Multiple-electrode radiofrequency ablations using Octopus® electrodes in anin vivoporcine liver model

Abstract

Objectives: The objective of this study was to determine the in vivo efficacy of radiofrequency ablation (RFA) in porcine liver using Octopus j electrodes for creating a large coagulation compared with RFA using clustered electrodes. Methods: A total of 39 coagulations were created using a 200-W generator and clustered electrodes or Octopus electrodes during laparotomy in 19 pigs. Radiofrequency was applied to the livers using four protocols: (1) Group A-1, monopolar mode using a clustered electrode (n511); (2) Group A-2, monopolar mode using an Octopus electrode (n511); (3) Group B-1, consecutive monopolar mode using three, clustered electrodes (n58); and (4) Group B-2, switching monopolar mode using two Octopus electrodes (n59). The energy efficiency, shape, diameters (D) and volume (V) of the coagulation volume were compared in each of the two groups. Results: The mean maximum D and V of the coagulations in Group A-2 (4.7 cm and 33.1 cm 3 , respectively) were significantly larger than those in Group A-1 (4.1 cm and 20.3 cm 3 , respectively) (p,0.05). Furthermore, the mean minimum D, maximum D and V of the coagulations in Group B-2 were significantly larger than those in Group B-1, i.e. 5.3 vs 4.0 cm, 6.6 vs 4.9 cm and 66.9 vs 30.2 cm 3 , respectively (p,0.05). The energy efficiencies were also significantly higher in Groups A-2 and B-2 than in Groups A-1 and B-1 (p,0.05). Conclusion: The Octopus electrodes were more efficient for creating a large ablation zone than clustered electrodes, and the efficacy of RFA with Octopus electrodes can be amplified in the switching monopolar mode.

Comparison of therapeutic efficacy and safety of radiofrequency ablation of hepatocellular carcinomas between internally cooled 15-G and 17-G single electrodes

“…The measured ablation volume was 25.3 cm radiofrequency electrodes and found that the extent of coagulation necrosis increased from 0.7 to 1.8 cm as the electrode diameter increased from 24 G to 12 G. Our results are also in line with recent studies using separable clustered electrodes, in which 15-G electrodes showed a larger ablation zone than 17-G electrodes under the same conditions. 10,18 In the present study, there was no significant difference in ablation time between the 15-G and the 17-G groups (8.7 6 3.5 min vs 8.4 6 2.5 min; p 5 0.793). This implies that a 15-G electrode can make a similar size ablation zone with shorter ablation time than a 17-G electrode.…”

Evaluation of theIn VivoEfficiency and Safety of Hepatic Radiofrequency Ablation Using a 15-G Octopus® in Pig Liver

“…In our study, the mean value of the ablated volume using the single 15-G Octopus® electrode method with a 1-cm inter-electrode distance (group B) was 64.11 cm 3 . According to a previous literature report (15), the mean value of the ablated volume using a single 17-G Octopus® electrode was 33.08 cm 3 under the same conditions. Based on these results, we suggest that a 15-G Octopus® electrode may exhibit better performance than that of a 17-G Octopus® electrode under the same conditions.…”

“…Basically, the Octopus® electrode is composed of three, cooled-tip electrodes with a 2.5-cm active tip similar to that of a clustered electrode (15). However, the Octopus® electrode differs from the conventional clustered electrode regarding the separability of each individual electrode using a special adaptor which connects the three cables to one piece.…”

“…During the RFA procedure, the temperature at the tip of the electrode was automatically and continuously measured within the generator. Based on the previous ex vivo optimization study (15), RF energy was delivered to the electrodes for 24 minutes.…”

“…Recently, Lee et al (15) demonstrated that RFA using 17-gauge Octopus® (17-G Octopus®) electrodes with three, separate, individual electrodes at a 10-mm inter-electrode distance, was able to provide greater efficiency for creating larger coagulation than conventional, monopolar RFA using clustered electrodes at a 5-mm interelectrode distance. However, in their study, the minimum effective diameters of the coagulation necrosis created by the clusted electrode and the Octopus® electrodes, were 2.99 cm and 3.49 cm, respectively.…”