In vitro and in vivo comparison of various physical ablation methods in pig liver

Objective To evaluate and compare embolization area following four different ablation techniques,including radiofrequency ablation,microwave ablation,high frequency induced thermotherapy(HITT)and laser ablation.Methods A total of 12 pigs were used in the in vivo studies and divided into 4 groups,corresponding to the four different ablation techniques.These four ablation techniques were also studied in pig liver in vitro under same conditions as in the in vivo experimental group for embolization.Liver cross section status and embolization area were observed and recorded.Results With in vitro radiofrequency ablation using a 3 cm radiofrequency needle electrode for 5.5,10 minutes,embolization areas were 2.12 cm×1.83 cm×2.07 cm and 2.59 cm×2.19 cm×2.19 cm.respectively.With the use of a 5 cm radiofrequency needle electrode for 5.5.10 minutes,the embolization areas were larger at 4.57 cm×2.58 cm×2.61 cm and 4.64 cm×2.70 cm×2.76 cm.respectively.For in vitro microwave ablation experiments,microwave power was adjusted to 80 W and ablation time set at 3,5,6,and,10 minutes.The corresponding embolization areas were 2.53 cm×1.84 cm × 1.23 cm,2.74 cm×2.08 cm×1.62 cm,2.85 cm×2.09 cm×1.59 cm and 3.38 cm×3.34 cm×1.77 cm.For the in vitro HITT experiments,ablation temperature was set at 85℃ for a duration of 5 or 10 minutes.The corresponding embolization areas were 2.53 cm×1.70 cm×0.90 cm and 3.03 cm×2.07 cm×1.53 cm,respectively.Finally,forin vitrolaser ablation experiments,the single needle embolization method was applied with power adjusted to 2.0 W and 2.5 W.The embolization areas were 0.95 cm×1.05 cm×0.85 cm and 1.05 cm×1.10 cm×0.90 cm.However.when the four needle capacitive coupling method was used with power adjusted to 10.0 W and 12.0 W,the embolization areas were 2.45 cm×1.45 cm×1.95 cm and 2.55 cm×1.55 cm×2.05 cm.For all in vivo experiments in using the four ablation techniques,the embolization areas in the pig livers were larger to varying degrees compared to the corresponding in vitro experiments.Conclusion These results provided data on the extent of embolization destruction using four different physical ablation methods,and may be useful in helping to identify an appropriate physical ablation technique in clinical therapy. Key words: Catheter ablation;  Laser coagulation;  Radiofrequency;  Microwave