Preparation and biodistribution of 13N-ammonia

To study the synthetic method, quality control and biodistribution of 13N-ammonia, 13N-NO3- and 13N-NO2- were produced from water via the 16O (p, α)13N nuclear reaction with 16.5 MeV proton at 25-30 μA for 10-20 min and then converted to 13N-ammonia by the Devarda's alloy. Radiochemical purity was better than 95% as determined by HPLC and TLC. The biodistribution study of 13N-ammonia in mice indicated that the mean uptake of 13N-ammonia in myocardium was as high as 19.54%. At the first-pass time, the uptakes of myocardial and lung were (24.90 +- 1.82)% and (22.79 +- 1.94)%, respectively, and 92% radioactivity was cleared from blood. After injection, the radioactivity in each organ was significantly reduced at 1 min and was minimum at 5 min, but significantly increased at 10 min. The uptake of myocardium varied within the range of 11.34-29.24 during 1-30 min. High heart-to-liver and heart-to-lung ratios and rapid blood clearance were found. The results suggest that the Devarda's alloy method is a simple and rapid reducing means for the preparation of 13N-ammonia. 13N-ammonia was suitable for clinical regional blood perfusion imaging. PET imaging is suitable at 2-5 min after injection