Rapidly Automated Synthesis and Quality Control of ¹⁸F-Labelled Fluoromisonidazole

The rapid automatic synthesis of 1-H-1-(3-［¹⁸F］ fluoro-2-hydro-xylpropyl)-2-nitroimidazole (¹⁸F-FMISO) via two-pot procedure was adopted in modifying FDG module and taking 1-(2’-nitro-1’-imidazolyl)-2-O-tetra-hydropyranyl-3-O-tosyl-propanediol as labeling precursor in this study. The reaction time is 25 min. The product yield is (50.3±1.6)% with no decay correction, while (61.8±2.3)% with decay correction, radioactivity is 200-220GBq/L, average concentration is 2.1×10³ MBq. The radiochemical purity is above 98% by high-performance liquid chromatography and thin-layer chromatography, respectively. During the experiments of acute-toxicity and sterility tests, abnormal toxicity and the growing of bacteria don’t be found. There is not obvious variation in radiochemical purity after 6 h standing at room temperature or 48 h incubation in serum. ¹⁸F-FMISO was injected into mice through tail vein. The mice were sacrificed by cervical dislocation and biodistribution in mice was determined. Radiation dosimetry in humans was calculated on the basis of organ distribution in mice, so as to estimate the radiation safety. The estimation of the kidney in humans receives the highest dose of 24.6 μGy (all the calculation were based on injection 1 MBq of ¹⁸F-FMISO, the same below), the whole body receives the lowest dose of 8.49 μGy. The effective dose is estimated to be 20.5 pSv/Bq. Human radiation dosimetry can be performed by the mice biodistribution data and important data for clinical safe trial of ¹⁸F-FMISO are provided. At the same time, its bio-distribution shows that it can be used in clinical practice as a potential radiopharmaceutical for the non-invasive detection of hypexia in heart and lung tumors.