Gergel Alexander, Zlochiver Sharon, Rosenfeld Moshe, Abboud Shimon
Department of Biomedical Engineering, Faculty of Engineering, Tel-Aviv University, Tel-Aviv 69978, Israel.
IEEE Trans Biomed Eng. 2005 Jul;52(7):1361-5. doi: 10.1109/TBME.2005.847524.
In the noninvasive bio-impedance technique, small amplitude currents are applied to the body and the developing potentials on its surface are measured. This noninvasive technique is used to monitor physiological and pathological processes, which alter the values or the spatial distribution of the electrical impedance inside the human body. A possible application of the bio-impedance technique is monitoring brain cryosurgery procedure--a surgical technique that employs freezing to destroy undesirable tissues. A numerical solver was developed to evaluate the ability of an induced-current bio-impedance system to monitor the growth of the frozen tissue inside the head in simulation. The forward-problem bio-impedance solver, which is based on the finite volume method in generalized two-dimensional (2-D) coordinate systems, was validated by a comparison to a known analytical solution for body-fitted and Cartesian meshing grids. The sensitivity of the developed surface potential to the ice-ball area was examined using a 2-D head model geometry, and was found to range between 0.8 x 10(-2) and 1.68 x 10(-2) (relative potential difference/mm2), depending on the relative positioning of the excitation coil and the head. The maximal sensitivity was achieved when the coil was located at the geometrical center of the model.
在无创生物阻抗技术中，向人体施加小幅度电流，并测量其表面产生的电位。这种无创技术用于监测生理和病理过程，这些过程会改变人体内部电阻抗的值或空间分布。生物阻抗技术的一个可能应用是监测脑部冷冻手术过程——一种采用冷冻来破坏不良组织的外科技术。开发了一种数值求解器，以评估感应电流生物阻抗系统在模拟中监测头部内部冷冻组织生长的能力。基于广义二维（2-D）坐标系中的有限体积法的正向问题生物阻抗求解器，通过与已知的适体和笛卡尔网格剖分的解析解进行比较而得到验证。使用二维头部模型几何结构检查了所开发的表面电位对冰球区域的灵敏度，发现其范围在0.8×10⁻²至1.68×10⁻²（相对电位差/平方毫米）之间，这取决于激励线圈与头部的相对位置。当线圈位于模型的几何中心时，可实现最大灵敏度。
