## 4 Discussion
The changing characteristics of the electrical conductivity during an electroporation treatment are often taken into consideration in the numerical calculations by spatially updating the electrical conductivity, mainly, as a function of electric field solely, or electric field and temperature [8; 12; 22; 35; 36; 37]. Thus, in future studies, further investigations should be conducted into the incorporation of the heterogeneous dynamic spatial changes in the electrical conductivity during electroporation in EPE, and investigate the effect on the electric field distributions. Note that in Section 2.4. Application in Heterogeneous Tumor Models, the electric-potential values of EPE were assumed to be constant along the longitudinal axis of the electrodes. In addition, these values were only varied along transversal planes of the electrodes. However, the electric-potential distributions would vary along the longitudinal axis of the electrode when a relatively short electrode is utilized with a length in the order of the distance between the electrodes, [23; 38]. In future studies, this can be addressed, for example, by multiplying the EPE values with a function that estimates the electric-potential distribution along the longitudinal axis of the electrodes. Further research should be performed to determine a reliable estimation. IRE is a relatively novel ablation technique, and most of the simulation studies published use idealized conditions which assume homogeneous tissue properties and perfectly parallel alignment of the electrodes, which are not representative of realistic clinical conditions [12]. Some validation studies have been performed to achieve robust treatment planning suitable for introduction in the clinical practice [39; 40]. Considering various quantities and parameters (e.g., electrode configuration and electrical conductivity dependence on electric field and temperature) during such validation processes, the EPE can significantly reduce the calculation time, allowing for the inclusion of additional parameters for further improvement of the accuracy. In addition, due to the reduction in calculation time, the inclusion of EPE makes it possible to perform personalized IRE treatment planning as it is possible to evaluate several different treatment plan options using the most recently registered patient images shortly prior to IRE treatment delivery, or even after the electrode implantation is performed. This increases the likelihood of an optimal treatment delivery and more accurate prediction of the treated region and measured quantities, such as electrical current and resistance, which can be compared with the actual values during treatment delivery. Fast EPE-based low-resolution planning can also be clinically applied for a more reliable assessment of the size of the possible thermal ablation region in the high field region close to the electrode [12], for assessing the IRE effect close to specific structures in the treatment region (e.g., bile ducts, blood vessels, etc.) [41], and to assess the most favorable needle orientation in the presence of stents or other small metallic structures that may present a risk on local thermal damage [5; 42]. Further research should be performed to determine the reliability of the assessment of fast low-resolution EPE in these clinical applications.