The preparation of 99Tcm-GSA and its instant lyophilized kit for hepatic receptor imaging

The ligand GSA (diethylenetriamine pentaacetic acid-galactosyl-human serum albumin) was synthesized by introducing bifunctional chelator DTPA (diethylenetriamine pentaacetic acid) to human serum albumin (HSA) via DTPA anhydride first, and then coupling galactosyl units (2-imino-2-methoxyethyl-thio-galactose) to DTPA-HSA. GSA was labeled with 99Tcm by using SnCl2 as reductant and the labeling conditions of 99Tcm-GSA were optimized. Lyophilized kit of GSA was also developed for instant preparing of 99Tcm- GSA. The labeling yields in excess of 96% by using both of liquid and lyophilized labeling methods. Biodistribution of 99Tcm-GSA was investigated in both normal and liver-injury model mice. 99Tcm-GSA showed high liver uptake in normal mice (>70%ID·g-1 at 30 min after injection). The liver uptake in liver-injury model mice is lower than that of in nor- mal mice (P=0.0324). The promising biological properties of 99Tcm-GSA combined with the development of reliable and instant lyophilized GSA kit afford the opportunity of liver receptor imaging for routine clinical assessment of hepatocyte function. (authors)