RESUMO
Objective This study compares a dual-freeze protocol with a triple freeze protocol for hepatic cryoablation in the Tibetan pig model.Method Cryoablation with a dual-(10-5-10-5 min)and triple-freeze (5-5-5-5-10-5 min) protocol for the normal livers of 9 Tibet pigs was performed under exposed operation.Temperature changes of cryoprobes and diameter changes of iceballs were measured during the ablation,and seven days later the pathological changes of cryozones were reviewed and the surface and depth cryolesions were measured.Results Compared with cryoablation with two freeze-thaw cycles,there was a greater iceball diameter for cryoablation by three freeze-thaw cycles.Also,seven days after cryosurgery,there were similar surface and deep cryolesions in dual-and triple-freeze protocols.Pathologically,the triple freezing protocol was associated with a longer zone of complete necrosis.Conclusions With the same freezing time (20 min),the triple-freeze protocol may become a more powerful liver-ablation method in cryosurgical application.