Preliminary studies for preparation of DMSA-V kit for labelling with 99mTc

Technetium-99m is the most useful radionuclide in diagnostic imaging procedures in Nuclear Medicine, more than 80 percent of radiopharmaceuticals are 99mTc-labeled compounds. The reason for such a position of 99mTc in clinical use is its favorable physical characteristics (half life of 6.02 h, gamma emission of low energy, 140 keV, and absence of particulated emission). 99mTc-DMSA(V) is used for the detection of medullary thyroid cancer and other soft tissue tumors. Other studies carried out by this compound include head and neck tumors, liver and skeletal metastases from breast carcinoma. The aim of this work is the development of a lyophilized DMSA-V kit for the one step labeling with 99mTc, and to compare it with the two steps labeling method performed by pH adjustment of a DMSA(III) kit. The radiochemical purity was evaluated by thin layer chromatography on silica gel (TLC-SG), developing with n-butanol/acetic acid/H2O (3:2:3) solvent, 99mTc- DMSA(III) stayed at the origin (Rf= 0), and 99mTc-DMSA(V) (Rf 0.7) migrated more slowly toward the solvent front than 99mTcO4-(Rf = 1). When developing with water, 99mTcO2 stayed at the origin and the other species migrated to the solvent front. The results so far showed good labeling yields of 99mTc-DMSA (V). (author)