Roll-Off Displacement in <i>Ex Vivo</i> Experiments of RF Ablation With Refrigerated Saline Solution and Refrigerated Deionized Water

Fonseca, Ronei Delfino da; Monteiro, Melissa Silva; Marques, Marina Pinheiro; Motta, B.C.; Guimarães, Guilherme dos Anjos; Santos, Paulo Roberto; Jacobi, Ricardo Pezzuol; Rosa, Suélia de Siqueira Rodrigues Fleury

doi:10.1109/tbme.2018.2873141

Cited by 14 publications

(13 citation statements)

References 25 publications

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“…3(b), the pulsed RFA protocol results in the formation of alternating temperature spikes that are located between the lower and higher values pertaining to the duration and frequency of the applied pulse train, restricting or delaying the occurrence of charring. As mentioned earlier, the charring is highly undesirable phenomena during the RFA procedure that results in dramatic increase of the impedance and prevents the RF power generator from delivering further energy within the biological tissue [9,[25][26]. Different strategies are developed and adopted in clinical practices to either mitigate or delay the occurrence of charring during the RFA procedure by either modifying the RF delivery protocol or the RF electrode [10].…”

Section: Resultsmentioning

confidence: 99%

Computational Science – ICCS 2019

2019

Lecture Notes in Computer Science

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In this paper, a parametric study has been conducted to evaluate the effects of frequency and duration of the short burst pulses during pulsed radiofrequency ablation (RFA) in treating chronic pain. Affecting the brain and nervous system, this disease remains one of the major challenges in neuroscience and clinical practice. A two-dimensional axisymmetric RFA model has been developed in which a single needle radiofrequency electrode has been inserted. A finite-element-based coupled thermo-electric analysis has been carried out utilizing the simplified Maxwell's equations and the Pennes bioheat transfer equation to compute the electric field and temperature distributions within the computational domain. Comparative studies have been carried out between the continuous and pulsed RFA to highlight the significance of pulsed RFA in chronic pain treatment. The frequencies and durations of short burst RF pulses have been varied from 1 Hz to 10 Hz and from 10 ms to 50 ms, respectively. Such values are most commonly applied in clinical practices for mitigation of chronic pain. By reporting such critical input characteristics as temperature distributions for different frequencies and durations of the RF pulses, this computational study aims at providing the first-hand accurate quantitative information to the clinicians on possible consequences in those cases where these characteristics are varied during the pulsed RFA procedure. The results demonstrate that the efficacy of pulsed RFA is significantly dependent on the duration and frequency of the RF pulses.

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Section: Resultsmentioning

confidence: 99%

Computational Science – ICCS 2019

2019

Lecture Notes in Computer Science

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“…This may be due to two competing factors: 1) COS DW 100 has a lower dynamic viscosity, which leads to a larger distribution of cationic polymer solution than CMC DW 100 , and 2) CMC DW 100 has a higher electrical conductivity than COS DW 100 in the liver tissues. In addition, it is worth mentioning that, different from the saline solution (0.0007 Pa•s in dynamic viscosity), the higher dynamic viscosity of COS DW 100 (0.01 Pa•s) or CMC DW 100 (0.61 Pa•s) can limit the solution diffusion area, which may help to avoid large and irregular diffusion zones (see Supplementary Video (3)(4)(5)). Therefore, it is reasonable to believe that a regular and predictable ablation zone can be achieved using COS DW 100 or CMC DW 100 compared to the saline solution [41], [42].…”

Section: Discussionmentioning

confidence: 99%

“…However, when the tissue is heated above 100°C, it becomes desiccated due to water evaporation and further charred. In fact, the RFA systems currently used in clinical practice are designed such that the delivery of RF power is halted when an abrupt increase in impedance has been detected, a phenomenon known as "roll off" [4], [5]. Roll-off due to increased impedance is one of the main reasons for the incomplete ablation of large tumors treated by RFA.…”

Section: Introductionmentioning

confidence: 99%

A Novel Method to Increase Tumor Ablation Zones With RFA by Injecting the Cationic Polymer Solution to Tissues: In Vivo and Computational Studies

Fang

Möser

Zhang

et al. 2020

IEEE Trans. Biomed. Eng.

