Self-expandable stent loaded with 125I seeds: feasibility and safety in a rabbit model

To evaluate technical feasibility and acute and subacute radiotolerance of a self-expandable stent loaded with (125)I seeds in the rabbit esophagus.

A self-expandable stent designed for esophageal application was made of 0.16mm nitinol wire and loaded with (125)I seeds (CIAE-6711). Twenty-seven stents with three different radioactive dosages (n=9 in each dosage group) were implanted in the esophagus of healthy rabbits, while nine stents alone were used as controls. The stents were perorally deployed into the esophagus under fluoroscopic guidance. Radiological follow-up included plain chest film, CT scan, and barium esophagography which were undertaken in all rabbits of each group at 2, 4, and 8 weeks, respectively, which were correlated to histopathological findings. The stented esophageal segments along with their adjacent tissues were harvested for histopathological examinations.

The stent was successfully deployed into the targeted esophageal segment in all rabbits. Neither (125)I seeds dislodged from the stent during the deployment, nor they did during the follow-up period. The greatest (16.2Gy) absorbed dose was found in the tissue 10mm from (125)I seeds at 8 weeks. Slight epithelial hyperplasia on the stent surface and submucosal inflammatory process developed at 2 weeks, which reached the peak at 8 weeks after the procedure. Significant thickness of the esophageal muscular layer was found at 8 weeks only in the groups with (125)I seeds. On radiologic follow-up, moderate strictures on both ends of the stents developed at 4 weeks and became severe at 8 weeks after the procedure in all groups.

Deployment of a self-expandable stent loaded with (125)I seeds is technically feasible and safe within the first 8 weeks. Acute and subacute radiotolerance of the treated esophagus and its adjacent tissues by (125)I seeds is well preserved in a healthy rabbit model.