Double radiofrequency ablation is more extensive with a spherical zone shape compared to single ablation in a pig liver model

Objective : We compared the duration of ablation and the area of coagulation necrosis between a single ablation method (SAM) and a double ablation method (DAM) with a ’multitined expandable’ electrode (LeVeen 2cm) for radiofrequency ablation (RFA) using pig liver.
Method : In the SAM group, ablation was completed after the first roll-off. In the DAM group, an additional ablation was performed to achieve a second roll-off. The comparison was made of the time required for roll-off and the extent of coagulation necrosis between the both groups. The Ellipticity index (EI) quantitatively describes the shape of the general RF ablation zone in the axial plane.
Results : There was no statistically significant difference in the interval until the first roll-off between both groups (SAM group : 100.7±24.7 seconds vs DAM group : 103.2±37.7 seconds, P=0.43). In the DAM group, the interval from the start of the additional ablation until the second roll-off was 154.0±86.9 seconds, longer than the interval for the first roll-off (P=0.023). The extent of coagulation necrosis was significantly more extensive in the DAM group (axial diameter, mean±SD, 26.2±2.8 mm)×(maximal diameter : 29.3±1.6 mm)× (minimal diameter : 26.5±3.6 mm) compared to the SAM group with (23.0±3.3 mm)×(23.7± 3.1 mm)×(20.0±2.5 mm), respectively. Although there was no statistically significant difference in the EI between both groups, macroscopically, the shape of coagulation necrosis tended to be non-spherical in the SAM group and spherical in the DAM group. Conclusions : The DAM with a ’multitined expandable’ electrode was more extensive with a spherical zone shape compared to the SAM.