title: Careful treatment planning enables safe ablation of liver tumors adjacent to major blood vessels by percutaneous irreversible electroporation (IRE).
abstract: BACKGROUND
  Irreversible electroporation (IRE) is a tissue ablation method, which relies on the phenomenon of electroporation. When cells are exposed to a sufficiently electric field, the plasma membrane is disrupted and cells undergo an apoptotic or necrotic cell death. Although heating effects are known IRE is considered as non-thermal ablation technique and is currently applied to treat tumors in locations where thermal ablation techniques are contraindicated.
  
  
  METHODS
  The manufacturer of the only commercially available pulse generator for IRE recommends a voltage-to-distance ratio of 1500 to 1700 V/cm for treating tumors in the liver. However, major blood vessels can influence the electric field distribution. We present a method for treatment planning of IRE which takes the influence of blood vessels on the electric field into account; this is illustrated on a treatment of 48-year-old patient with a metastasis near the remaining hepatic vein after a right side hemi-hepatectomy.
  
  
  RESULTS
  Output of the numerical treatment planning method shows that a 19.9 cm3 irreversible electroporation lesion was generated and the whole tumor was covered with at least 900 V/cm. This compares well with the volume of the hypodense lesion seen in contrast enhanced CT images taken after the IRE treatment. A significant temperature raise occurs near the electrodes. However, the hepatic vein remains open after the treatment without evidence of tumor recurrence after 6 months.
  
  
  CONCLUSIONS
  Treatment planning using accurate computer models was recognized as important for electrochemotherapy and irreversible electroporation. An important finding of this study was, that the surface of the electrodes heat up significantly. Therefore the clinical user should generally avoid placing the electrodes less than 4 mm away from risk structures when following recommendations of the manufacturer.
authors.affiliation: University of Ljubljana, Faculty of Electrical Engineering, Ljubljana, Slovenia.
authors.forename: Bor
authors.initials: B
authors.lastname: Kos
authors.affiliation: Leipzig University Hospital, Department of Diagnostic and Interventional Radiology, Leipzig, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Voigt
authors.affiliation: University of Ljubljana, Faculty of Electrical Engineering, Ljubljana, Slovenia.
authors.forename: Damijan
authors.initials: D
authors.lastname: Miklavcic
authors.affiliation: Leipzig University Hospital, Department of Diagnostic and Interventional Radiology, Leipzig, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Moche
keywords: colorectal carcinoma; finite element method; irreversible electroporation; liver tumors