Abstract: Imaging and Biodistribution of Injection of Iodine-131 Labeled Hepatoma Monoclonal Antibody HAb18 F(ab’)2 for Radioimmunotherapy in Human Body LI Yun-chun1, TAN Tian-zhi1, MO Ting-shu1, LU Wu-sheng2, DENG Hou-fu1, YANG Xiao-chuan1, LI Xiao2 (1.Department of Nuclear Medicine, West China Hospital, Sichuan University, Chengdu 610041,China; 2. Department of Surgery, West China Hospital, Sichuan University, Chengdu 610041,China) Abstract: Imaging and biodistribution of injection of iodine-131 labeled hepatoma monoclonal antibody HAb18 F(ab’)2 for radioimmunotherapy were assessed in vivo. Inclusion criteria, exclusion criteria and withdrawal criteria were drafted. 24 of cases with primary hepatocelluar carcinoma (PHC), strictly selected according to these criteria, were equally divided into three groups (8 of cases per group ). Every group was low dose group (administration dosage is 18.5 MBq/ kg human body ), middle dose group (administration dosage is 27.75 MBq/ kg human body ), high dose group (administration dosage is 37 MBq/ kg human body ), respectively. After relevant injection of Iodine-131 labeled hepatoma monoclonal antibody HAb18 F(ab’)2 for radioimmunotherapy, prepared using N-bromosuccinimide (NBS) labeling method, was administrated into the hepatic artery of every case. Every case was carried out whole body imaging at different time after administrating drug. The uptake of every tissue and the ratios of tumor tissue and non-tumor tissue (T/NT) were calculated using region of interest technique in order to observe the dynamic change of drug distribution in every tissue or tumor. The study of biodistribution showed that Iodine-131 labeled hepatoma monoclonal antibody HAb18 F(ab’)2 mainly accumulated in liver cancer and liver tissue and a small amount of that accumulated in other tissue at early stage, the radioactive concentration continuously increased in liver cancer and the uptake of radioactivity gradually decreased in liver with the extension of time. During the imaging time period ( 8 d ), T/NT ratios of other normal tissue besides liver were 1.04 -3.79, but T/NT ratios of liver gradually increased as the time increased and were 1.09 at d 8. PHC could specifically combine with Iodine-131 labeled hepatoma monoclonal antibody HAb18 F(ab’)2.