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The optimization of needle electrode number and placement for irreversible electroporation of hepatocellular carcinoma.

Adeyanju OO, Al-Angari HM, Sahakian AV - Radiol Oncol (2012)

Bottom Line: We also found the distance between electrodes was far more important in influencing the outcome measures when compared with the depth of electrode insertion.Overall, the distribution of electric field is highly dependent upon the electrode configuration, but the optimal configuration can be determined using numerical modeling.Our findings can help guide the clinical application of IRE as well as the selection of the best optimization algorithm to use in finding the optimal electrode configuration.

View Article: PubMed Central - PubMed

ABSTRACT

Background: Irreversible electroporation (IRE) is a novel ablation tool that uses brief high-voltage pulses to treat cancer. The efficacy of the therapy depends upon the distribution of the electric field, which in turn depends upon the configuration of electrodes used.

Methods: We sought to optimize the electrode configuration in terms of the distance between electrodes, the depth of electrode insertion, and the number of electrodes. We employed a 3D Finite Element Model and systematically varied the distance between the electrodes and the depth of electrode insertion, monitoring the lowest voltage sufficient to ablate the tumor, V(IRE). We also measured the amount of normal (non-cancerous) tissue ablated. Measurements were performed for two electrodes, three electrodes, and four electrodes. The optimal electrode configuration was determined to be the one with the lowest V(IRE), as that minimized damage to normal tissue.

Results: The optimal electrode configuration to ablate a 2.5 cm spheroidal tumor used two electrodes with a distance of 2 cm between the electrodes and a depth of insertion of 1 cm below the halfway point in the spherical tumor, as measured from the bottom of the electrode. This produced a V(IRE) of 3700 V. We found that it was generally best to have a small distance between the electrodes and for the center of the electrodes to be inserted at a depth equal to or deeper than the center of the tumor. We also found the distance between electrodes was far more important in influencing the outcome measures when compared with the depth of electrode insertion.

Conclusions: Overall, the distribution of electric field is highly dependent upon the electrode configuration, but the optimal configuration can be determined using numerical modeling. Our findings can help guide the clinical application of IRE as well as the selection of the best optimization algorithm to use in finding the optimal electrode configuration.

No MeSH data available.


Related in: MedlinePlus

Cross section of the tumor (circle) and its ablation zone (blue) at an applied voltage of 5.05 kV, which corresponds to the VIRE for two electrodes at a distance of 2.5 cm and depth of 1 cm for A) two electrodes B) three electrodes C) four electrodes D) three electrodes with the center of the electrodes shifted to the right 1 cm Note the asymmetry in B and the narrowing of the ablation zone in C. A bounding box around the tumor was used in the FEM simulations to improve the quality of the meshing and computations.
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f3-rado-46-02-126: Cross section of the tumor (circle) and its ablation zone (blue) at an applied voltage of 5.05 kV, which corresponds to the VIRE for two electrodes at a distance of 2.5 cm and depth of 1 cm for A) two electrodes B) three electrodes C) four electrodes D) three electrodes with the center of the electrodes shifted to the right 1 cm Note the asymmetry in B and the narrowing of the ablation zone in C. A bounding box around the tumor was used in the FEM simulations to improve the quality of the meshing and computations.

Mentions: To visualize the differing ablation zones for the different electrode configurations, we examined a cross section of the center of the tumor, demarcating regions that were greater than or equal to 680 V/cm for two, three, and four electrodes at a distance of 2.5 cm and a depth of 1 cm and plotted the ablation zones in Figure 3. Due to the asymmetric ablation shape with three-electrode configuration we tried moving the center of the electrode array and checked whether this would lower VIRE and VANT (Figure 3D). In fact this, lowered VIRE and VANT from 9200 V and 38.4 cm3 to 4600 V and 16.3 cm3 respectively when moving the center of the electrode array 1 cm to the right of the center of the tumor.


