@article{oai:repo.qst.go.jp:00048388,
 author = {Mori, Wakana and Takei, Makoto and Furutsuka, Kenji and Fujinaga, Masayuki and Kumata, Katsushi and Muto, Masatoshi and Ohkubo, Takayuki and Hashimoto, Hiroki and Tamagnan, Gilles and Higuchi, Makoto and Kawamura, Kazunori and Zhang, Ming-Rong and 森 若菜 and 武井 誠 and 古塚 賢士 and 藤永 雅之 and 熊田 勝志 and 武藤 正敏 and 大久保 崇之 and 橋本 裕輝 and 樋口 真人 and 河村 和紀 and 張 明栄},
 journal = {Nuclear Medicine and Biology},
 month = {Oct},
 note = {Introduction: 2-(2-(3-(4-(2-[18F]Fluoroethoxy)phenyl)-7-methyl-4-oxo-3,4-dihydroquinazolin-2-yl)ethyl)-4-isopropoxyisoindoline-1,3-dione ([18F]MNI-659, [18F]1) is a useful PET radiotracer for imaging phosphodiesterase 10A (PDE10A) in human brain. [18F]1 has been previously prepared by direct [18F]fluorination of a tosylate precursor 2 with [18F]F-. The aim of this study was to determine the conditions for the [18F]fluorination reaction to obtain [18F]1 of high quality and with sufficient radioactivity for clinical use in our institute. Moreover, we synthesized [18F]1 by [18F]fluoroethylation of a phenol precursor 3 with [18F]fluoroethyl bromide ([18F]FEtBr), and the outcomes of [18F]fluorination and [18F]fluoroethylation were compared. 
Methods: We performed the automated synthesis of [18F]1 by [18F]fluorination and [18F]fluoroethylation using a multi-purpose synthesizer. We determined the amounts of tosylate precursor 2 and potassium carbonate as well as the reaction temperature for direct [18F]fluorination.
Results: The efficiency of the [18F]fluorination reaction was strongly affected by the amount of 2 and potassium carbonate. Under the determined reaction conditions, [18F]1 with 0.82 ± 0.2 GBq was obtained in 13.6 ± 3.3 % radiochemical yield (n = 8, decay-corrected to EOB and based on [18F]F-) at EOS, starting from 11.5 ± 0.4 GBq of cyclotron-produced [18F]F-. On the other hand, the [18F]fluoroethylation of 3 with [18F]FEtBr produced [18F]1 with 1.0 ± 0.2 GBq and in 22.5 ± 2.5 % radiochemical yields (n = 7, decay-corrected to EOB and based on [18F]F-) at EOS, starting from 7.4 GBq of cyclotron-produced [18F]F-. Clearly, [18F]fluoroethylation resulted in a higher radiochemical yield of [18F]1 than [18F]fluorination.
Conclusion: [18F]1 of high quality and with sufficient radioactivity was successfully radiosynthesized by two methods. [18F]1 synthesized by direct [18F]fluorination has been approved and will be provided for clinical use in our institute.},
 pages = {12--18},
 title = {Comparison between [18F]fluorination and [18F]fluoroethylation reactions for the synthesis of the PDE10A PET radiotracer [18F]MNI-659},
 volume = {55},
 year = {2017}
}