99Tcm-diastereomeric dimercaptosuccinic acid complexes: comparison of their biodistribution

The biodistribution of two stereoisomeric 99Tcm complexes derived from diastereomeric dimercaptosuccinic acids (DMSA), 99Tcm-dl-DMSA and 99Tcm-meso-DMSA, was examined in sarcoma 180 tumour-bearing mice. The biodistribution pattern of meso-complex was not significantly different from 99Tc(V)m-DMSA, a new tumour imaging agent, while the dl-complex did not show the osteotropic property observed in meso- and 99Tc(V)m-DMSA complexes. The ratio of tumour to blood was superior for the 99Tcm-dl-DMSA (2.68) over the 99Tcm-meso-DMSA (1.25) at 3 h, and the ratio was reversed at 6 h, 3.13 to 4.28. The results indicate that dl-complex is of importance for the possible use in tumour imaging.