99mTc-labeled colchicine for tumor imaging using DTPA as bifunctional chelating agent

For the purpose to develop novel 99mTc-labeled tumor imaging agents with SPECT, colchicine (CHC) was directly labeled by 99mTc using diethylene triamine pentacetate acid (DTPA) as bifunctional chelating agent. Trimethylcolchicinic acid, derivatived from colchicine, was conjugated to DTPA to get the new ligand DTPA-CHC, which was labeled by 99mTc in the presence of SnCl2 as reducing agent. The radiochemical purity of the 99mTc-DTPA-CHC complex was over 90 %. It had good hydrophilicity and was stable at room temperature. The high initial tumor uptake with moderate retention, good tumor/muscle ratios and satisfactory scintigraphic images highlighted the potential of 99mTc-DTPA-CHC for tumor imaging.