Design of a Novel Electrode of Radiofrequency Ablation for Large Tumors: A Finite Element Study

2017 ◽  
Author(s):  
Zheng Fang ◽  
Bing Zhang ◽  
Michael Moser ◽  
Edwin Zhang ◽  
Wenjun Zhang
Keyword(s):  
Finite Element ◽  
Radiofrequency Ablation ◽  
Liver Tumor ◽  
Liver Tumors ◽  
Ablation Volume ◽  
Round Shape ◽  
Complete Ablation ◽  
Sphericity Index ◽  
Tissue Interface ◽  
Temperature Controlled

Objective: The aim of this study was to design a novel radiofrequency (RF) electrode for larger and more round ablation volumes and its ability to achieve the complete ablation of liver tumors (> 3 cm in diameter) using finite element method. Methods: A new RF expandable electrode comprising three parts (i.e., insulated shaft, changing shaft, and hooks) was designed. Two modes of this new electrode (i.e., monopolar expandable electrode (MEE) and hybrid expandable electrode (HEE)) and a commercial expandable electrode (CEE) were investigated using liver tissue with and without liver tumor. A temperature-controlled radiofrequency ablation (RFA) protocol with a target temperature of 95 °C and an ablation time of 15 minutes was used in this study. Both the volume and shape of the ablation zone were studied for all RF electrodes. A large liver tumor with the diameter of 3.5 cm was used to evaluate the effectiveness on the complete ablation of the new designed electrode. Results: In the first scenario (without liver tumor), the ablation volumes of CEE, HEE, and MEE were 9.96 cm3, 41.0 cm3, and 46.14 cm3, respectively. The values of sphericity index (SI) of CEE, HEE, and MEE were 0.36, 0.94, and 0.98, respectively. The best performance was achieved by the MEE electrode. In the second scenario (with liver tumor), the ablation volumes of MEE and CEE were 67.56 cm3 and 20.62 cm3, respectively. Also, a rounder ablation volume was generated by MEE compared to CEE (SI: 0.98 vs 0.55). Conclusion: This study concludes that compared with CEE, both MEE and HEE are able to get larger and more round ablation volumes due to the larger electrode-tissue interface and more round shape of hooks; compared with HEE, MEE is better to get a larger and rounder ablation volume; MEE is able to ablate a large liver tumor (i.e., 3.5 cm in diameter) completely.

scholarly journals Design of a Novel Electrode of Radiofrequency Ablation for Large Tumors: A Finite Element Study

2017 ◽  
Vol 1 (1) ◽  
Author(s):  
Zheng Fang ◽  
Bing Zhang ◽  
Michael Moser ◽  
Edwin Zhang ◽  
Wenjun Zhang
Keyword(s):  
Finite Element ◽  
Radiofrequency Ablation ◽  
Liver Tumor ◽  
Liver Tumors ◽  
Safety Margin ◽  
Ablation Volume ◽  
Sphericity Index ◽  
Tissue Interface ◽  
Temperature Controlled ◽  
Complete Tumor

The aim of the study was to design a novel radiofrequency (RF) electrode for larger and rounder ablation volumes and its ability to achieve the complete ablation of liver tumors larger than 3 cm in diameter using finite element method. A new RF expandable electrode comprising three parts (i.e., insulated shaft, changing shaft, and hooks) was designed. Two modes of this new electrode, such as monopolar expandable electrode (MEE) and hybrid expandable electrode (HEE), and a commercial expandable electrode (CEE) were investigated using liver tissue with (scenario I) and without (scenario II) a liver tumor. A temperature-controlled radiofrequency ablation (RFA) protocol with a target temperature of 95 °C and an ablation time of 15 min was used in the study. Both the volume and shape of the ablation zone were examined for all RF electrodes in scenario I. Then, the RF electrode with the best performance in scenario I and CEE were used to ablate a large liver tumor with the diameter of 3.5 cm (scenario II) to evaluate the effectiveness of complete tumor ablation of the designed RF electrode. In scenario I, the ablation volumes of CEE, HEE, and MEE were 12.11 cm3, 33.29 cm3, and 48.75 cm3, respectively. The values of sphericity index (SI) of CEE, HEE, and MEE were 0.457, 0.957, and 0.976, respectively. The best performance was achieved by using MEE. In scenario II, the ablation volumes of MEE and CEE were 71.59 cm3 and 19.53 cm3, respectively. Also, a rounder ablation volume was achieved by using MEE compared to CEE (SI: 0.978 versus 0.596). The study concluded that: (1) compared with CEE, both MEE and HEE get larger and rounder ablation volumes due to the larger electrode–tissue interface and rounder shape of hook deployment; (2) MEE has the best performance in getting a larger and rounder ablation volume; and (3) computer simulation result shows that MEE is also able to ablate a large liver tumor (i.e., 3.5 cm in diameter) completely, which has at least 0.785 cm safety margin.

