Temperature-controlled and constant-power radio-frequency ablation: what affects lesion growth?

Jain, M.K.; Wolf, Patrick D.

doi:10.1109/10.804568

Cited by 72 publications

(77 citation statements)

References 19 publications

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“…Several studies have been conducted to describe lesion growth for radiofrequency ablation devices [2,[9][10][11][12]21,24,[29][30][34][35]. In the majority of these cases, markers such as temperature isotherms and thermal dosing are used as the primary measure for lesion size.…”

Section: Discussionmentioning

confidence: 99%

Considerations for Thermal Injury Analysis for RF Ablation Devices

Chang¹

2010

TOBEJ

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Abstract:Background: The estimation of lesion size is an integral part of treatment planning for the clinical applications of radiofrequency ablation. However, to date, studies have not directly evaluated the impact of different computational estimation techniques for predicting lesion size. In this study, we focus on three common methods used for predicting tissue injury: (1) iso-temperature contours, (2) Cumulative equivalent minutes, (3) Arrhenius based thermal injury. Methods:We created a geometric model of a multi-tyne ablation electrode and simulated thermal and tissue injury profiles that result from three calculation methods after 15 minutes exposure to a constant RF voltage source. A hybrid finite element technique was used to calculate temperature and tissue injury. Time-temperature curves were used in the assessment of iso-temperature thresholds and the method of cumulative equivalent minutes. An Arrhenius-based formulation was used to calculate sequential and recursive thermal injury to tissues. Results: The data demonstrate that while iso-temperature and cumulative equivalent minute contours are similar in shape, these two methodologies grossly over-estimate the amount of tissue injury when compared to recursive thermal injury calculations, which have previously been shown to correlate closely with in vitro pathologic lesion volume measurement. In addition, Arrhenius calculations that do not use a recursive algorithm result in a significant underestimation of lesion volume. The data also demonstrate that lesion width and depth are inadequate means of characterizing treatment volume for multi-tine ablation devices. Conclusions: Recursive thermal injury remains the most physiologically relevant means of computationally estimating lesion size for hepatic tumor applications. Iso-thermal and cumulative equivalent minute approaches may produce significant errors in the estimation of lesion size.

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Section: Discussionmentioning

confidence: 99%

Considerations for Thermal Injury Analysis for RF Ablation Devices

Chang¹

2010

TOBEJ

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“…The situation has been simplified by ignoring Q p and Q m as they are negligible for RF heating [19].…”

Section: A Description Of the Theoretical Modelmentioning

confidence: 99%

“…However, to our knowledge, the majority of the numerical models of RF heating using an active electrode include only a limited fragment of biological tissue and active electrode [17,19,22,26,[36][37][38][39]. Computer simulations have been carried out in all these cases in order to determine the appropriate model dimensions.…”

Section: H Electrical Conductivity Dispersionmentioning

confidence: 99%

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Radio-frequency heating of the cornea: theoretical model and in vitro experiments

Berjano

Sáiz

Ferrero

2002

IEEE Trans. Biomed. Eng.

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We present a theoretical model for the study of cornea heating with radiofrequency currents. This technique is used to reshape the cornea to correct refractive disorders. Our numerical model has allowed the study of the temperature distributions in the cornea and to estimate the dimensions of the lesion. The model incorporates a fragment of cornea, aqueous humor and the active electrode placed on the cornea surface. The finite element method has been used to calculate the temperature distribution in the cornea by solving a coupled electric-thermal problem. We analyzed by means of computer simulations the effect of: a) temperature influence on the tissue electrical conductivity, b) the dispersion of the biological characteristics, c) the anisotropy of the cornea thermal conductivity, d) the presence of the tear film, and e) the insertion depth of the active electrode in the cornea, and the results suggest that these effects have a significant influence on the temperature distributions and thereby on the lesion dimensions. However, the cooling of the aqueous humor in the endothelium or the realistic value of the cornea curvature did not have a significant effect on the temperature distributions.An experimental model based on the lesions created in rabbit eyes has been used in order to compare the theoretical and experimental results. There is a tendency towards the agreement between experimental and theoretical results, although we have observed that the theoretical model overestimates the lesion dimension.

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“…Certain factors are known to have an impact on lesion size, e.g. tissue characteristics [4], electrode-tissue contact characteristics [5][6][7][8][9][10], electrode size [10], arrangement [11][12][13][14] and position [15,16] of the temperature sensor embedded in the electrode. Conversely, it is also known that varying these characteristics would affect the performance of the temperature control system.…”

Section: Introductionmentioning

confidence: 99%

Could it be advantageous to tune the temperature controller during radiofrequency ablation? A feasibility study using theoretical models

Alba-Martínez

Trujillo

Blasco-Gimenez³

et al. 2011

International Journal of Hyperthermia

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electrode-tissue contact characteristics (insertion depth, cooling effect of circulating blood) and electrode characteristics (size, location and arrangement of the temperature sensor in the electrode). Results:The lesion dimensions and T max remained almost unchanged when the specific PI controller was used instead of one tuned for the standard case: T max varied less than 1.9ºC, lesion width less than 0.2 mm, and lesion depth less than 0.3 mm. As expected, we did observe a direct logical relationship between the response time of each controller and the transient value of electrode temperature. Conclusion:The results suggest that a PI controller designed for a standard case (such as that described in this study), could offer benefits under different tissue conditions, electrode-tissue contact, and electrode characteristics.

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Temperature-controlled and constant-power radio-frequency ablation: what affects lesion growth?

Cited by 72 publications

References 19 publications

Considerations for Thermal Injury Analysis for RF Ablation Devices

Considerations for Thermal Injury Analysis for RF Ablation Devices

Radio-frequency heating of the cornea: theoretical model and in vitro experiments

Could it be advantageous to tune the temperature controller during radiofrequency ablation? A feasibility study using theoretical models

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