No-touch radiofrequency ablation using multiple electrodes: An in vivo comparison study of switching monopolar versus switching bipolar modes in porcine livers

Abstract

ObjectiveTo evaluate the in vivo technical feasibility, efficiency, and safety of switching bipolar (SB) and switching monopolar (SM) radiofrequency ablation (RFA) as a no-touch ablation technique in the porcine liver.Materials and methodsThe animal care and use committee approved this animal study and 16 pigs were used in two independent experiments. In the first experiment, RFA was performed on 2-cm tumor mimickers in the liver using a no-touch technique in the SM mode (2 groups, SM1: 10 minutes, n = 10; SM2: 15 minutes, n = 10) and SB-mode (1 group, SB: 10 minutes, n = 10). The technical success with sufficient safety margins, creation of confluent necrosis, ablation size, and distance between the electrode and ablation zone margin (DEM), were compared between groups. In the second experiment, thermal injury to the adjacent anatomic organs was compared between SM-RFA (15 minutes, n = 13) and SB-RFA modes (10 minutes, n = 13).ResultsThe rates of the technical success and the creation of confluent necrosis were higher in the SB group than in the SM1 groups (100% vs. 60% and 90% vs. 40%, both p < 0.05). The ablation volume in the SM2 group was significantly larger than that in the SB group (59.2±18.7 cm3 vs. 39.8±9.7 cm3, p < 0.05), and the DEM in the SM2 group was also larger than that in the SB group (1.39±0.21 cm vs. 1.07±0.10 cm, p < 0.05). In the second experiment, the incidence of thermal injury to the adjacent organs and tissues in the SB group (23.1%, 3/13) was significantly lower than that in the SM group (69.2%, 8/13) (p = 0.021).ConclusionSB-RFA was more advantageous for a no-touch technique for liver tumors, showing the potential of a better safety profile than SM-RFA.

Recent Advances in the Image-Guided Tumor Ablation of Liver Malignancies: Radiofrequency Ablation with Multiple Electrodes, Real-Time Multimodality Fusion Imaging, and New Energy Sources

“…Recently, Chang et al ( 24 55 ) assessed the feasibility and optimal protocol of the “no-touch” ablation technique and evaluated both the switching monopolar mode as well as switching bipolar mode for “no-touch” ablation. In an ex vivo study that used a bovine liver, both switching monopolar and switching bipolar modes were demonstrated to be feasible for “no-touch” ablation.…”

“…In addition, the distance between the electrode and ablation zone margin of the switching bipolar mode was significantly smaller than that of the switching monopolar mode (1.39 cm vs. 1.86 cm, p < 0.001) as RF energy can be more focused between two electrodes ( 55 ). Chang et al ( 24 ) also assessed the incidence of adjacent organ injury during the “no-touch” ablation technique in their in vivo study using a porcine liver. They found that the frequency of adjacent organ injury after switching bipolar mode “no-touch” RFA was significantly lower than that after switching monopolar mode “no-touch” RFA (23.1% vs. 69.2%, p = 0.021).…”

“…There have been several efforts to improve the clinical effectiveness of the RFA procedure for the management of patients with malignant hepatic tumors by either improving the efficiency of the RF system in the creation of an ablation zone or using a more precise guiding system ( 21 22 ). More recently, RFA with multiple electrodes for switching between monopolar or bipolar/multipolar modes by using a multi-channel generator or switching controller systems have been used in clinical practice, and they demonstrated that larger ablation volumes were created in a given amount of time compared to the RFA with a single electrode ( 23 24 25 26 ). In addition, the real-time US/CT and magnetic resonance (MR) image fusion technique have also demonstrated their value for expanding the feasibility of RFA and improving the therapeutic efficacy of RFA in local tumor control of HCC or CRLM ( 18 21 ).…”

Influence of interapplicator distance on multibipolar radiofrequency ablation during physiological and interrupted liver perfusion in an in vivo porcine model

“…Recently, mbRFA has further been extended to no-touch mbRFA, where direct contact with malignant tissue is avoided by placing multiple electrodes around the tumour. Studies showed that no-touch mbRFA reduces the risk of needle track seeding and moreover, is able to assure an adequate peritumoral safety margin 9 – 11 . As larger ablation areas are achieved, no-touch mbRFA is also becoming a promising option for the curative treatment of HCC > 5 cm 12 – 14 .…”

Thermal and thermal damage responses during switching bipolar radiofrequency ablation employing bipolar needles: A computational study on the effects of different electrode configuration, input voltage and ablation duration

“…There has been a surge in popularity in the use of bipolar radiofrequency ablation (bRFA) for treating liver cancer, as evident by the number of research studies that have been published over the past 5 years 1‐6 . Bipolar radiofrequency ablation differs from monopolar RFA (mRFA), in that the technique does not make use of grounding pads in order to complete the electrical circuit.…”