Radiofrequency Ablation with an Internally Cooled Monopolar Directional Electrode: Ex Vivo and in Vivo Experimental Studies in the Liver

Yu, Mi Hye; Lee, Jae Young; Jun, Su Ryoung; Kim, Kyung Won; Kim, Se Hyung; Han, Joon Koo; Choi, Byung Ihn

doi:10.1148/radiol.2015142269

Cited by 11 publications

(9 citation statements)

References 32 publications

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“…Thirdly, considering the function complexity and calculation speed, the recessed “tail” proximate to MW antenna generated by cooled water was not modeled. In order to achieve this “tail” shape, the oscillation/fluctuation factor (eg, cosine function) or the heart‐shaped curves can be incorporated into the characterization functions of coagulation zone. In future work, FEM models including large vessels may be constructed to derive the growth models of certain characteristic lengths (eg, the distance from the microwave emission point to the large vessels) and the expressions of thermal coagulation zones.…”

Section: Discussionmentioning

confidence: 99%

Characterization of 2450‐MHz microwave thermal coagulation zone based on characteristic length growth model and shape variation factor

Gao

Wang

et al. 2019

Int J RF Microw Comput Aided Eng

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It is critical for microwave ablation (MWA) treatment planning to evaluate the changes of thermal coagulation zones. In MWA procedures, the shapes and sizes of thermal coagulation zones are gradually evolving over time. To this end, a novel characterization and mapping method of thermal coagulation zones is presented in this article. Firstly, finite element method (FEM) models of temperature distributions for 40, 45, 50, 55, and 60 W microwave ablations were built to derive thermal ablation data of ex vivo porcine livers and were compared with experimental results. Secondly, growth models of characteristic lengths were fitted. Finally, characterization functions of thermal coagulation zones were developed using these growth models. In addition, shape variation factors were incorporated to handle the minor shape variations of thermal coagulation zones. Experimental results showed that these characterization functions could accurately represent the changes of thermal coagulation zones. The standard deviations between prediction results and simulated values were less than 1 mm. The comparative results were statistically analyzed by paired t test (P > 0.05), indicating no significant differences. The proposed method can simply and effectively predict the changes of MWA coagulation zones with time, thus providing reliable coagulation dimensions for the thermal ablation therapies. K E Y W O R D S2-D mapping, coagulation zone, growth model, microwave ablation, shape variation factor 1 | INTRODUCTION MWA has become a widely accepted minimally-invasive procedure for the treatment of liver tumors, 1 with benefits of faster heating rates, larger coagulation zones, and shorter treatment time. 2 All tumor cells are destroyed by high-frequency electromagnetic waves emitted from a thin microwave (MW) antenna. Common clinical MWA devices include 915-and 2450-MHz applicators. However, the efficacy of MWA treatment is still left to the experiences of clinicians and the applications of medical imaging techniques. 3 Open problems delaying MWA clinical applications are mainly linked to the inability to accurately predict and control the growing coagulation zone. 4 For most ablative techniques such as MWA and RFA, thermal-induced tumor coagulation necrosis will occur instantly at temperatures of 55 C or higher. 5,6 In the treatment of liver tumors, the temperature of 54 C is often selected as the thermal coagulation threshold. 7,8 Therefore, in this work, we focus on accurately characterizing the shapes and sizes of 54 C isothermal surface (IS-54) to ensure the success of the treatment of liver tumors.MWA treatment planning is important for liver tumor thermal ablations. The optimized treatment schemes require "conformal" coverage of the tumors, with a safety margin of 5 to 10 mm, and minimized damages of surrounding normal tissues. 9 In the current MWA treatment planning, the estimation of thermal coagulation zones is questionable, because only some simplified coagulation models are superimposed on the liver tumors to obtain the abla...

