在体兔脑组织电阻抗频率特性测量及电阻抗断层成像

背景电阻抗断层成像技术是对人体表施加无害电信号,体表测量其响应,用重构算法得到人体内部的电阻抗或其变化的分布图像.与现有的CT,MRI等技术相比,电阻抗断层成像技术具有实时性强、费用低廉、便于连续监测和功能成像等优势.目的在体测量兔脑组织在缺血前后的电阻抗频率特性,并对缺血脑组织进行电阻抗断层成像技术,验证电阻抗断层成像技术对脑功能变化成像的可能性.设计单一样本实验.单位解放军第四军医大生物医学工程系医学电子工程教研室.材料实验于2001-08/09在解放军第四军医大学生物医学工程系医学电子工程教研室电阻抗断层成像实验室完成.选择成年健康家兔10只用于实验.方法采用颈总动脉结扎法制造脑缺血动物模型,对缺血前后的脑组织电阻抗特性进行在体测量.利用电阻抗断层成像系统对单侧脑组织供血变化进行成像.主要观察指标①缺血前后的脑组织在0.1 Hz～1 MHz频率范围内电阻抗频率特性曲线.②单侧脑组织供血变化电阻抗断层成像结果.结果1只家兔钻透硬脑膜,9只家兔结果进入分析.①在缺血脑损伤发生后,脑阻抗明显增大,在10 Hz以下脑阻抗变化率可达75%,在1 kHz～1 MHz频率范围脑阻抗变化率约为15%且比较稳定.②初步的动态成像结果显示,脑组织供血变化一侧与其电阻率变化位置相一致.结论缺血前后脑组织阻抗变化率满足成像要求,可以将其作为一个成像变量.

In vivo measurement of the rabbit brain impedance frequency response and the elementary imaging of electrical impedance tomography

BACKGROUND: Electrical impedance tomography (EIT) uses non-invasive signals to probe the human body and then detect the responses on the boundary of the body in order to reconstruct an impedance distribution inside the body. Compared to CT and MRI, EIT takes the advantages of realtime technique, lower cost and easiness for both continuous monitoring and functional imaging.OBJECTIVE: This study was designed to perform the in vivo measurement of the rabbit brain impedance frequency response before and after ischemia. And it was to verify the feasibility of EIT in brain functional imaging by ischemia brain functional imaging using EIT.DESIGN: It was a single-sample experiment.SETTING: It was conducted at the Department of Medical Electronic Engineering, Faculty of Biomedical Engineering, Fourth Military Medical University of Chinese PLA.MATERIALS: This study was conducted at the Department of Medical Electronic Engineering, Faculty of Biomedical Engineering, Fourth Military Medical University of Chinese PLA from August to September 2001 and 10 healthy rabbits were selected.METHODS: Cerebral ischemia animal model was made using carotid artery ligation. Then the in vivo measurement of the rabbit brain impedance frequency response before and after ischemia was performed.Dynamic unilateral brain blood supply was recorded using EIT imaging.curves were plot before and after ischemia in the frequency range from 0.1 Hz EIT imagingRESULTS: Nine rabbits entered the statistical analysis and one was omitimpedance increased significantly. The ratio of increasing impedance can be up to 75% at frequencies lower than 10 Hz. And in the range from 1 kHz namic imaging showed that the changes in unilateral brain blood supply is accordant with the corresponding regions having a changing impedance.CONCLUSION: The changes in brain tissue impedance before and after ischemia can be imaged and it could be used as a variable for EIT imaging.