STUDIES ON THE NEW ~(99)Tc~m-LABELLED RENAL IMAGING AGENTS Ⅱ. SYNTHESIS OF ~(99)Tc~m-MAG_2 AND IMAGING COMPARISON WITH ~(99)Tc~m-MAG_3 AND ~(99)Tc~n-DTPA

Changing the length of peptide chain, a new ligand,B_2-MAG_2 (benzoylthioacetyl diglycine), was synthesized. The effects of the pH value, reaction temperature and reaction time on the formation of ~(99)Tc~m-MAGa were studied and the preparation procedure with the complexing yield up to 98％ was established. The results on rabbits showed that both imaging quality and excretion rate of ~(99)Tc~m-MAG_2 were more superior to those of ~(99)Tc~m-DTPA (diethylenetriamine pentaacetate), which is currently used for renal imaging in clinic, while slightly inferior to ~(99)Tc~m-MAG_3 (mercaptoacetyl triglycine).