Experimental Study On Microwave Ablation Of Ex Vivo Bovine Liver And The Effect Of Ionic Solution On Ablation

Part 1 Experimental study on microwave ablation of ex vivo bovine liverObjective:To compare the difference between the 3.0T MRI T₁WI measurement and the actual incision measurement of the microwave ablation area of the ex vivo bovine liver,and to observe and measure the changes of effective ablation range and related parameters of the ex vivo bovine liver under different microwave power and ablation time.Methods: 1.Ablation zone section observation The microwave ablation antenna and the temperature measuring needle were inserted along the long axis of the ex vivo bovine liver.The microwave power was set to 80 w.When the temperature measuring needle reached 60?,the ablation was immediately completed.After the ablation,the general cross-sectional view was observed.According to the identification of the ablation zone at 60?,The complete ablation zone was identified and repeated 5 times.2.Study on parameters related to microwave ablation Constant ablation time is 480 s,adjusting microwave power?20w,40 w,60w,80 w,100w?and constant microwave power is 80 w,adjusting ablation time?120s,240 s,360s,600 s,900s,1800s?,and the ex vivo bovine liver was randomly divided into 12 groups for microwave ablation,and each group was repeated 5 times.Immediately after ablation,the 3.0T MRI T₁WI was used to measure the long-axis diameter and short-axis diameter of the ablation zone and compared with the incision measurement.The ablation zone volume,applied energy,ratio of ablation zone volume to applied energy and sphericity index of each ablation zone were calculated by microwave power,ablation time,long-axis diameter and short-axis diameter of the ablation zone.Results: 1.Ablation zone section observation Microwave ablation produced three discrete viability zones.The first zone is a carbonized zone,which is black or dark brown,the second zone is a complete ablation zone,which is grayish white,and the third zone is an incomplete ablation zone,which is pink.According to the positioning of the temperature measuring needle,the first zone and thesecond zone are defined as effective ablation zone.2.Study on parameters related to microwave ablation The 3.0T MRI T₁WI measurement and the actual incision were used to measure the long-axis diameter and short-axis diameter of the zone,and the ablation zone volume,the applied energy,the ratio of ablation zone volume to applied energy and the sphericity index of the ablation zone were calculated,and a total of 416 data were obtained.According to the Bland-Altman analysis,the long-axis diameter of the microwave ablation zone measured by T₁WI has a good agreement with the actual long-axis diameter of the microwave ablation zone 95.0%?57/60?.The short-axis diameter of the microwave ablation zone measured by T₁WI has a good agreement with the actual short-axis diameter of the microwave ablation zone 96.7%?58/60?.The ablation volume?ml?is linearly related to the output energy?k J?.The regression equations are: actual incision measured volume = 0.083 × output energy + 3.996;MRI measured ablation volume = 0.665 × output energy + 2.571.At the same microwave applied energy?20w×480s and 80w×120s,40w×480s and 80w×240s,60w×480s and 80w×360s,100w×480s and 80w×600s?,the longer the ablation time,the closer the sphericity index of the ablation zone is to 1.Conclusions: 1.Ablation zone section observation Microwave ablation is divided into three zones,namely carbonization zone,complete ablation zone and incomplete ablation zone.The carbonized zone and the complete ablation zone are effective ablation zones.2.Study on parameters related to microwave ablation In the ex vivo bovine liver experiment,3.0T MRI T₁WI was used to immediately after ablation to effectively evaluate the length-axis diameter and the short-axis diameter of the microwave ablation zones.The applied energy is linearly related to the ablation zone volume.At the same microwave applied energy,the longer the ablation time,the more round the ablation zone.Part 2 Experimental study on the effect of ionic solution on microwave ablationObjective:To investigate the effects of different types and concentrations of ionic solutions on the temperature and extent of microwave ablation.To observe the change of the agarose gel model to reach 60 ° C by adjusting the ion concentration,microwave power,and ablation distance,and to observe