RF-ablation pattern shaping employing switching channels of dual bipolar needle electrodes: ex vivo results

Purpose: Radiofrequency (RF) ablation with mono- or bipolar electrodes is a common procedure for hepatocellular carcinoma (HCC) with a low rate of recurrence for small size tumors. For larger lesions and/or non-round/ellipsoid shapes RF ablation has some limitations and generally does not achieve comparable success rates to microwave ablation or high-intensity focused ultrasound therapies. Materials and methods: To shape RF ablations for matching a tumor size and geometry, we have developed an electronic channel switch box for two bipolar needles that generates multiple selectable ablation patterns. The setup can be used with commercially available mono- or bipolar RF generators. The switch box provides ten selectable ablation procedures to generate different ablation patterns without a relocation of a needle. Five patterns were exemplary generated in ex vivo tissue of porcine liver and chicken breast and visually characterized. Results: Different ablation patterns, e.g., in a L- or U-shape, were achieved. In chicken breast a maximum ablation with a diameter of 4.3cm was obtained and in porcine liver 2.8cm with electrodes of 0.9cm length. Conclusion: The resulting ablations with the electronic switch box and two bipolar needles show the potential ability to manage RF therapies of complex and large tumor geometries. Next steps would be to validate the actual tissue ablation volumes in further ex vivo and preclinical studies and against simulation results.