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Section: Discussionmentioning

confidence: 99%

Characterization of 2450‐MHz microwave thermal coagulation zone based on characteristic length growth model and shape variation factor

Gao

Wang

et al. 2019

Int J RF Microw Comput Aided Eng

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“…Additionally, a statistically significant difference exists between the AV and IV (p = 0.008). The mean 18 F-FDG injection dose and the mean-estimated dose from PET/MR images were 7.13 ± 0.84 mCi/30 mL and 5.19 ± 0.60 mCi/30 mL, respectively. The retention rate ranged between 66.35% and 76.97%, and the mean retention rate percentage was 79.89% ± 4.22%.…”

Section: Analysis Of Ablation Zone Of the Livermentioning

confidence: 94%

“…The power passively decreases to <10 W when tissue impedance rises above 200 Ω. Simultaneously, 18 F-fluorodeoxyglucose ( 18 F-FDG) was slowly injected into the liver by an automatic infusion syringe at a speed of 3 cm 3 /min to evaluate the spread of 18 F-FDG by positron emission tomography (PET)/magnetic resonance imaging (MRI) examination (Figure 3c). After the RF energy was fully delivered for 10 min in the penetrated liver parenchyma, all electrodes were slowly removed when the electrode temperature reached approximately 70 • C to prevent tract bleeding along the tip.…”

Section: In Vivo Drug-releasing Rfa Proceduresmentioning

confidence: 99%

“…The ablated portion was analyzed by the PET/MRI examination to investigate whether 18 F-FDG was exactly released and diffused. For this process, a commercial sequential nanoScan ® PET/MRI system (Mediso Ltd., Hungary, Budapest) with 18 F-FDG was utilized to evaluate the drug that had been locally delivered on the ablation zone. The total acquisition time for PET/MRI was 40 min.…”

Section: Ex Vivo Pet/mri Examinationmentioning

confidence: 99%

“…Moreover, the retention rate was defined as the ratio of the 18 F-FDG radioactivity concentration derived from the PET/MRI images as follows: retention rate = (estimated dose/injection dose) × 100. Furthermore, to calculate the image volumes (IV) of 18 F-FDG uptake in the liver and measure the standard uptake value (SUV), the regions of interest were drawn manually and measured by one experienced nuclear medicine physician. The SUV was calculated as follows:…”

Section: Measurement Of the Ablation Zonementioning

confidence: 99%

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Feasibility of a Drug-Releasing Radiofrequency Ablation System in a Porcine Liver Model

et al. 2021

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The objective of this study was to investigate the feasibility of a newly developed anticancer drug-releasing radiofrequency ablation (RFA) system in a porcine liver model. A 15-gauge drug-releasing cooled wet electrode (DRCWE) was newly developed to improve the RFA efficacy for creating a large ablation as well as for simultaneously delivering an anticancer drug to the tumor margin. Nine ablations in three pigs were performed by the DRCWE. The sectioned liver specimens were evaluated by measuring the ablation zone by a positron emission tomography/magnetic resonance imaging examination to investigate whether 18F-fluorodeoxyglucose was exactly diffused. Volumes of the ablation zones released drug injection volumes, circularity, retention rate defined as the ratio between an estimated and injection dose, and the standard uptake value were assessed. The drug-releasing RFA was technically successful without procedural-related complications. During the procedure, the color changes of the ablated zones of the liver were observed in all specimens. The mean drug injection volume was higher than the ablated volumes (17.21 ± 2.85 vs 15.22 ± 2.30 cm3) and the circularity was 0.72 ± 0.08. Moreover, the retention rate was 72.89% ± 4.22% and the mean standard uptake value was 0.44 ± 0.05. The drug-releasing RFA system was feasible not only for local ablation but also for the delivery of anticancer drugs. The results of this study indicate that this novel strategy of localized RFA with a drug delivery system could be a promising option for the prevention of local recurrence rates.

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Study of flow effects on temperature‐controlled radiofrequency ablation using phantom experiments and forward simulations

et al. 2021

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Radiofrequency Ablation with an Internally Cooled Monopolar Directional Electrode: Ex Vivo and in Vivo Experimental Studies in the Liver

Abstract: Use of an ICDE can create a sufficient ablation in the desired direction and can decrease thermal injury to the adjacent organs.

Cited by 11 publications

References 32 publications

Characterization of 2450‐MHz microwave thermal coagulation zone based on characteristic length growth model and shape variation factor

Characterization of 2450‐MHz microwave thermal coagulation zone based on characteristic length growth model and shape variation factor

Feasibility of a Drug-Releasing Radiofrequency Ablation System in a Porcine Liver Model

Study of flow effects on temperature‐controlled radiofrequency ablation using phantom experiments and forward simulations

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