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This study aims to examine, for the first time, the introduction of cationic polymer solutions to improve radiofrequency ablation (RFA) in terms of a potentially enlarged ablation zone. Methods: By using in vivo and computational RFA studies, two cationic polymers, Chitooligosaccharides (COS) and carboxymethyl chitosan (CMC), diluted in deionized water, were injected into tissues separately surrounding the RF bipolar electrode prior to power application. A total of 9 rabbits were used to 1) measure the increase in electrical conductivity of tissues injected with the cationic polymer solutions, and 2) explore the enhancement of the ablation performance in RFA trials. A computer model of RFA comprising a model of the solution diffusion with an RF thermal ablation model was also built, validated by the in vivo experiment, to quantitatively study the effect of cationic polymer solutions on ablation performances. Results: Compared to the control group, the electrical conductivity of rabbit liver tissues was increased by 42.20% (0.282 ± 0.006 vs. 0.401 ± 0.048 S/m, P = 0.001) and 43.97% (0.282 ± 0.006 vs. 0.406 ± 0.042 S/m, P = 0.001) by injecting the COS and CMC solution at the concentration of 100 mg/mL into the tissues, denoted COS D W 100 and CMC D W 100 , respectively. Consequently, the in vivo experiments show that the ablation zone was enlarged by 95% (47.6 ± 6.3 vs. 92.6 ± 11.5 mm 2 , P <

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“…Although tissue impedance decreases as heating begins, the dehydration of the target region caused by the vaporization of moisture leads to an increase in impedance [ 19 ]. As a result of tissue carbonization, the expansion of the coagulation volume is limited, which compromises the effectiveness of the RFA procedure and exacerbates the roll-off phenomenon [ 37 ].…”

Section: Introductionmentioning

confidence: 99%

Particle swarm optimization solution for roll-off control in radiofrequency ablation of liver tumors: Optimal search for PID controller tuning

Faria,

Rosa,

Nunes

et al. 2024

PLoS ONE

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The study investigates the efficacy of a bioinspired Particle Swarm Optimization (PSO) approach for PID controller tuning in Radiofrequency Ablation (RFA) for liver tumors. Ex-vivo experiments were conducted, yielding a 9th order continuous-time transfer function. PSO was applied to optimize PID parameters, achieving outstanding simulation results: 0.605% overshoot, 0.314 seconds rise time, and 2.87 seconds settling time for a unit step input. Statistical analysis of 19 simulations revealed PID gains: Kp (mean: 5.86, variance: 4.22, standard deviation: 2.05), Ki (mean: 9.89, variance: 0.048, standard deviation: 0.22), Kd (mean: 0.57, variance: 0.021, standard deviation: 0.14) and ANOVA analysis for the 19 experiments yielded a p-value ≪ 0.05. The bioinspired PSO-based PID controller demonstrated remarkable potential in mitigating roll-off effects during RFA, reducing the risk of incomplete tumor ablation. These findings have significant implications for improving clinical outcomes in hepatocellular carcinoma management, including reduced recurrence rates and minimized collateral damage. The PSO-based PID tuning strategy offers a practical solution to enhance RFA effectiveness, contributing to the advancement of radiofrequency ablation techniques.

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Roll-Off Displacement in Ex Vivo Experiments of RF Ablation With Refrigerated Saline Solution and Refrigerated Deionized Water

Cited by 14 publications

References 25 publications

Computational Science – ICCS 2019

Computational Science – ICCS 2019

A Novel Method to Increase Tumor Ablation Zones With RFA by Injecting the Cationic Polymer Solution to Tissues: In Vivo and Computational Studies

Particle swarm optimization solution for roll-off control in radiofrequency ablation of liver tumors: Optimal search for PID controller tuning

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