Liver tumor laser ablation – increase in the subacute ablation lesion volume detected with post procedural MRI

2010 ◽  
Vol 51 (5) ◽  
pp. 505-511 ◽  
Author(s):  
Roberto Blanco Sequeiros ◽  
Juho Kariniemi ◽  
Risto Ojala ◽  
Li Chengli ◽  
Marianne Haapea ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Liver Tumor ◽  
Liver Tumors ◽  
Image Data ◽  
Initial Therapy ◽  
Tissue Response ◽  
Lesion Volume ◽  
Ablation Zone ◽  
Ablation Volume ◽  
Contrast Enhanced

Background: The use of image-guided thermoablative methods in liver tumor treatment has expanded rapidly due to encouraging results and advanced imaging. However, little is known about the treatment-induced tissue response and effects on imaging findings during the subacute post procedural period. Purpose: To study the development of subacute ablation zone volume with magnetic resonance imaging (MRI) after laser-mediated liver tumor thermal therapy. Material and Methods: In all, 16 laser ablations were performed on 16 liver tumors resulting in 16 ablation zones in 11 consecutive patients. A low-field 0.23 T C-arm MRI scanner was used for imaging and procedural guidance. Repeated dynamic contrast-enhanced T1, contrast-enhanced T1 FSE, and T2 FSE studies of liver were performed at 0 and 72 h after the procedure. Ablation zone volumes were registered from the acquired image data. Results: MRI scans showed a significant increase of ablation volume in all imaging sequences obtained at 72 h after the initial therapy. Conclusion: After laser ablation, there is a progressive perfusion decrease in the ablation site leading to an increase in the ablation volume. Post procedural baseline MRI at 72 h from the treatment provides more precise information about the ablation result than can be obtained with immediate post procedural MRI.

scholarly journals Parametric evaluation of impedance curve in radiofrequency ablation: A quantitative description of the asymmetry and dynamic variation of impedance in bovine ex vivo model

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245145
Author(s):  
Ronei Delfino da Fonseca ◽  
Paulo Roberto Santos ◽  
Melissa Silva Monteiro ◽  
Luciana Alves Fernandes ◽  
Andreia Henrique Campos ◽  
...  
Keyword(s):  
Radiofrequency Ablation ◽  
Liver Tumors ◽  
Ex Vivo ◽  
Early Stage ◽  
Quantitative Description ◽  
Maximum Point ◽  
Performance Indices ◽  
Ex Vivo Model ◽  
Ablation Volume ◽  
Impedance Curve

Radiofrequency ablation (RFA) is a treatment for liver tumors with advantages over the traditional treatment of surgical resection. This procedure has the shortest recovery time in early stage tumors. The objective of this study is to parameterize the impedance curve of the RFA procedure in an ex vivo model by defining seven parameters (t1/2, tminimum, tend, Zinitial, Z1/2, Zminimum and Zend). Based on these parameters, three performance indices are defined: one to identify the magnitude of impedance curve asymmetry (δ), one Drop ratio (DR) describing the percentage of impedance decrease until the minimum impedance point is reached, and Ascent Ratio (AR) describing the magnitude of increase in impedance from the minimum impedance point to its maximum point. Fifty ablations were performed in a bovine ex vivo model to measure and evaluate the proposed parameters and performance index. The results show that the groups had an average δ of 29.02%, DR of 22.41%, and AR of 545.33% for RFA without the use of saline or deionized solutions. The saline solution and deionized water-cooled groups indicated the correlation of performance indices δ, DR, and AR with the obtained final ablation volume. Therefore, by controlling these parameters and indices, lower recurrence is achieved.