and measure the effect of CT-guided local injection of hypertonic sodium iodide solution on the area of microwave ablation in an ex vivo bovine liver model.Methods: 1.Microwave ablation experiment of different types and concentrations of ionic solution in agarose model.Prepare some agarose gel model,place 0.2ml of different solutions in the microtube to simulate local injection and insert the temperature measuring needle into the microtube.13 groups of experiments were carried out according to the type of ion solution around the temperature measuring needle?sodium iodide,sodium chloride?,substance concentration?0mg/ml,40mg/ml,100mg/ml,259mg/ml?,the distance between the microwave ablation antenna and the temperature measuring needle?1.0cm,1.5cm,2.0cm?,microwave power?60w,80w?.Measure the time to reach 60?(T₆₀),and each group was repeated 5 times.2.Experimental study on the effect of CT-guided local injection of hypertonic sodium iodide solution on the area of microwave ablation in an ex vivo bovine liver model Prepare and measure the CT values of distilled water?0 mg/ml sodium chloride solution?,100 mg/ml sodium chloride solution,100 mg/ml and 259 mg/ml sodium iodide solution.Prepare 25 pieces of ex vivo bovine liver in a suitable shape.Establish experimental group and control group.The microwave power was set to 80 w and the ablation time was set to 640 s.The experimental group was subjected to microwave ablation after injecting 1 ml of distilled water or 259 mg/ml of sodium iodide solution at 1.5 and 2.0 cm from the microwave ablation antenna under CT guidance.A total of 4 groups were measured.The control group was directly subjected to microwave ablation.Each group was scanned by MRI T₁WI immediately after microwave ablation and repeated 5 times.Results: 1.Microwave ablation experiment of different types and concentrations of ionic solution in agarose model A total of 65 data were obtained.Substance concentration: at the same ablation distance?1.0cm,1.5cm,2.0cm?and microwave power?60w,80w?,with the increase of the concentration of sodium chloride solution?100mg/ml,40mg/ml,0mg/ml?,T₆₀ is obviously shortened.?P<0.05?.Different solutes: when the microwave power was 80 w and the microwave ablation antenna was 1.0cm,There was no significant difference in T₆₀?65.2±11.7s,64.2±8.1s,P=0.879?between 100 mg/ml sodium chloride solution and 259 mg/ml sodium iodide solution.And there was no significant difference in T₆₀?117.6±16.1s,112.4±13.8s,P=0.599?between 40 mg/ml sodium chloride solution and 100 mg/ml sodium iodide solution.Microwave power: at the same ablation distance?1.0cm,1.5cm,2.0cm?and sodium chloride concentration?0mg/ml,40mg/ml,100mg/ml?,the T₆₀ with microwave power of 80 w were significantly less than those with microwave power of 60w?P<0.05?.Ablation distance: at the same concentration of sodium chloride solution?40mg/ml,100mg/ml?and microwave power?60w,80w?,with the increase of ablation distance?1.0cm,1.5cm,2.0cm?,T₆₀ was significantly prolonged?P<0.05?.2.Experimental study on the effect of CT-guided local injection of hypertonic sodium iodide solution on the area of microwave ablation in an ex vivo bovine liver model The CT value of the 259 mg/ml sodium iodide solution was 2989 HU,and the CT value of the 100 mg/ml sodium iodide solution was 1369 HU.When the injection point is at the same distance from the microwave ablation antenna?1.5cm or 2.0cm?,the short-axis diameter of the ablation zone injected with 259 mg/ml sodium iodide was significantly larger than that of the distilled water and the non-injection blank control group.Conclusions: 1.Microwave ablation experiment of different types and concentrations of ionic solution in agarose model Injection of ionic solution helps achieve an effective microwave ablation temperature faster,and the temperature is positively correlated with ion concentration and microwave power,and negatively correlated with ablation distance.2.Experimental study on the effect of CT-guided local injection of hypertonic sodium iodide solution on the area of microwave ablation in an ex vivo bovine liver model Local injection of high concentration sodium iodide solution under CT guidance can increase the microwave ablation area in an ex vivo bovine liver model.In addition,since the concentration of sodium iodide solution is positively correlated with its CT value,CT can also monitor whether sodium iodide is effectively concentrated and measure the concentration area.