Kos Bor, Voigt Peter, Miklavcic Damijan, Moche Michael
University of Ljubljana, Faculty of Electrical Engineering, Ljubljana, Slovenia.
Leipzig University Hospital, Department of Diagnostic and Interventional Radiology, Leipzig, Germany.
Radiol Oncol. 2015 Aug 21;49(3):234-41. doi: 10.1515/raon-2015-0031. eCollection 2015 Sep.
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.
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.
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.
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.
不可逆电穿孔（IRE）是一种组织消融方法，它依赖于电穿孔现象。当细胞暴露于足够强的电场时，质膜会被破坏，细胞会经历凋亡或坏死性细胞死亡。尽管已知存在热效应，但IRE被认为是非热消融技术，目前应用于热消融技术禁忌部位的肿瘤治疗。
IRE唯一商用脉冲发生器的制造商建议，在肝脏肿瘤治疗中，电压与距离的比值为1500至1700V/cm。然而，主要血管会影响电场分布。我们提出了一种IRE治疗计划方法，该方法考虑了血管对电场的影响；这在一名48岁患者的治疗中得到了说明，该患者在右侧半肝切除术后，在剩余肝静脉附近有转移瘤。
数值治疗计划方法的输出结果显示，产生了一个19.9cm³的不可逆电穿孔病灶，整个肿瘤至少被900V/cm的电场覆盖。这与IRE治疗后增强CT图像中所见的低密度病灶体积相比良好。电极附近出现明显的温度升高。然而，治疗后肝静脉保持通畅，6个月后无肿瘤复发迹象。
使用精确计算机模型进行治疗计划被认为对电化学疗法和不可逆电穿孔很重要。本研究的一个重要发现是，电极表面会显著升温。因此，临床使用者在遵循制造商建议时，通常应避免将电极放置在距离危险结构小于4mm的位置。
