Experimental Study Of Single-fiber Laser Ablation In Ex Vivo Porcine Liver

Objectives1.To observe the relationship between the morphology,volume and extent of the ablation foci formed by the Nd-YAG(neodymium:yttrium-aluminum-garnet)laser fiber when ablating fresh isolated pig liver at a limited maximum energy(1800 J)and the fiber emission power,ablation time,the length of the fiber beyond the puncture needle and the added medium(physiological saline),and to analyze and compare the ablation indexes with time,power,length of the needle and whether The dynamic changes of physiology were analyzed.2.To find the law of temperature change next to the ablation foci before and after adding physiological saline,so as to guide the clinic and provide reference indicators for clinical work.Materials and methodsThe Nd-YAG(neodymium:yttrium-aluminum-garnet)laser fiber was inserted into the pig liver for ablation test,avoiding the bile ducts and large blood vessels of the pig liver,selecting thicker liver lobes(thickness>4cm)for the test,and fixing the fiber implantation depth of 4cm.The laser ablation power and time in group A were 4W4W(1min、2 min、3min、4min、5 min)、5W(1min、2 min、3min、4min、5min)、6W(1min、2 min、3min、4min、5min),and the laser ablation power and time in group B were4W(1 min、2 min、3min、4min、5 min)、5W(1min、2 min、3min、4min、5min)、6W(1min、2 min、3min、4min、5min),thus forming a total of 24 test units according to different time,power,and needle length,and each unit was tested 10 times(the first five times without adding saline,and the last five times with adding saline),for a total of 240 tests.After the experiments,the morphology of the ablation range was observed with the naked eye;the pathological and imaging changes of each ablation area were observed after CT scan and H-E staining;the transverse and longitudinal diameters of the ablated necrotic and carbonized range were measured and the volume of the ablation range was calculated,and the changes of all the ablation data with time,power and needle length,and whether saline was added or not were analyzed,and the changes of temperature next to the ablation range before and after the addition of saline were found.The pattern of change of temperature next to the ablation range before and after the addition of saline was also investigated.Results1.Under the naked eye:all ablated necrotic coagulation morphology was similar to ellipsoidal shape,and clearly demarcated from the surrounding normal liver tissues.2.The CT value of the ablation center was the lowest,and the CT value gradually increased at 0.5cm,1 cm and 1.5 cm away from the ablation center until it was similar to the CT value of the surrounding normal liver tissue.The closer the ablation center was to the ablation center,the more complete the cell necrosis was,and the more different the morphology was from the normal liver tissue.3.The morphology of the coagulated necrotic range formed by single fiber laser ablation was related to the set ablation power,time and needle length,and whether saline was added or not,while for the carbonized area,its longitudinal diameter was related to the ablation power,time and needle length,and whether saline was added or not,but its transverse diameter was only related to whether saline was added or not.The longer the ablation time,the larger the volume(V),transverse diameter(TD)and longitudinal diameter(LD)of the ablated range,while only the longitudinal diameter of the carbonized zone increased with the increase of ablation time(P<0.001),and the transverse diameter remained unchanged(P>0.05).The higher the ablation power,the larger the volume(V),transverse diameter(TD)and longitudinal diameter(LD)of the ablation range,and the carbonized area only increased in longitudinal diameter with the increase of ablation power(P<0.001),while the transverse diameter remained unchanged(P>0.05).After the addition of saline,the ablation range and carbonization range decreased(P<0.001).Comparing the data of the two groups with the needle length of 3 mm and 5 mm,it was found that the volume,transverse diameter,longitudinal diameter of the ablation foci and the longitudinal diameter of the carbonization range were larger in the 5 mm group(P<0.05),while the transverse diameter of the carbonization range remained unchanged(P>0.05).4.After fixing the ablation power,time,and needle length with saline,the temperature at 5mm and 10mm from the ablation center decreased(P<0.001).Conclusion1.When the ablation power of the fixed ablation fiber,the longer the time of ablation,the larger the transverse diameter,the longitudinal diameter,the volume of the obtained coagulation foci and the longitudinal diameter of the carbonized area.The cross-sectional and longitudinal diameters of the coagulation range,the volume of the obtained coagulation range and the longitudinal diameter of the carbonized zone increased in the 5-mm needle length group compared to the 3-mm group,and the cross-sectional diameter decreased with the addition of saline.In this experiment,we found that the transverse diameter of the carbonation zone was only related to whether saline was added or not.2.After the addition of saline,the temperature around the ablation zone decreased.