Comparative Study Of Three Microwave Antenna With Different Diameters In Vitro Porcine Lungs

PurposeTo investigate the ablation ranges of three microwave antenna with different diameters,such as 14 G,15G,18 G,in vitro porcine lungs,which would establish crucial experimental basis for clinical practice.MethodsIn this study,microwave ablations(MWA)were performed in three types of power output with 50 W,60W,70 W for 3,6,9,and 12 min by three various microwave antennas which outer diameter were 1.3mm(18G),1.8mm(15G),2.0mm(14G).A total of 216 ablations were performed(6 ablations per time setting in the 14 G,15G,and 18 G microwave antennae).The power instrument was tested and adjusted before the experiment.We observed the shape and extent of the coagulation zone,and measured the maximum long-axis(along the needle axis;length [L])and maximum short-axis(perpendicular to the needle;diameter [D])of the ablation zones with a ruler,and the sphericity index(L/D)were subsequently calculated.The sphericity index can be simplified to the long axis/short axis.The value were recorded,and expressed as the mean±SD.ResultsAll the ablation zones were elliptical of different times and at different powers,and the bargain with the surrounding tissue was clear.Single-sample KS test verified that samples were accorded with normal distribution(p>0.05).Comparison of mean in multiple groups was conducted with analysis of variance(ANOVA).Pairwise comparison among groups for homogeneity of variance was done with LSD-test method,missing variance with Dunnett-t method.The results of Levene test for homogeneity of variance showed that the sphericity index of 3min at 60 W,the diameter and sphericity index of 3min at 70 W were missed variance(p=0.002,0.001,0.000).Therefore,the spherical index of 12 min at 70 W for the 18 Gmicrowave antenna were higher than those of the 14 G and 15G(P < 0.05 each).The difference between 15 G and 14 G were not statistically significant with the spherical index of12 min at 70W(P > 0.05).The short-axis diameters and long-axis diameters and sphericity indiced that except for the spherical index of 12 min at 70 W did not differ statistically from the 14 G,15G,and 18 G groups.ConclusionsIn this study,all the ablation zones were elliptical and had a clear boundary within the surrounding tissues.The ablation zone was divided into three different regions according to the color derived from the center to the edge.The middle of ablation zone was an ellipsoid dark brown necrotic solidification zone,and a minority of tissues appeared an arrow-shaped carbonization central zone along the needle path.Then,a congestive reaction zone appeared grossly as a light red circle closely adjacent to the coagulation necrosis.The size of ablation zone created by the three ablation antennas was showed basically stable.Results showed that the short-axis diameters and long-axis diameters and sphericity indices that except for the spherical index of 12 min at 70 W did not differ statistically among 14 G,15G,and 18 G groups.Compared with 14 G and 15 G,18G microwave antenna had a lower sphericity index in12 min at 70 W.Consequently,the ablation range does not decline with the decreasing of the ablation antenna diameter.18 G microwave antenna can decrease the puncture risk and complication rate in clinical applications.The study results would be a valuable reference to the optimal design of ablation planning and related ablation parameters for the precise minimally invasive treatment.