Primary experimental study on ¹⁸F-flurpiridaz synthesis and its myocardial perfusion imaging through PET/CT in normal miniature pigs

Objective: To explore the synthesis method of ¹⁸F-flurpiridaz and evaluate its ability for myocardial perfusion imaging (MPI) through PET/CT and bio-distribution in normal miniature pigs. Methods: ¹⁸F-Flurpiridaz was prepared through the substitution of the toluene sulfonate leaving group of tert-butyl-4-chloro-5(4-(2-methyl(sulfonyl-ethoxymethyl)phenyl)methyl) pyridazin-3-one followed by radiolabeling with ¹⁸F. The product was isolated and purified by high performance liquid chromatography (HPLC) non-gradient elution. PET/CT MPI was performed 10 min after intravenous injection of 37 MBq ¹⁸F-flurpiridaz in five normal miniature pigs, and PET/CT whole-body scans were performed 30 and 60 min after injection to observe the bio-distribution. Results: The total synthesis time (including HPLC separation) of ¹⁸F-flurpiridaz was approximately 50 min. The radiochemical yield was 40% (decay uncorrected), and the radiochemical purity was > 97% (after HPLC purification). MPI results demonstrated that the radioactive uptake primarily accumulated in heart muscles, whereas little radioactivity was distributed throughout the liver and lungs. Moreover, the image quality was good. The whole-body PET/CT data showed high uptake in heart muscles and kidneys, whereas the skeleton muscle only had little radioactive uptake. No evident accumulations of activity in other organs were observed. ¹⁸F-Flurpiridaz had higher retention in the myocardium 60 min after injection. Conclusion: The automatic synthesis of ¹⁸F-flurpiridaz is realized and optimized, which lays a foundation for its clinical application. (authors)