@article{oai:repo.qst.go.jp:00046286,
 author = {Kawamura, Kazunori and Kimura, Yuichi and Yui, Joji and Wakizaka, Hidekatsu and Yamasaki, Tomoteru and Hatori, Akiko and Kumata, Katsushi and Fujinaga, Masayuki and Yoshida, Yuichirou and Ogawa, Masanao and Nengaki, Nobuki and Fukumura, Toshimitsu and Zhang, Ming-Rong and 河村 和紀 and 木村 裕一 and 由井 譲二 and 脇坂 秀克 and 山崎 友照 and 羽鳥 晶子 and 熊田 勝志 and 藤永 雅之 and 吉田 勇一郎 and 小川 政直 and 念垣 信樹 and 福村 利光 and 張 明栄},
 issue = {2},
 journal = {Nuclear Medicine and Biology},
 month = {Feb},
 note = {Introduction: We recently developed a selective 11C-labeled I2-imidazoline receptor (I2R) ligand, 2-(3-fluoro-4-[11C]tolyl)-4,5-dihydro-1H-imidazole ([11C]FTIMD). [11C]FTIMD showed specific binding to I2Rs in rat brains having a high density of I2R, as well as to I2Rs those in monkey brains, as illustrated by positron emission tomography (PET) and autoradiography. However, [11C]FTIMD also showed moderate
non-specific binding in rat brains. In order to increase the specificity for I2R in rat brains, we synthesized [11C]FTIMD with ultra-high specific activity and evaluated its binding.
Methods: [11C]FTIMD with ultra-high specific activity was prepared by a palladium-promoted cross-coupling reaction of the tributylstannyl precursor and [11C]methyl iodide, which was produced by iodination of [11C]methane using the single-pass method. Dynamic PET scans were conducted in rats, and the kinetic parameters were estimated.
Results: [11C]FTIMD with ultra-high specific activity was successfully synthesized with an appropriate level of radioactivity and ultra-high specific activity (4470+/-1660 GBq/mumol at end of synthesis, n=11) for injection. In the PET study, distribution volume (VT) values in all the brain regions investigated whether I2R expression was greatly reduced in BU224-pretreatead rats compared with control rats (29–45% decrease). Differences in VT values between control and BU224-pretreated rats using [11C]FTIMD with ultra-high specific activity were
greater than those using [11C]FTIMD with normal specific activity (17–34% decrease) in all brain regions investigated.
Conclusion: Quantitative PET using [11C]FTIMD with ultra-high specific activity can contribute to the detection of small changes in I2R expression in the brain.},
 pages = {199--206},
 title = {PET study using [ 11C]FTIMD with ultra-high specific activity to evaluate I2-imidazoline receptors binding in rat brains},
 volume = {39},
 year = {2012}
}