ABSTRACT
Objective To evaluate the tissue response to the covered metallic stent loaded with radioactive 125I seeds in normal rabbit esophagus.Methods Twelve rabbits were randomlv assigncd into 2 groups.A covered metallic stent loaded with three 125I seeds set in sheaths Was implanted into the esophagus of the rabbit from experimental group(22.2 MBq for each seed,n=6).The rabbits of control group were implanted with stent without 125I (n=6).Two rabbits from each group underwent esophagus X-ray examination to detect migration of the stent and the 125I seeds at 2,4 and 8 weeks after stent implantation,respectively.And the animals were then sacrificed to observe the changes in esophagus.Results No 125I seed migration Was found during and after the implantation of the stent.No esophageal perforation was observed.Two weeks after stent implantation,such mild lesions were observed in the middle of the esophagus in experimental group as slight epithelial hyperplasia and submucosal inflammation.At 4th week after stentimplantation,granulation and fibrosis were observed,which became more obvious at 8th week after the procedure.The injury of esophageal tissue opposite to the 125I seed Was significantly milder than that of the tissue exposed to 125I seed.In control group,esophagus adjacent to the middle of the stent WaS similar to normal tissue,with slight epithelial hyperplasia.However,both ends of the stent were covered with marked hyperplasia epithelium in both groups,and severe granulation and fibrosis could be observed.Conclusion The main pathological changes of esophagus wall adjacent to the 125I seed are granulation and fibrosis.No bleeding or perforation occurs.