99Tcm hydroxyethyl starch: a potential radiopharmaceutical for lymphoscintigraphy

The usefulness of 99Tcm hydroxyethyl starch (99Tcm HES) has been evaluated for visualization of lymphatic channels and lymph nodes. 99Tcm HES was prepared with a labelling efficiency higher than 95%. Its usefulness for imaging lymphatic channels and lymph nodes were compared to 99Tcm human serum albumin (99Tcm HSA), 99Tcm dextran (99Tcm DXT) and 99Tcm sulphur micro colloid (99Tcm SMC) in rabbits. 99Tcm HES showed a good visualization of lymphatic channels and lymph nodes and it had the highest clearance rate from the injection site (P less than 0.01). 99Tcm HES showed higher uptake by the nodes than 99Tcm DXT (P less than 0.001) at 90 min post injection. The concentration of 99Tcm HES in the lymphatic channels was higher than that of 99Tcm SMC at 90 min post injection (P less than 0.001). Preliminary studies of 99Tcm HES in humans provided high-quality lymphoscintigrams of the leg, and the pelvic and para aortic lymph nodes in less than 10 min post injection. In addition, partially and completely obstructed lymphatics could be differentiated from the normal one. Hence 99Tcm HES is a potential radiopharmaceutical for visualization of lymphatic channels and nodes.