The optimization of needle electrode number and placement for irreversible electroporation of hepatocellular carcinoma.

Adeyanju OO, Al-Angari HM, Sahakian AV - Radiol Oncol (2012)

Cross section of the tumor (circle) and its ablation zone (blue) at an applied voltage of 5.05 kV, which corresponds to the VIRE for two electrodes at a distance of 2.5 cm and depth of 1 cm for A) two electrodes B) three electrodes C) four electrodes D) three electrodes with the center of the electrodes shifted to the right 1 cm Note the asymmetry in B and the narrowing of the ablation zone in C. A bounding box around the tumor was used in the FEM simulations to improve the quality of the meshing and computations.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3472940&req=5

f3-rado-46-02-126: Cross section of the tumor (circle) and its ablation zone (blue) at an applied voltage of 5.05 kV, which corresponds to the VIRE for two electrodes at a distance of 2.5 cm and depth of 1 cm for A) two electrodes B) three electrodes C) four electrodes D) three electrodes with the center of the electrodes shifted to the right 1 cm Note the asymmetry in B and the narrowing of the ablation zone in C. A bounding box around the tumor was used in the FEM simulations to improve the quality of the meshing and computations.
Mentions: To visualize the differing ablation zones for the different electrode configurations, we examined a cross section of the center of the tumor, demarcating regions that were greater than or equal to 680 V/cm for two, three, and four electrodes at a distance of 2.5 cm and a depth of 1 cm and plotted the ablation zones in Figure 3. Due to the asymmetric ablation shape with three-electrode configuration we tried moving the center of the electrode array and checked whether this would lower VIRE and VANT (Figure 3D). In fact this, lowered VIRE and VANT from 9200 V and 38.4 cm3 to 4600 V and 16.3 cm3 respectively when moving the center of the electrode array 1 cm to the right of the center of the tumor.

Bottom Line: We also found the distance between electrodes was far more important in influencing the outcome measures when compared with the depth of electrode insertion.Overall, the distribution of electric field is highly dependent upon the electrode configuration, but the optimal configuration can be determined using numerical modeling.Our findings can help guide the clinical application of IRE as well as the selection of the best optimization algorithm to use in finding the optimal electrode configuration.

View Article: PubMed Central - PubMed

ABSTRACT

Background: Irreversible electroporation (IRE) is a novel ablation tool that uses brief high-voltage pulses to treat cancer. The efficacy of the therapy depends upon the distribution of the electric field, which in turn depends upon the configuration of electrodes used.

Methods: We sought to optimize the electrode configuration in terms of the distance between electrodes, the depth of electrode insertion, and the number of electrodes. We employed a 3D Finite Element Model and systematically varied the distance between the electrodes and the depth of electrode insertion, monitoring the lowest voltage sufficient to ablate the tumor, V(IRE). We also measured the amount of normal (non-cancerous) tissue ablated. Measurements were performed for two electrodes, three electrodes, and four electrodes. The optimal electrode configuration was determined to be the one with the lowest V(IRE), as that minimized damage to normal tissue.

Results: The optimal electrode configuration to ablate a 2.5 cm spheroidal tumor used two electrodes with a distance of 2 cm between the electrodes and a depth of insertion of 1 cm below the halfway point in the spherical tumor, as measured from the bottom of the electrode. This produced a V(IRE) of 3700 V. We found that it was generally best to have a small distance between the electrodes and for the center of the electrodes to be inserted at a depth equal to or deeper than the center of the tumor. We also found the distance between electrodes was far more important in influencing the outcome measures when compared with the depth of electrode insertion.

Conclusions: Overall, the distribution of electric field is highly dependent upon the electrode configuration, but the optimal configuration can be determined using numerical modeling. Our findings can help guide the clinical application of IRE as well as the selection of the best optimization algorithm to use in finding the optimal electrode configuration.

No MeSH data available.


Related in: MedlinePlus