基于静态与动态电导率的组织不可逆电穿孔电-热耦合场及消融效果分析

不可逆电穿孔肿瘤消融治疗前对组织内部电-热耦合场的分析计算是实现肿瘤组织有效消融的关键所在,但目前对于多针系统下考虑组织电导率动态变化的真实组织内部电–热耦合场分布还缺乏系统研究。为此,首先通过二维有限元模型,量化分析了静态电导率与动态电导率模型下组织电场分布与电导率分布的差异。随后,根据患者肿瘤医学影像,重建了包含肿瘤的肾脏组织三维模型,研究了多脉冲下电–热耦合场分布及消融效果。研究结果表明,相同脉冲参数下,动态电导率模型得到的消融尺寸在垂直于电场方向上始终大于静态电导率模型;平行于电场方向上,随着场强的增大,动态电导率模型的消融尺寸出现先小于后大于静态电导率模型的现象,且动态电导率模型计算得到的消融面积(或体积)均更大;动态电导率模型下的组织温度分布同样显著区别于静态电导率模型。因此,采用动态电导率模型进行术前的治疗参数确定有利于达到最佳的肿瘤消融效果,并最大限度地降低对正常组织的损伤。

Analysis of Electrothermal-thermal Coupling Field and Ablation Effect of Tissue Irreversible Electroporation Based on Static and Dynamic Conductivity

The analysis and calculation of the electric-thermal coupling field inside the tissue before irreversible electroporation tumor ablation treatment is the key technology to achieve effective ablation of tumor tissues,but there is currently no systematic study of coupled field distribution of true internal tissue electric heating,considering the dynamic change of tissue conductivity in a multi-electrode system.Therefore,in this paper,a two-dimensional finite element model was first used to quantitatively analyze the difference between the electric field distribution and the conductivity distribution of the tissue under the static and dynamic conductivity models.Subsequently,according to the medical image of the patient’s tumor,a three-dimensional model of the kidney tissue containing the tumor was reconstructed,and the electric-thermal coupling field distribution and ablation effect under multiple pulses were studied.The results show that,under the same pulse parameters,the ablation size obtained by the dynamic conductivity model is always larger than that by the static conductivity model perpendicular to the electric field direction;parallel to the electric field direction,as the field strength increases,the ablation size of dynamic conductivity model becomes smaller first and then larger compared to that of static conductivity model,and the ablation area(or volume)calculated by the dynamic conductivity model is larger;the tissue temperature distribution under the dynamic conductivity model is also significantly different from that under the static conductivity model.Therefore,the use of a dynamic conductivity model to determine the treatment parameters before surgery is beneficial to achieving the best tumor ablation effect and minimizing the damage to normal tissues.