Numerical Simulation And Experiment Research Of Microwave Ablation Combined With Liquid Perfusion In Porous Liver

Hepatocellular carcinoma(HCC)is the most common malignant tumor,which is a serious threat to human life and health.Microwave ablation with its high thermal efficiency,high safety,stable treatment and other advantages of clinical treatment of liver cancer became one of the important means.However,microwave ablation still has some defect for the treatment of large liver tumors(diameter> 3cm),single needle ablation is difficult to completely damage the tumor cells.In order to improve the shortcomings in the treatment of large tumors,and the method of liquid perfusion combined with microwave ablation can be used.Up to now,there is no theoretical data has shown that combined ablation can effectively expand the ablation area.Simultaneously because of the liver physiological structure,it can be used as a porous media model for simulation calculation.This paper used the finite element software to do simulation for microwave ablation combined with liquid perfusion.The results have shown that the combination of liquid perfusion microwave ablation could effectively expand the ablation area to achieve the purpose of treating large tumors of liver,and then it verified the authenticity of simulation data in vitro experiment.The research contents are as follows:1.Feasibility of liver as a porous media model in microwave ablation simulation calculations.The establishment of the liver model can be divided into two models,namely the liver as a biological tissue model and porous media model.The three-dimensional liver ablation model was established by using the biological tissue model,and the coupling calculation of electromagnetic field-temperature field was carried out.The power of ablation was set to 40 W,60W,80 W,and the time of ablation was set to 300 s.When the liver was used as the porous medium,the porosity of the liver was set to 0.05,0.1 and 0.15 respectively,and the blood flow velocity was set to 0.4cm/s and 2 cm/s respectively.The effects of ablation power,liver porosity,liver blood flow velocity on ablation,and the feasibility of the liver as a porous medium were analyzed by comparing the four parameters of transverse diameter,longitudinal diameter,area and volume of the temperature field after ablation.2.Simulation of microwave ablation combined with liquid perfusion in porous liver.Set up three-dimensional structure of porous media ablation model and perfusion type microwave antenna model,ablation power was set to 40 W and 60 W.The time of ablation was set to 600 s,the porosity of the liver was set to 0.05,and the blood flow velocity was set to 0cm/s(Compared with in vitro experiment)The injection of liquid was 0.9% saline and anhydrous ethanol,and the injection capacity was 10 ml and 20 ml respectively.At the same time,we set a group of non-injectable liquid groups as control group.The influence of the liquid injection on ablation temperature field was analyzed by comparing the transverse diameter,longitudinal diameter,area,volume and aspect ratio of the temperature field obtained after the ablation.3.Vitro experimental study of microwave ablation combined with liquid perfusion in the liver.The power of ablation was 40 W,60W,the time was set to 600 s,the injection liquid were 0.9% saline,anhydrous ethanol,and the liquid injection capacity was 10 ml,20ml,and a non-injected liquid group was set up as a control group.The influence of the liquid injection on the ablation temperature field was analyzed by comparing the transverse diameter,longitudinal diameter,area,volume and aspect ratio of the temperature field obtained after the ablation.These data were compared with the simulation.The results show:1.When considering the liver as a porous medium model,simulation results have shown that the liver porosity increased from 0.05 to 0.15,the ablation area of the volume decreased by 2.92%;liver blood flow increased from 0.4 cm/s to 2cm/s,and the volume of ablation area decreased by 0.3%,which indicated that change of the ablation area of the volume with the porosity and blood flow velocity is not obvious.2.The results of simulation of microwave ablation combined with liquid perfusion have shown that increasing rate of volume was 31.69%-125.29% and the transverse diameter increased from 2.81 cm to 4.11 cm with the increase of ablation power(40W to 60W)and injection capacity(10ml to 20ml)when the liquid was saline.When the liquid was anhydrous ethanol,the increasing rate reached 69.5%-144.4% and the transverse diameter enlargement to 4.06 cm.3.The results of vitro experiment have shown that increasing rate of volume was 49.01%-61.79% and the transverse diameter increased from 4.43 cm to 5.35 cm with the increase of ablation power and injection capacity when the liquid was saline.With the anhydrous ethanol injection,the rate reached 64.42%-152.29% and the transverse diameter enlargement to 7.07 cm.In this paper,the feasibility of the liver as a porous media model was verified by microwave ablation combined with liquid perfusion and the theoretical basis was provided for the combined ablation to expand the ablation area.