Bipolar radiofrequency ablation with 2 × 2 electrodes as a building block for matrix radiofrequency ablation:Ex vivoliver experiments and finite element method modelling

Abstract

Purpose: Size and geometry of the ablation zone obtained by currently available radiofrequency (RF) electrodes is highly variable. Reliability might be improved by matrix radiofrequency ablation (MRFA), in which the whole tumour volume is contained within a cage of x  y parallel electrodes. The aim of this study was to optimise the smallest building block for matrix radiofrequency ablation: a recently developed bipolar 2  2 electrode system. Materials and methods: In ex vivo bovine liver, the parameters of the experimental set-up were changed one by one. In a second step, a finite element method (FEM) modelling of the experiment was performed to better understand the experimental findings. Results:The optimal power to obtain complete ablation in the shortest time was 50-60 W. Performing an ablation until impedance rise was superior to ablation for a fixed duration. Increasing electrode diameter improved completeness of ablation due to lower temperature along the electrodes. A chessboard pattern of electrode polarity was inferior to a row pattern due to an electric field void in between the electrodes. Variability of ablation size was limited. The FEM correctly simulated and explained the findings in ex vivo liver. Conclusions: These experiments and FEM modelling allowed a better insight in the factors influencing the ablation zone in a bipolar 2  2 electrode RF system. With optimal parameters, complete ablation was obtained quickly and with limited variability. This knowledge will be useful to build a larger system with x  y electrodes for MRFA.

Radiofrequency ablation combined with percutaneous ethanol injection for hepatocellular carcinoma: a systematic review and meta-analysis

“…Not surprisingly, non-surgical methods have become a hot topic and are expected to replace surgery. RFA produces its effect through thermal injury generated by electromagnetic energy delivered to the target tissues [33,34]. PEI kills tumours through dehydration and protein denaturation caused by ethanol diffusion into the tumour cells [7].…”

Stereotactic Image-Guidance for Ablation of Malignant Liver Tumors

“…Current evidence shows that the LTP rate is higher in tumors larger than 3 cm and therefore such tumors are not recommended to treat with ablation [30,33]. There are studies reporting larger ablation zones when using multiple needles in parallel, which could cover tumors larger than 3 cm [34]. With stereotactic image-guidance, such treatments can be delivered more reproducibly [6].…”

Caracterização Das Variáveis Físicas E Elétricas Para Protótipo Eletromédico Focado No Tratamento De Tumores Hepaticos Usando Ablação Por Radiofrequência

“…A comparação do desempenho entre eletrodos bipolares acoplados magneticamente e eletrodos convencionais de ablação monopolar e bipolar de RF, foi feito em [6]. Simulações computacionais com experimentos ex-vivo e a modelagem pelo método de elementos finitos pode ser visto em [7]. Experimentos in-vivo e simulações computacionais foram feitas para analisar o efeito da dissipação de calor pelo fluxo sanguíneo dentro de grandes vasos [8].…”