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A parametric study delineating irreversible electroporation from thermal damage based on a minimally invasive intracranial procedure.

Garcia PA, Rossmeisl JH, Neal RE, Ellis TL, Davalos RV - Biomed Eng Online (2011)

Bottom Line: We developed numerical simulations of typical protocols based on a previously published computed tomographic (CT) guided in vivo procedure.We confirm that determining an IRE treatment protocol requires incorporating all the physical effects of electroporation, and that these effects may have significant implications in treatment planning and outcome assessment.The goal of the manuscript is to provide the reader with the numerical methods to assess multiple-pulse electroporation treatment protocols in order to isolate IRE from thermal damage and capitalize on the benefits of a non-thermal mode of tissue ablation.

View Article: PubMed Central - HTML - PubMed

Affiliation: Bioelectromechanical Systems Laboratory, School of Biomedical Engineering and Sciences, Virginia Tech-Wake Forest University, Blacksburg, VA, USA.

ABSTRACT

Background: Irreversible electroporation (IRE) is a new minimally invasive technique to kill undesirable tissue in a non-thermal manner. In order to maximize the benefits from an IRE procedure, the pulse parameters and electrode configuration must be optimized to achieve complete coverage of the targeted tissue while preventing thermal damage due to excessive Joule heating.

Methods: We developed numerical simulations of typical protocols based on a previously published computed tomographic (CT) guided in vivo procedure. These models were adapted to assess the effects of temperature, electroporation, pulse duration, and repetition rate on the volumes of tissue undergoing IRE alone or in superposition with thermal damage.

Results: Nine different combinations of voltage and pulse frequency were investigated, five of which resulted in IRE alone while four produced IRE in superposition with thermal damage.

Conclusions: The parametric study evaluated the influence of pulse frequency and applied voltage on treatment volumes, and refined a proposed method to delineate IRE from thermal damage. We confirm that determining an IRE treatment protocol requires incorporating all the physical effects of electroporation, and that these effects may have significant implications in treatment planning and outcome assessment. The goal of the manuscript is to provide the reader with the numerical methods to assess multiple-pulse electroporation treatment protocols in order to isolate IRE from thermal damage and capitalize on the benefits of a non-thermal mode of tissue ablation.

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Electric conductivity of tissue as a function of the local electric field. This plot was determined by the flc2hs Heaviside function. The conductivity changes from a baseline σ0 = 0.256 S/m to σ = 3.0 · σ0 = 0.767 S/m at the onset of the IRE pulses. Note: We assumed that once the conductivity increased due to electroporation it would not revert back.
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Figure 3: Electric conductivity of tissue as a function of the local electric field. This plot was determined by the flc2hs Heaviside function. The conductivity changes from a baseline σ0 = 0.256 S/m to σ = 3.0 · σ0 = 0.767 S/m at the onset of the IRE pulses. Note: We assumed that once the conductivity increased due to electroporation it would not revert back.

Mentions: where σ0 is the baseline conductivity, α the temperature coefficient, T the temperature, and T0 the physiological temperature [22]. Figure 3 displays the smoothed Heaviside function, flc2hs, with a continuous second derivative that ensures convergence of the numerical solution. This function is defined in Comsol, and it changes from zero to one when normE_dc - Edelta = 0 over the range ± Erange [22].


A parametric study delineating irreversible electroporation from thermal damage based on a minimally invasive intracranial procedure.

Garcia PA, Rossmeisl JH, Neal RE, Ellis TL, Davalos RV - Biomed Eng Online (2011)

Electric conductivity of tissue as a function of the local electric field. This plot was determined by the flc2hs Heaviside function. The conductivity changes from a baseline σ0 = 0.256 S/m to σ = 3.0 · σ0 = 0.767 S/m at the onset of the IRE pulses. Note: We assumed that once the conductivity increased due to electroporation it would not revert back.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3108916&req=5

Figure 3: Electric conductivity of tissue as a function of the local electric field. This plot was determined by the flc2hs Heaviside function. The conductivity changes from a baseline σ0 = 0.256 S/m to σ = 3.0 · σ0 = 0.767 S/m at the onset of the IRE pulses. Note: We assumed that once the conductivity increased due to electroporation it would not revert back.
Mentions: where σ0 is the baseline conductivity, α the temperature coefficient, T the temperature, and T0 the physiological temperature [22]. Figure 3 displays the smoothed Heaviside function, flc2hs, with a continuous second derivative that ensures convergence of the numerical solution. This function is defined in Comsol, and it changes from zero to one when normE_dc - Edelta = 0 over the range ± Erange [22].

Bottom Line: We developed numerical simulations of typical protocols based on a previously published computed tomographic (CT) guided in vivo procedure.We confirm that determining an IRE treatment protocol requires incorporating all the physical effects of electroporation, and that these effects may have significant implications in treatment planning and outcome assessment.The goal of the manuscript is to provide the reader with the numerical methods to assess multiple-pulse electroporation treatment protocols in order to isolate IRE from thermal damage and capitalize on the benefits of a non-thermal mode of tissue ablation.

View Article: PubMed Central - HTML - PubMed

Affiliation: Bioelectromechanical Systems Laboratory, School of Biomedical Engineering and Sciences, Virginia Tech-Wake Forest University, Blacksburg, VA, USA.

ABSTRACT

Background: Irreversible electroporation (IRE) is a new minimally invasive technique to kill undesirable tissue in a non-thermal manner. In order to maximize the benefits from an IRE procedure, the pulse parameters and electrode configuration must be optimized to achieve complete coverage of the targeted tissue while preventing thermal damage due to excessive Joule heating.

Methods: We developed numerical simulations of typical protocols based on a previously published computed tomographic (CT) guided in vivo procedure. These models were adapted to assess the effects of temperature, electroporation, pulse duration, and repetition rate on the volumes of tissue undergoing IRE alone or in superposition with thermal damage.

Results: Nine different combinations of voltage and pulse frequency were investigated, five of which resulted in IRE alone while four produced IRE in superposition with thermal damage.

Conclusions: The parametric study evaluated the influence of pulse frequency and applied voltage on treatment volumes, and refined a proposed method to delineate IRE from thermal damage. We confirm that determining an IRE treatment protocol requires incorporating all the physical effects of electroporation, and that these effects may have significant implications in treatment planning and outcome assessment. The goal of the manuscript is to provide the reader with the numerical methods to assess multiple-pulse electroporation treatment protocols in order to isolate IRE from thermal damage and capitalize on the benefits of a non-thermal mode of tissue ablation.

Show MeSH
Related in: MedlinePlus