The effects of ¹⁸⁸rhenium-filled balloon dilation following bare stent placement in a rabbit oesophageal model

The objective of the study was to evaluate the efficacy of β-radiation using a rhenium-188-mercaptoacetyltriglycine (¹⁸⁸Re-MAG ₃)-filled balloon for preventing tissue hyperplasia secondary to bare stent placement in a rabbit oesophageal model. Immediately following bare stent placement in 30 rabbits, 10 underwent conventional contrast-filled balloon dilation (control group. Group I), and 20 underwent ¹⁸⁸Re-MAG ₃-filled balloon dilation, with half of these receiving 20 Gy (Group II) and half receiving 40 Gy (Group III) at a 1 mm tissue depth. Diameter percentage stenosis was calculated using oesophagography performed before sacrifice 6 weeks later. Gross and microscopic findings were obtained at both an area of untreated oesophageal tissue and a mid-stent area. Apoptosis and an apoptotic index in the mid-stent area were evaluated in two rabbits from each group. 13 rabbits survived the scheduled 6-week stent placement. Diameter percentage stenosis for Groups II and III was significantly lower than for Group I. The oesophageal mucosa showed nodularity in Group I and smoothness in Groups II and III. Oesophageal mucosal erythema (n=9) and perforations (n=10) were observed in Groups II and III only. Mid-stent epithelial layer thickness and muscularis propria destruction differed between the three groups (p<0.05). Apoptosis was increased and the apoptotic index was higher in Groups II and III than in Group I. In conclusion, ¹⁸⁸Re-MAG₃-filled balloon dilation was effective in preventing tissue hyperplasia secondary to bare stent placement, but at the cost of an increased risk of radiation-induced mucosal inflammation and perforation, in a rabbit oesophageal model. Apoptosis may be the mechanism underlying this irradiation-induced suppression of tissue hyperplasia.