胸部真实边界的肺通气电阻抗变化动态仿真研究

Dynamic simulating on impedance changes of lung ventilation in chest model with real shape

目的:利用计算机仿真得到肺部在生理、病理状态下,肺通气、肺气肿和肺部肿瘤发展过程引起的体表电阻抗改变,为胸部的阻抗成像技术提供理论指导。方法:利用COMSOL Multi-physics多物理场计算平台,以胸部CT图像为依据,建立二维真实边界的胸部电阻抗动态变化模型,体表电极16个、激励电流0.5 mA,对向驱动临近测量模式,通过参数动态扫描,仿真获得肺通气、不同面积的单侧肺气肿及不同程度的肺肿瘤发生时,阻抗测量中胸部体表电极上的电位变化情况。结果:肺通气量和肺气肿面积增大时,引起肺整体或局部电导率降低,从而导致体表相邻电极的电势差绝对值增大;肺肿瘤引起局部电导率增大,导致相邻电极的电势差绝对值减小。结论:利用现有的软件平台,基于参数扫描方法,可直观地对胸部及组织生理、病理的参数变化引起的阻抗改变进行动态仿真,为胸部阻抗成像的定性和定量分析打下了基础,也为脑部、腹部阻抗成像的动态仿真研究提供了有效的方法。

Objective Through computer simulation to obtain surface electrical impedance changes in lung under physiological and pathological conditions, such as lung ventilation, pulmonary emphysema and lung tumor development processes, etc, so as to provide theoretical guidance for chest electrical impedance tomography （EIT）. Methods With COMSOL Multi-physics computing platform and chest CT images, the two-dimensional chest electrical impedance dyn- amic change model was built up with real boundary, with 16 surface electrodes, 0.5 mA driving current and polar- driving adjacent-measuring mode. Through dynamic parameter scanning （DPS） method, the potential changes of surface electrodes during chest impedance measurement were obtained by dynamically simulating the lung ventilation, unilateral pulmonary emphysema with different sizes and lung tumor with different stages. Results The volume increasing of lung ventilation and pulmonary emphysema led the total or local lung conductivity decreasing, thus caused the abstract value of the potential differences between adjacent electrodes increased, while lung tumor led local lung conductivity increasing, and that of the potential differences between adjacent electrodes decreased. Concluslon Based on the software platform and the DPS method, the impedance changes caused by chest and tissue＇s physiological or pathological parameters can be simulated directly, which not only lays a foundation of qualitative and quantitative analysis of the chest EIT, but also provides an effective method for dynamic simulation of brain and abdominal EIT.