Radai M M, Abboud S, Rubinsky B
Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel.
Cryobiology. 1999 Feb;38(1):51-9. doi: 10.1006/cryo.1998.2148.
Bioimpedance is a noninvasive technique that produces information on the electrical characteristics of tissue inside the body from currents injected and electrical potentials measured on the surface of the body. Because freezing causes a large increase in tissue electrical impedance we thought that it may also cause significant changes in the surface electrical potential making the bioimpedance technique suitable for noninvasive monitoring and imaging of cryosurgery. To evaluate the feasibility of the bioimpedance technique in cryosurgery we examined, as a case study, a theoretical model for the electrical potentials during brain cryosurgery. A three-dimensional spherical model was used to calculate the change in the electrical potential distribution in the head as a function of the current source location and the size of the frozen lesion in the brain. The numerical calculations were executed using the finite volume method and the iterative successive over relaxation method. The results demonstrate that, indeed, freezing inside the head produces measurable changes in the electrical potential on the outer surface-the scalp.
生物电阻抗是一种非侵入性技术，它通过注入体内的电流和在体表测量的电位来获取有关体内组织电特性的信息。由于冷冻会导致组织电阻抗大幅增加，我们认为它也可能引起表面电位的显著变化，从而使生物电阻抗技术适用于冷冻手术的非侵入性监测和成像。为了评估生物电阻抗技术在冷冻手术中的可行性，我们作为一个案例研究，研究了脑部冷冻手术期间电位的理论模型。使用三维球形模型来计算头部电位分布的变化，该变化是电流源位置和脑部冷冻损伤大小的函数。数值计算使用有限体积法和迭代逐次超松弛法进行。结果表明，确实，头部内部的冷冻会在头皮外表面产生可测量的电位变化。
