Preparation of [Re-188]Rhenium sulfide suspension and its biodistribution following intra-tumor injection in mice

[Re-188]Rhenium sulfide suspension was prepared by the reaction of Na2S2O3 and KReO4 containing (NaReO4)-Re-188 in acid solution and assessed for its applicability in tumor treatment by the techniques of radioisotope interven tional therapy. The reaction conditions such as the concentration ratio of Na2S2O3, to KReO4, heating time, ultrasonic time were optimized. The radioc hemical yield of [Re-188]Rhenium sulfide suspension is more than 96% and in vitro stability studies demonstrated that more than 99% of the 188Re remai ned in sulfide form over a 72hrs period. The main particle size after vario us ultrasonic times is 1-5 mu m. [Re-188]Rhenium sulfide suspension was inj ected into tumors and the tumor-bearing mice were killed after some time to determine the retention of Re-188 in tumor and the leakage to different or gans by gamma counter. The mean retention percentages of Re-188 in tumors w ere 83.08 +/- 13.71%, 83.92 +/- 9.79%, 80.23 +/- 3.82% and 78.75 +/- 3.02% at Ih, 24, 48 and 72hrs respectively. After 72hrs the highest activity outs ide the tumors was in the liver, spleen and the kidneys. Our preliminary re sults indicated that [Re-188]Rhenium sulfide suspension may be an effective radiopharmaceutical for tumor treatment by the techniques of radioisotope interventional therapy.