Intracranial Nonthermal Irreversible Electroporation: In Vivo Analysis
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Nonthermal irreversible electroporation (NTIRE) is a new minimally invasive technique to treat cancer. It is unique because of its nonthermal mechanism of tumor ablation. Intracranial NTIRE procedures involve placing electrodes into the targeted area of the brain and delivering a series of short but intense electric pulses. The electric pulses induce irreversible structural changes in cell membranes, leading to cell death. We correlated NTIRE lesion volumes in normal brain tissue with electric field distributions from comprehensive numerical models. The electrical conductivity of brain tissue was extrapolated from the measured in vivo data and the numerical models. Using this, we present results on the electric field threshold necessary to induce NTIRE lesions (495–510 V/cm) in canine brain tissue using 90 50-μs pulses at 4 Hz. Furthermore, this preliminary study provides some of the necessary numerical tools for using NTIRE as a brain cancer treatment. We also computed the electrical conductivity of brain tissue from the in vivo data (0.12–0.30 S/m) and provide guidelines for treatment planning and execution. Knowledge of the dynamic electrical conductivity of the tissue and electric field that correlates to lesion volume is crucial to ensure predictable complete NTIRE treatment while minimizing damage to surrounding healthy tissue.
KeywordsBrain cancer therapy Minimally invasive surgery Nonthermal ablation Tumor ablation Electropermeabilization Bioheat transfer Finite element analysis Electric field correlation Electrical conductivity
This work was supported in part by the Coulter Foundation. Davalos acknowledges support from NSF CBET-0933335 towards the modeling effort presented in the manuscript. The authors thank Gregory B. Daniel, Carolina Ricco, Dana Calicott, Barbara Kafka and Stephanie Milburn for their assistance in surgery and Lindsey Buracker and Chris Arena for their help in treatment planning.
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