TRANSLOCATION OF THOROTRAST IN THE BODY

To investigate whether there is a permanent translocation of Thorotrast in the body, the liver of male Lewis rats was removed 4 weeks after injection of Thorotrast (300 pi) and replaced by a donor liver. In half of the animals the spleen was removed as well. Measuring the Th-232 content in the donor liver at different times after implantation demonstrated a permanent transport of Th-232 into the surrogate organ. After 231 days a Th-232 depot of about 1.1 mg was found, representing about 3% of the total body burden. The additional removal of the spleen resulted in a significantly lower transport of Th-232 into the implanted liver. Histological examinations of the donated livers revealed increasing local concentration of Thorotrast granules, leading to the development of conglomerates. A comparable translocation of Thorotrast was verified in two humans who required liver transplantation more than 40 years after Thorotrast injection.