Design of a Novel Electrode of Radiofrequency Ablation for Large Tumors: In Vitro Validation and Evaluation

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Zheng Fang ◽  
Micheal A. J. Moser ◽  
Edwin Zhang ◽  
Wenjun Zhang ◽  
Bing Zhang
Keyword(s):  
Computer Simulation ◽  
Radiofrequency Ablation ◽  
Liver Tumor ◽  
Tumor Model ◽  
Egg White ◽  
Large Tumor ◽  
Ablation Volume ◽  
Conventional Electrode

In a prior study, we proposed a novel monopolar expandable electrode (MEE) for use in radiofrequency ablation (RFA). The purpose of our work was to now validate and evaluate this electrode using on in vitro experimental model and computer simulation. Two commercially available RF electrodes (conventional electrode (CE) and umbrella electrode (UE)) were used to compare the ablation results with the novel MEE using an in vitro egg white model and in vivo liver tumor model to verify the efficacy of MEE in the large tumor ablation, respectively. The sharp increase in impedance during RFA procedures was taken as the termination of RFA protocols. In the in vitro egg white experiment, the ablation volume of MEE, CE, and UE was 75.3 ± 1.6 cm3, 2.7 ± 0.4 cm3, and 12.4±1.8 cm3 (P < 0.001), respectively. Correspondingly, the sphericity was 88.1±0.9%, 12.9±1.3%, and 62.0 ± 3.0% (P < 0.001), respectively. A similar result was obtained in the in vitro egg white computer simulation. In the liver tumor computer simulation, the volume and sphericity of ablation zone generated by MEE, CE, and UE were 36.6 cm3 and 93.6%, 3.82 cm3 and 16.9%, and 13.5 cm3 and 56.7%, respectively. In summary, MEE has the potential to achieve complete ablation in the treatment of large tumors (>3 cm in diameter) compared to CE and UE due to the larger electrode–tissue interface and more round shape of hooks.

Comparison of Ablation Volume Produced With Multi-Tine Dry Type and Wet Type Electrodes During Radio Frequency Ablation: An In Vitro Study

2018 ◽  
Author(s):  
Sundeep Singh ◽  
Ramjee Repaka
Keyword(s):  
Radiofrequency Ablation ◽  
Temperature Distribution ◽  
Radio Frequency ◽  
Soft Tissues ◽  
In Vitro Study ◽  
Vitro Study ◽  
Thermo Electric ◽  
Ablation Volume ◽  
Temperature Controlled

The present in vitro study aims at comparing the ablation volume obtained with commercially available RITA’s StarBurst® XL (dry type) and StarBurst® Xli-e (wet type) multi-tine electrodes during radiofrequency ablation (RFA) procedure. The experiments have been conducted on polyacrylamide based tissue-mimicking phantom gel whose thermo-electric properties are similar to that of the soft tissues. A temperature-controlled RFA has been performed utilizing AngioDynamics RITA 1500X® radiofrequency generator. The maximal longitudinal and maximal transverse dimensions of the coagulated phantom gels have been measured from which the derived ablation volume has been calculated. Further, the temperature distribution and power delivered with the dry type and wet type electrodes have been compared. The in vitro study revealed that the efficacy of wet type electrode is more pronounced as compared to the dry type electrode. Moreover, it has been found that both the electrodes are capable enough of producing ablation volume up to 5 cm in diameter.

The Effect of Perfusion Rate on the Radiofrequency Ablation of Liver Tumors

2013 ◽  
Author(s):  
M. Erol Ulucakli ◽  
Christopher S. Lavery
Keyword(s):  
Finite Element ◽  
Radiofrequency Ablation ◽  
Tumor Tissue ◽  
Liver Tumors ◽  
Coagulation Necrosis ◽  
Medical Procedure ◽  
Perfusion Rate ◽  
Needle Probe ◽  
Radiological Procedures ◽  
Finite Element Methodology

Radiofrequency ablation is a medical procedure used to treat a variety of illnesses including liver carcinomas that cannot be treated by resection or radiological procedures. A multi-physics code was used to solve the Bio-heat Equation by a finite element methodology. The volume of coagulation necrosis caused by the heating of the tumor tissue as a function of perfusion rate was determined. A multi-needle probe deposited the RF energy into the tissue. Once the tissue was heated to greater than 50°C it was considered irreversibly damaged. Increasing perfusion rates reduced the size of the lesion. In order to heat a volume to a required temperature the time elapsed did increase.

Clinical Application of Radiofrequency Ablation for Malignant Liver Tumor during Interruption of Hepatic Blood Flow

2000 ◽  
Vol 18 ◽  
pp. 121-125
Author(s):  
Takashi Shibata ◽  
Takahiro Niinobu ◽  
Masashi Kitada ◽  
Takashi Shimano ◽  
Motohisa Takami ◽  
...  
Keyword(s):  
Blood Flow ◽  
Radiofrequency Ablation ◽  
Clinical Application ◽  
Hepatic Blood Flow ◽  
Liver Tumor ◽  
Malignant Liver Tumor ◽  
Malignant Liver
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