Multiple-electrode radiofrequency ablation of in vivo porcine liver: comparative studies of consecutive monopolar, switching monopolar versus multipolar modes.
OBJECTIVE
To evaluate the in vivo efficiency of 2 multiple-electrode radiofrequency (RF) systems to create confluent areas of coagulation in porcine liver, compared with consecutive overlapping ablation.


METHODS
A total of 18 coagulations were created with 3 RF devices and 3 internally cooled electrodes at laparotomy in 6 female pigs. RF was applied to the porcine livers in a consecutive, monopolar mode (group A), in a switching monopolar mode (group B), or in a multipolar mode (group C). Energy efficiency values for the RF systems, shape and dimensions, and the coefficients of variation of the coagulation zones were compared in the 3 groups.


RESULTS
The duration of the RF ablation procedures in groups A, B, and C were 36 minutes, 18 minutes, and 21.2 +/- 1.9 minutes. The average energy delivered to produce 1 cm(3) coagulation was greater in group A (5.6 +/- 2.3 kJ/cm(3)) than in group B (1.8 +/- 0.5 kJ/cm(3)) or in group C (2.0 +/- 0.8 kJ/cm(3)) (P < 0.05). The mean volumes of the coagulations in groups A, B, and C were 28.8 +/- 13.2 cm(3) in group A, 49.1 +/- 12.3 cm(3) in group B, and 40.6 +/- 16.3 cm(3) in group C, respectively (P = 0.07). Regarding the shape of the coagulations, the coagulations of groups B (isoperimetric ratio; 0.88) and C (0.84) were more spherical than those of group A (0.69) (P < 0.05). In addition, the coefficients of variation of the volumes of the ablation zones in groups A, B, and C were 0.46, 0.25, and 0.40, respectively.


CONCLUSIONS
Multiple-electrode RF systems in switching monopolar and multipolar modes more efficiently created a larger, confluent, spherical-shaped coagulation than conventional consecutive RF ablation.
Lee
Jeong Min
JM
Department of Radiology, Institute of Radiation Medicine, Seoul National University College of Medicine, Seoul, Korea.
Han
Joon Koo
JK
Kim
Hyo Cheol
HC
Kim
Se Hyung
SH
Kim
Kyung Won
KW
Joo
Seung Moon
SM
Choi
Byung Ihn
BI
D000818:Animals; D017115:Catheter Ablation; D005260:Female; D008099:Liver / Q000473:pathology*; D008107:Liver Diseases / Q000628:therapy*; D008113:Liver Neoplasms / Q000628:therapy*; D013552:Swine