IR-191M - DISTRIBUTION AND RETENTION IN A NIMAL-EXPERIMENTS

Ultrashort-lived tracer (191m)lr (T-1/2 = 4.92 s) can be obtained with a high yield from an Os-191/(191m)lr generator with a low Os-191 brea kthrough. It was eluated directly into the tail veins of Wistar rats. These animals were imaged dynamically (five frames/s) up to 40 s. The measurement was repeated five times on each animal. The whole-body ret ention and biodistribution of Os-191 was studied by sacrificing the ra ts at one and four days, respectively, after injection. The activity r etained was highest in the kidneys and the spleen, followed by the mus cles and the liver. These values indicate that the breakthrough is by no means dangerous and that investigations can be repealed immediately with a radiation exposure of no significance. Furthermore, all invest igations in the same animal were reproducible, suggesting that (191m)l r might be a good tracer for nuclear angiograms.