Using a tubular electrode for radiofrequency ablation

Abstract

Purpose -Due to its good mechanical and biocompatibility characteristics, nitinol SEMS is a popular endoprothesis used for relieving stricture problems in hollow organs due to carcinomas. Besides its mechanical application, SEMS can be regarded as well as potential electrode for performing RF ablation therapy on the tumor. The purpose of this work is to perform numerical and experimental analyses in order to characterize the lesion volume induced in biological tissue using this kind of tubular electrode. Design/methodology/approach -Data concerning electrical conductivity and dimension of the damaged tissue after RF ablation procedure were obtained from ex vivo samples. Next, numerical models using 3D finite element method were obtained reassembling the conditions considered at experimentation setup and results were compared. Findings -Numerical and experimental results show that a regular volume of damaged tissue can be obtained considering this type of electrode. Also, results obtained from numerical simulation are close to those obtained by experimentation. Originality/value -SEMSs, commonly used as devices to minimize obstruction problems due to the growth of tumors, may still be considered as an active electrode for RF ablation procedures. A method considering this observation is presented in this paper. Also, numerical simulation can be regarded in this case as a tool for determining the lesion volume.

Saline‐enhanced RF ablation on a cholangiocarcinoma: a numerical simulation

“…The material properties required for solving the models considered in this work were obtained from the literature Antunes et al (2010c), Tziafalia et al (2006), Haemmerich et al (2001) and Haemmerich et al (2003b) and are summarized in Tables I and II. For the electrical conductivity of the outer sections of the tumor it was considered a value of 0.269 S/m Haemmerich et al (2003b).…”

“…As nitinol stents can be used to reduce stricture problems of the bile duct, these can be also considered as potential electrodes for hyperthermia treatments. Previous works Antunes et al (2010a), Antunes et al (2010b) and Antunes et al (2010c) show that nitinol stents can be considered as a feasible solution for delivering radiofrequency (RF) energy in a tumor located in a hollow organ. However, the tissue lesion induced using this kind of electrode is not completely uniform due to the convective heat transfer associated to the blood perfusion in the portal vein and hepatic artery.…”

An Experimental and Numerical Investigation of Phase Change Electrodes for Therapeutic Irreversible Electroporation

“…The edge-to-edge spacing was held constant for all electrode radii to ensure equal voltage-to-distance ratios (2000 V/cm). The pulse duration and the total time of pulsing were reduced to 90/is and 70s, respectively, and the electrical conductivity of the ultrasound gel was maintained at 0.13S/m, which matches that of liver tissue at 25 °C [36]. Following the initial parametric study, simulations on reduced electrode spacings (1.5, 1.0, and 0.5 cm) more comparable to the experimental setup were also performed to test the limit of PCM effectiveness and evaluate changes in the spatial temperature distribution.…”

Modelling of a bipolar stent-based electrode for thermal radio frequency ablation of tumours located in hollow organs

“…The end segments and the middle segment correspond to the grounded elements, while the remaining segments correspond to the active elements (Figure 3(c)). The material properties for solving the proposed models are summarised in Tables I and II and were obtained from literature (Antunes et al, 2012c;Tziafalia et al, 2006;Haemmerich et al, 2001. Both electrical conductivities for healthy, σ l (T), and tumorous tissue, σ t (T), were considered temperature-dependent, increasing 2 per cent (Antunes et al, 2012c), and, for the tumorous tissue, it was assumed equal to 0.269 S/m, also at 25°C .…”