Automated and efficient radiosynthesis of [18F]FLT using a low amount of precursor

IntroductionSince 1991 until now, many radiosyntheses of [18F]FLT have been published. Most of them suffer from side reactions and/or difficult purification related to the large amount of precursor necessary for the labeling step. A fully automated synthesis using only commercial and unmodified materials with a reduced amount of precursor would be desirable.MethodsWe first explored the possibility to elute efficiently [18F]fluorine from commercial and unmodified cartridges with various amount of base. Based on these results, 10 mg and 5 mg of precursors were used for the fluorination step. The best conditions were transposed in an automated process for a one pot two steps synthesis of labeled FLT.ResultsUsing commercial and non-treated carbonate form of QMA cartridges, we were able to elute quantitatively the [18F]fluorine with a very low amount of base (0.59 mg) and, with only 5 mg of precursor, to perform an efficient fluorination reaction with up to 94% incorporation of [18F]fluorine. The synthesis was fully automated and radiochemical yields of 54% (decay corrected) were obtained within a synthesis time of 52 minutes.ConclusionWe demonstrate that a fully automated and efficient radiosynthesis of [18F]FLT is feasible with only 5 mg of precursor. Compare to the present state of the art, our method provides high yields of pure [18F]FLT and is broadly adaptable to other synthesis automates.