Experimental Study On The Thermal Insulation Of In Situ Gel In The Microwave Ablation Of Liver Tissue Abutting The Stomach

Purpose:1、To study on the insulation effect of thermosensitive in situ gel duringmicrowave ablation;2、Experimental study on the safety and thermal insulation of gelwhen percutaneous microwave ablation of liver tissue neighboring gastrointestinal in New Zealand white rabbits.Materials and methods:1. In vitro experimental study: Four thermometry needle R1、R2、R3、and R4located in one side of the microwave electrode, the distance ofthermometry needle from the electrode is5mm、10mm、15mm、20mm, a thickness of5mm in situ gel film placed between R1and R2. Microwave ablation power50W,duration of action300seconds, repeated six times. Every30seconds to read R1、R2temperature，obtaining a temperature difference of the same point in time, drawingtemperature difference curve. Recording the temperature of the thermometry needlewhen the thermometry needle R1up to60℃.2. In vivo experimental study:32adultNew Zealand white rabbits, male or female,3to4months of age, weight2.4±0.1kgwere randomly divided into four groups (n=8). The experimental group1was injectedin situ gel solution10ml every one between the rabbits’ liver and the stomach wall.Experimental group2, injection of5%saline410±95ml. Control group without anyablation protection measures. Microwave output power of40W for300seconds, a totalof32ablation zones. Histopathological observation of each group of the stomach wallthe severity of thermal damage after ablation. In addition eight injection in situ gelsolution10ml each. Microwave ablation power of40W for300seconds. One day beforemicrowave ablation, postoperative3d,7d via the femoral vein pumping blood5ml,checking liver function and renal function.Results:1、In vitro experimental results: The maximum temperature differencesbetween the thermometry needle R1and R2is31.3±0.1℃. When the thermometryneedle R1up to60℃,R2、R3、R4temperature were29.8±0.1℃、18.6±0.3°C、18.1±0.1℃. The thermometry needle R2reached a maximum temperature of48.7±0.2℃and the thermometry needle R1temperature was74.1±0.8℃when themicrowave ablation at300seconds.2、In vivo experimental results(security study):Preoperative and postoperative indicators of liver function ALT、AST and indicators ofrenal function BUN、Cre，there was no difference between groups by statisticalanalysis(P>0.05).3、 In vivo experimental results(effectiveness study)：Experimentalgroup1no injury after the ablation, Histopathological injury grading was1; The experimental group2and control group showed varying degrees of thermal injury,experimental group2,1、2grade of injury were three cases each,3grade of injury weretwo cases; Control group of microwave ablation of liver coagulation necrosis areaadjacent to the stomach wall, the most serious injury,2grade of injury was one case,3、4、5grade of injury were two cases each,6grade of injury was one cases. Degree ofinjury between the groups were significantly different (P=0.000). The Ds of theexperimental group1and experimental group2had no significant difference (P=0.70),but experimental group1to light injury than the experimental group2(P=0.03). Ds ofthe experimental group2and control group had no significant difference (P=0.08), butthe experimental group2to light injury than the control group (P=0.01).Conclusions:1、In vitro study conclusions: An in situ gel of5mm thickness distancefrom the ablation needle was5mm when microwave ablation, could guarantee theorganizational structure adjacent to the ablation zone security.2、The conclusions of thein vivo experiments: It did not impact on liver function and renal function when in situgel used in percutaneous microwave ablation of liver tissue adjacent to the stomach wallof New Zealand white rabbits, Stomach wall injury could be avoided, and it was betterthan the artificial ascites. This technique has a good prospect of application.