%0 Journal Article %A Huailei Jiang %A Aditya Bansal %A Mukesh K. Pandey %A Kah-Whye Peng %A Lukkana Suksanpaisan %A Stephen J. Russell %A Timothy R. DeGrado %T Synthesis of 18F-Tetrafluoroborate via Radiofluorination of Boron Trifluoride and Evaluation in a Murine C6-Glioma Tumor Model %D 2016 %R 10.2967/jnumed.115.170894 %J Journal of Nuclear Medicine %P 1454-1459 %V 57 %N 9 %X The sodium/iodide symporter (NIS) is under investigation as a reporter for noninvasive imaging of gene expression. Although 18F-tetrafluoroborate (18F-TFB, 18F-BF4−) has shown promise as a PET imaging probe for NIS, the current synthesis method using isotopic exchange gives suboptimal radiochemical yield and specific activity. The aim of this study was to synthesize 18F-TFB via direct radiofluorination on boron trifluoride (BF3) to enhance both labeling yield and specific activity and evaluation of specific activity influence on tumor uptake. Methods: An automated synthesis of 18F-TFB was developed whereby cyclotron-produced 18F-fluoride was trapped on a quaternary methyl ammonium anion exchange cartridge, then allowed to react with BF3 freshly preformulated in petroleum ether/tetrahydrofuran (50:1). The resultant 18F-TFB product was retained on the quaternary methyl ammonium anion exchange cartridge. After the cartridge was rinsed with tetrahydrofuran and water, 18F-TFB was eluted from the cartridge with isotonic saline, passing through 3 neutral alumina cartridges and a sterilizing filter. Preclinical imaging studies with 18F-TFB were performed in athymic mice bearing NIS-expressing C6-glioma subcutaneous xenografted tumors to determine the influence of specific activity on tumor uptake. Results: Under optimized conditions, 18F-TFB was synthesized in a radiochemical yield of 20.0% ± 0.7% (n = 3, uncorrected for decay) and greater than 98% radiochemical purity in a synthesis time of 10 min. Specific activities of 8.84 ± 0.56 GBq/μmol (n = 3) were achieved from starting 18F-fluoride radioactivities of 40–44 GBq. An avid uptake of 18F-TFB was observed in human NIS (hNIS)–expressing C6-glioma xenografts as well as expected NIS-mediated uptake in the thyroid and stomach. There was a positive correlation between the uptake of 18F-TFB in hNIS-expressing tumor and specific activity. Conclusion: A rapid, practical, and high-specific-activity synthesis of the NIS reporter probe 18F-TFB was achieved via direct radiofluorination on BF3 using an automated synthesis system. The synthesis of high-specific-activity 18F-TFB should enable future clinical studies with hNIS gene reporter viral constructs. %U https://jnm.snmjournals.org/content/jnumed/57/9/1454.full.pdf