Automated synthesis of hypoxia imaging agent [18F]FMISO based upon a modified Explora FDG4 module

A new automated synthesis procedure of 1-H-1-(3-[F-18]fluoro-2-hydroxypropyl)-2-nitroimidazole ([F-18]FMISO), a specific hypoxia imaging agent with great significances for the noninvasive, dynamic hypoxia evaluation of cancer, was developed by modifying Explora FDG(4) module, a commercial [F-18]FDG production system, in this study. Its radiochemical synthesis was carried out via two sequent reaction steps, i.e. the nucleophilic displacement of labeling precursor 1-(2'-nitro-1'-imidazolyl)-2-O-tetrahydropyranyl-3-O-tosyl-propanediol (NITTP) with activated F-18- ion at 100 A degrees C for 8 minutes, and the following hydrolysis with 1M HCl at 100 A degrees C for 5 minutes and neutralization with 1M NaOH. Two-pot reaction with two independent separations was adopted to assure the good separation of final product via solid phase extraction (SPE) based upon combined Sep-pak cartridges instead of high performance liquid chromatography (HPLC). This fast, reliable preparation route of F-18-FMISO could complete within 50 minutes with about 55% of high radiochemical yield (with decay correction) and more than 98% of good radiochemical purity. The modified module could perform multiple runs of production of [F-18]FMISO.