research of PET probes because it has advantages such as reproducibility production and workers exposure reduction. We have developed a flexible module system at low cost for the synthesis of PET probes using commercially available servomotors for miniature hobby robot tools. In last meeting, we reported the synthesis of [¹⁸F]fluoroacetate to confirm the usefulness of the system. In this study, we optimized the synthesis of 16β-[¹⁸F]fluoro-5α-dihydrotestosterone (FDHT) as another probe.

Methods The module was consisted of a 10 mL plastic syringe, seven plastic three-way valves and a heater unit. The additional unit was included two valves. The reactor was used a standard 10 mL vial and all wetted parts were utilized medical devices and disposable sterile materials. The FDHT synthesis was started from 16β-[[(trifluoromethyl) sulfonyl]oxy]-3,3-(ethylenedioxy) androstan-17-one in acetonitrile was heated at 110^oC for 10 min with dried [¹⁸F]fluoride. Then 1.5 mg of NaBH₄ in ethanol was added to the reacted solution. The hydrolysis was carried out using HCl for 10 min.

Results The reduction using NaBH₄ was completed in less than10 min. The hydrolysis was inadequacy using 0.1M HCl but it was accomplished using 1 M HCl. The radiochemical yield in the final product was 10% (decay corrected).

Conclusions The system helped the study of the optimum conditions for the synthesis and realized multi probe synthesis. Therefore, the convenient system may help the research of the PET probe development.