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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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Time history of the volumes of tissue exposed to temperatures greater than 43°C and 50°C. The IRE treatment used eighty pulses (50 μs) with pulse frequencies of A) 0.5 Hz (160 s), B) 1 Hz (80 s), and C) 4 Hz (20 s). The applied voltages were 500 V, 1000 V, and 1500 V for each frequency investigated.
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Figure 8: Time history of the volumes of tissue exposed to temperatures greater than 43°C and 50°C. The IRE treatment used eighty pulses (50 μs) with pulse frequencies of A) 0.5 Hz (160 s), B) 1 Hz (80 s), and C) 4 Hz (20 s). The applied voltages were 500 V, 1000 V, and 1500 V for each frequency investigated.

Mentions: The volumes of tissue presented in this section were used to calculate the percentage of the tissue that was treated with IRE in superposition with the thermal assessment and are given in parentheses. The curves in Figure 8 are calculated volumes of tissue exposed to temperatures greater than 43°C and 50°C. These values have been used for the assessment of potentially thermally damaging temperatures with 43°C being used for extended exposures and 50°C for instantaneous thermal damage [4]. Figure 8A shows that at the completion of the treatments using a 0.5 Hz pulse repetition rate, volumes of tissue exposed to temperatures greater than 43°C and 50°C were only achieved when delivering 1500 V, up to maximum volumes of 0.235 cm3 (20.7% - 43°C) and 0.002 cm3 (0.2% - 50°C). However, the effects of temperature become more significant when the pulses are delivered at a higher repetition rate, shown in Figure 8B for a frequency of 1 Hz (80 s for total treatment). Here, applying 1000 V resulted in 0.112 cm3 (15.8%) of the tissue exposed to temperatures greater than 43°C and 0.00 cm3 (0.0%) at 50°C, significantly lower than the 1500 V treatment, which had tissue volumes of 0.557 cm3 (48.1%) and 0.158 cm3 (13.7%) exposed to temperatures greater than 43°C and 50°C, respectively. In Figure 8C one can appreciate the drastic effects of further increasing the repetition rate to 4 Hz (20 s for total treatment). In this scenario, even 1000 V results in tissue heating above 50°C in 0.124 cm3 (16.9%) of tissue, and greater than 43°C in 0.335 cm3 (45.7%). Finally, for an applied voltage of 1500 V, the majority of the tissue will be heated to elevated temperatures, where 0.741 cm3 (57.2%) and 0.410 cm3 (31.7%) of tissue experiences temperatures greater than 43°C and 50°C, respectively.


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)

Time history of the volumes of tissue exposed to temperatures greater than 43°C and 50°C. The IRE treatment used eighty pulses (50 μs) with pulse frequencies of A) 0.5 Hz (160 s), B) 1 Hz (80 s), and C) 4 Hz (20 s). The applied voltages were 500 V, 1000 V, and 1500 V for each frequency investigated.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 8: Time history of the volumes of tissue exposed to temperatures greater than 43°C and 50°C. The IRE treatment used eighty pulses (50 μs) with pulse frequencies of A) 0.5 Hz (160 s), B) 1 Hz (80 s), and C) 4 Hz (20 s). The applied voltages were 500 V, 1000 V, and 1500 V for each frequency investigated.
Mentions: The volumes of tissue presented in this section were used to calculate the percentage of the tissue that was treated with IRE in superposition with the thermal assessment and are given in parentheses. The curves in Figure 8 are calculated volumes of tissue exposed to temperatures greater than 43°C and 50°C. These values have been used for the assessment of potentially thermally damaging temperatures with 43°C being used for extended exposures and 50°C for instantaneous thermal damage [4]. Figure 8A shows that at the completion of the treatments using a 0.5 Hz pulse repetition rate, volumes of tissue exposed to temperatures greater than 43°C and 50°C were only achieved when delivering 1500 V, up to maximum volumes of 0.235 cm3 (20.7% - 43°C) and 0.002 cm3 (0.2% - 50°C). However, the effects of temperature become more significant when the pulses are delivered at a higher repetition rate, shown in Figure 8B for a frequency of 1 Hz (80 s for total treatment). Here, applying 1000 V resulted in 0.112 cm3 (15.8%) of the tissue exposed to temperatures greater than 43°C and 0.00 cm3 (0.0%) at 50°C, significantly lower than the 1500 V treatment, which had tissue volumes of 0.557 cm3 (48.1%) and 0.158 cm3 (13.7%) exposed to temperatures greater than 43°C and 50°C, respectively. In Figure 8C one can appreciate the drastic effects of further increasing the repetition rate to 4 Hz (20 s for total treatment). In this scenario, even 1000 V results in tissue heating above 50°C in 0.124 cm3 (16.9%) of tissue, and greater than 43°C in 0.335 cm3 (45.7%). Finally, for an applied voltage of 1500 V, the majority of the tissue will be heated to elevated temperatures, where 0.741 cm3 (57.2%) and 0.410 cm3 (31.7%) of tissue experiences temperatures greater than 43°C and 50°C, respectively.

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