Comparison Of Microwave Thermosphere Ablation And Conventional Microwave Ablation In Ex Vivo Bovine Livers

Objective: To compare the effectiveness of microwave thermosphere ablation(MTA)and traditional microwave ablation(MWA)in ex vivo bovine livers,and to compare the degree of the heat sink effect in them,aimed at providing some reference for clinical practice.Method: The non-vessel model and vessel model were established using fresh bovine livers.In non-vessel model(n=48),the same power-time settings were used in both MTA group and MWA group: 80 W 12 min,90 W 10 min and 100 W 10 min.Long-axis diameter(Dl),short-axis diameter(Ds1,Ds2),roundness index(R)and the time(t)of temperature 10 mm from the needle rising to 60? were measured.In vessel model(n=144),different vessel diameters(3 mm,5 mm,10mm)and flow rates(15 cm/s,20 cm/s,30 cm/s)were setting,and all of the application power-time setting were 90 W 10 min.The maximum radius(Rmax),the total area of ablation zone(Sz),and the area difference(Sdiff)were analyzed,the temperatures(T)adjacent to the vessel were monitored simultaneously.Result: In non-vessel model,with the same power and time settings,the Dl of MTA group were significantly smaller than MWA group(P<0.01),however,there were no significant difference of Ds1 and Ds2 between the two groups(P>0.05).And MTA group created more spherical ablation zones,since the R of MTA group were more close to 1(P<0.01).In MTA group,the time of temperature 10 mm from the needle rising to 60? were slower than MWA group(P<0.01).In vessel model,the Sdiff of MTA group were hardly affected by the vessel diameters and flow rates(P>0.05),and there were also no statistical significance among different flow rates(P>0.05)in MWA group,but the Sdiff of MWA group were significantly affected by the vessel diameters(P< 0.01).And The Sdiff of MTA group were significantly smaller than MWA group when the vessel diameter was 10 mm(P<0.03),while there were no statistical significance between the two groups when the vessel diameter was 3 mm or 5 mm(P>0.05).There was a similar trend of thetemperatures(T)adjacent to the vessel with time in both MTA group and MWA group,and Maximum temperature during the ablation cycle had a declining trend with increasing vessel diameters and flow rates.Further more,the maximum temperature of MTA group was higher than MWA group with the same vessel diameter and flow rate.Conclusion: Compared to MWA,MTA can produce sizable,regular and more spherical ablation lesions with the same power and time,meanwhile,it is less affected by the heat sink effect.