ABSTRACT
Objective To compare the effectiveness of microwave thermosphere ablation( M T A ) and traditional microwave ablation( M WA ) in ex v ivo bovine livers ,and to compare the degree of the heat sink effect in them .Methods T he 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 M T A group and MWA group ,w hich were 80 W 12 min ,90 W 10 min and 100 W 10 min ,respectively . Long‐axis diameter ( Dl) , short‐axis diameter( Ds1 ,Ds2) ,roundness index ( R) and the time of temperature rising to 60℃ at place of 10 mm from the needle were measured .In vessel model( n ＝144) ,different vessel diameters( 3 mm ,5 mm ,10 mm) and flow rates ( 15 cm/s ,20 cm/s ,30 cm/s) were setted . The maximum radius( Rmax) ,total area of ablation zone( Sz ) ,and the area difference ( Sdiff ) were analyzed ,the temperatures adjacent to the vessel were monitored simultaneously . Results In non‐vessel model ,with the same power and time settings ,the Dl of M T A group was significantly smaller than MWA group ( P ＜ 0 .01 ) , however , there was no significant difference of Ds1 and Ds2 between the two groups( P ＞0 .05) . And M T A group created more spherical ablation zones ,since the R of M T A group were more close to 1 ( P ＜0 .01) . In M T A group ,the time of temperature rising to 60 ℃ at place of 10 mm from the needle was slower than MWA group ( P ＜0 .01) . In vessel model ,the Sdiff of M T A group were hardly affected by the vessel diameters and flow rates ( P ＞0 .05) ,and there was also no statistical significance among different flow rates( P ＞0 .05 ) in M WA group ,but the Sdiff of M WA group was significantly affected by the vessel diameters( P ＜0 .01) . And the Sdiff of M T A group was significantly smaller than M WA group when the vessel diameter was 10 mm ( P ＜0 .05) ,while there was no statistical significance between the two groups w hen the vessel diameter was 3 mm or 5 mm( P ＞0 .05) . Conclusions Compared to M WA ,M T A 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 .
ABSTRACT
Objective To explore the impact of local lipiodol deposition in liver of miniature pigs on the shape and size of the necrotic area after microwave ablation (MWA).Methods Ten healthy miniature pigs were selected and equally divided into experimental group and control group (each n=5).In experimental group,transcatheter hepatic arterial embolization with lipiodol was done before microwave ablation,while only standard microwave ablation was performed in control group.Immediate post-ablation CT images were obtained.Long-axis diameter (LAD),short-axis diameter (SAD),sphericity index (SI=SAD/LAD) and volume of ablation zone were calculated.The size and shape of the ablated areas were compared between two groups.Results The mean LAD,SAD,SI and volume of ablation zone in experimental group ([4.21 ± 0.52]cm,[2.87±0.38]cm,0.69±0.10,[18.72±6.08]cm3) were larger than those in control group ([3.71±0.42]cm,[2.19±0.42]cm,0.60±0.09,[9.44±2.29] cm3;all P＜0.05).Conclusion Local deposition of lipiodol in liver parenchyma of miniature pigs can help to produce larger and rounder necrosis in the ablation zone.