一种颅脑EIT中多路电极/头皮接触阻抗的同步测量方法研究

摘要

目的:研究一种用于颅脑电阻抗断层成像(electrical impedance tomography,EIT)中多路电极/头皮接触阻抗的同步测量方法,为探索接触阻抗对成像的影响及其抑制方法提供支撑.方法:为系统引入一路参考电极,放置于被监测者的颈后部或头顶.在边界电压信号采集间隙,采用二电极法依次测量每一路成像电极与参考电极之间的阻抗值,以此分析多路接触阻抗的特性.并在已有颅脑EIT硬件系统的基础上进行改进,添加多路接触阻抗同步测量模块.结果:定标板测试结果表明,该模块测量误差小于1‰,10 h内测量结果的最大相对波动小于1‰.初步人体测试结果表明,该方法具备获取16路接触阻抗的空间一致性及时间稳定性信息的能力.结论:该方法具有较高的测量精度及稳定性,可满足颅脑EIT中多路接触阻抗信号的同步测量需求.%Objective To study a method for monitoring multichannel electrode-scalp contact impedances in electrical impedance tomography (EIT), and to provide support for exploring the impact of contact impedances on imaging and the suppression method.Methods A reference electrode was introduced for the system,placed on the back of the neck or the top of the head. In the spare time of boundary voltage signal acquisition phase, the method of two electrodes was adopted to measure the electrical impedance between each imaging electrode and reference electrode, which was used to analyze the characteristics of multichannel contact impedances.Based on the existing EIT hardware system,the module for monitoring multichannel contact impedance was implemented.Results The calibration board test showed that the measurement error of this method was less than 1‰,and the maximum relative fluctuation of the measurement result within 10 hours was less than 1‰. Preliminary human test indicated that this method had the ability to obtain two kinds of information about spatial consistency and temporal stability of 16-channel contact impedances. Conclusion This method has high accuracy and stability,so it meets the requirements of monitoring multichannel contact impedances in brain EIT.