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Y. Mandel, J. Pe'er, S. Frenkel, B. Rubinsky; Planning Treatment of Uveal Melanoma by Irreversible Electroporation Using Finite Element Model. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5754.
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Irreversible electroporation (IRE) is a novel tool for treating solid tumors by applying high electrical field pulses on the target tissue. Some of the advantages of this technique are its specificity for affecting cells and preserving connective tissue (e.g. sclera). However, since it is difficult to focus the electrical energy on the tumor, it is crucial to choose optimal treatment parameters. The goal of this study was to develop a mathematical model for evaluation of optimal electrode configuration and pulse parameters that will induce maximal tumor eradication using IRE.
A geometrical model of an eye with a 6 mm height uveal melanoma tumor was constructed. A 3D mesh (~ 8,000 elements) was created using Comsol Multiphysiscs Version 3.3. We simulated a treatment plan of electrical pulse while changing the position of electrodes (external, internal, adjacent), and the electrical conductance of the tumor, sclera and vitreous. Treatment protocol goal was to achieve an electrical field of 800 V/cm in at least 50 percent of tumor while monitoring for minimal electrical field other areas.
External surface electrode combined with an intravitreal ground electrode was found to achieve maximal tumor coverage with minimal pulse amplitude. Assuming a tumor conductance of 0.5 S/m, most of the tumor volume achieved the threshold using a pulse of less than 1000 V. However, in tumor with higher conductance, a significantly higher electrical pulse was needed in order to achieve treatment goal. When using only external electrodes placed on the sclera, achievement of treatment goals could be reached by using higher electrical pulse. The electrical field in the macular area were low (less than 10 V/cm).
Electrical field thresholds for irreversible electroporation can theoretically be reached in uveal melanoma using external as well as internal electrode configuration. Tumor conductance has a significant effect on treatment efficiency. The conductances of the sclera above the tumor and of the aqueous humor are of secondary importance. Human as well as animal studies are needed in order to explore the potential of IRE in treating uveal melanoma.
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