title: High-yield automated synthesis of [18F]fluoroazomycin arabinoside ([18F]FAZA) for hypoxia-specific tumor imaging.
abstract: The aim of this study was to develop an efficient fully automated synthesis method to achieve a high radiochemical yield of [(18)F]FAZA with a small amount of precursor. A small cartridge containing 25mg of the QMA resin was prepared and evaluated to obtain [(18)F]F(-) in a small quantity of base (K(2)CO(3)), which might allow the use of a small amount of precursor. The labeling and hydrolyzing conditions for [(18)F]FAZA synthesis were also investigated manually. No-carrier-added [(18)F]F(-) was trapped on the small QMA cartridge and eluted with a mixture of Krytofix 222 (2.26 mg, 6.0 μmol) and K(2)CO(3) (0.69 mg, 5.0 μmol) in 70% MeCN (0.4 mL). The automated synthesis of [(18)F]FAZA was optimally performed with a modified NIRS original synthesis system for clinical use, by labeling 2.5mg (5.2 μmol) of the precursor in DMSO (0.4 mL) at 120°C for 10 min, and then by hydrolyzing the (18)F-labeled intermediate with 0.1M NaOH (0.5 mL) at room temperature for 3 min. Using the above condition, the [(18)F]FAZA injection was obtained with a high radiochemical yield of 52.4±5.3% (decay-corrected, n=8) within 50.5±1.5 min.
authors.affiliation: Radiopharmaceutical Production Team, Molecular Probe Group, Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, Japan. hayashik@riken.jp
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Hayashi
authors.forename: Kenji
authors.initials: K
authors.lastname: Furutsuka
authors.forename: Makot
authors.initials: M
authors.lastname: Takei
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Muto
authors.forename: Ryuji
authors.initials: R
authors.lastname: Nakao
authors.forename: Hatsumi
authors.initials: H
authors.lastname: Aki
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Suzuki
authors.forename: Toshimitsu
authors.initials: T
authors.lastname: Fukumura
mesh_terms: D001331:Automation; D015687:Cell Hypoxia; D005462:Fluorine Radioisotopes; D006801:Humans; D009369:Neoplasms / Q000175:diagnosis*; D009593:Nitroimidazoles
chemical_list: D005462:Fluorine Radioisotopes; D009593:Nitroimidazoles; C498052:fluoroazomycin arabinoside