Preparation and biodistribution of rhenium-188 ECD/Lipiodol in rats following hepatic arterial injection

Radiolabeled Lipiodol has routinely been used in hepatoma therapy. In this article an attempt to develop a new 188Re-ECD/Lipiodol radiopharmaceutical, in which the chelating agent ECD (ethyl cyteinate dimer), is the constituent of the known brain perfusion agent 99mTc-ECD, and an evaluation of its stability and biodistribution in rats with hepatic tumors is presented. First, 188Re-ECD was prepared in a vial, followed by extraction with Lipiodol to get the final product, 188Re-ECD/ Lipiodol. The optimal labeling conditions for 188Re-ECD were: (1) tartaric acid which is better than EDTA as a weak chelating agent; and (2) 15 mg of SnCl2, as the reducing agent, and 5-10 mg of tartaric acid in each vial had a better labeling yield. The radiochemical purity of 188Re-ECD/Lipiodol was more than 94%. Twenty-four male Sprague-Dawley rats with liver tumors were sacrificed at 1, 24, and 48 h (eight rats each time) after an injection of approximately 7.4 MBq of 188Re-ECD/ Lipiodol via the hepatic artery. The radioactivity in the liver tumor is significantly high following therapeutic arterial injection, and relatively low in other organs including the bone, spleen, brain, thyroid, stomach, muscle, blood, and testis throughout this study. In conclusion, the new preparation of 188Re-ECD/Lipiodol is a candidate agent for the treatment of liver cancer. ? 2004 Elsevier Inc. All rights reserved.