Tissue damage after single high-dose intraoperative irradiation of the canine liver: Evaluation in time by means of radionuclide imaging and light microscopy

To establish the tolerance of liver tissue to single high-dose intraoperative irradiation, the histopathological changes in the canine liver after single high-dose intraoperative irradiation were investigated by means of radionuclide imaging and light microscopy, Intraoperative irradiation at doses of 0, 10, 20, 25 or 30 Gy was applied to a part of the liver of 25 beagles. Radionuclide imaging using Tc-99m-sulfur colloid was performed at several times during follow-up. Elective humane killing was done 3 months and 1, 2, 3 and 5 years after irradiation, Light microscopy was used to identify histopathological alterations. There was no morbidity or mortality during a maximal followup of 5 years. In 40% of the animals, a region of diminished uptake was observed at the irradiation site, The regions of diminished uptake of the radiopharmaceutical agent became smaller with time. Light microscopic examination revealed severe parenchymal fibrosis, liver cell atrophy, and bile duct proliferation at the irradiated area 1 to 2 years after irradiation. At 3 and 5 years, vascular changes with endothelial proliferation and focal arteriolar hyalinosis were observed, This study demonstrates that intraoperative irradiation of a part of the liver in the canine model can be applied safely. Light microscopy confirmed that histological damage was not always accompanied by diminished uptake of the radiopharmaceutical agent at the irradiation site. (C) 2000 by Radiation Research Society.