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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0.1Hz～1MHz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10Hz以下脑阻抗变化率可达75%,在1kHz～1MHz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。
Background: Electrical impedance tomography (CT) technique is to apply harmless electrical signals to human body surface and to measure its response on the body surface. The distribution image of the internal electrical impedance or its variation is obtained by reconstruction algorithm. Compared with the existing CT, MRI and other technologies, electrical impedance tomography has the advantages of real-time, low cost, easy continuous monitoring and functional imaging. OBJECTIVE: To characterize the electrical impedance characteristics of rabbit brain tissue before and after ischemia, and to evaluate the potential of electrical impedance tomography imaging of brain function changes by performing electrical impedance tomography on ischemic brain tissue. Design: Single sample experiment. Unit: PLA Fourth Military Medical Biomedical Engineering Department of Medical Electronics Engineering. MATERIALS: Experiments were performed at the Electrical Impedance Tomography Laboratory, Department of Medical Electronics Engineering, Department of Biomedical Engineering, Fourth Military Medical University, People’s Liberation Army from August to September 09. Ten adult healthy rabbits were selected for experiment. Methods: The model of cerebral ischemia was made by carotid artery ligation. The electrical impedance characteristics of brain tissue before and after ischemia were measured in vivo. Electrical impedance tomography system was used to image the change of blood supply in unilateral brain. MAIN OUTCOME MEASURES: ① The impedance characteristics of the brain tissue before and after ischemia in 0.1Hz ~ 1MHz frequency range. ② unilateral brain tissue changes in electrical impedance tomography results. Results: One rabbit was drilled through the dura and the results of nine rabbits were analyzed. (1) After ischemic brain injury, the brain impedance increased obviously. The rate of change of brain impedance was up to 75% under 10Hz. The rate of change of brain impedance was about 15% in the frequency range from 1kHz to 1MHz and was stable. ② preliminary dynamic imaging results show that the side of the brain tissue changes in blood supply and its resistivity changes in the same location. Conclusion: The rate of change of impedance of brain tissue before and after ischemia can meet the requirement of imaging and can be used as an imaging variable.