家兔脑组织复电阻抗频率特性及其等效电路模型

THE IN VITRO MEASUREMENT OF THE RABBIT BRAIN COMPLEX IMPEDANCE FREQUENCY RESPONSE AND THE EQUIVALENT CIRCUIT MODEL

目的 :研究大脑组织的复电阻抗频率特性 ,分析缺血对大脑组织复电阻抗频率特性的影响 ,构建大脑组织的复电阻抗等效电路模型。方法 :利用频响分析仪 (12 5 5B ,英国Solartron公司 ) ,二电极测量法 ,对 12只家兔正常、缺血状态大脑组织复电阻抗频率特性进行离体测量 ,脑缺血方法采用的是颈总动脉结扎法 ,等效电路模型分析采用阻抗分析软件 (Zplot 2 .1,英国Solartron公司 ) ,还经过脑组织病理学常规染色 (HE染色 )对脑缺血进行了验证。结果 :在缺血脑损伤发生后 ,脑组织复电阻抗实部、虚部均明显增大 ,电阻率变化率受频率影响较小 ,但脑组织复电阻抗虚部频率特性未呈现出单峰走势 ,经软件分析得到了脑组织的复电阻抗等效电路模型。讨论 :脑组织复电阻抗实部、虚部和电阻率变化率均可以作为成像变量 ;其复电阻抗等效电路模型显示整体脑组织的等效电路模型构成比较复杂 ,并非传统的生物组织三元件等效电路模型 。

AIM: To study the effect of ischemia on complex electrical impedance characteristics of brain, and reconstruct the equivalent electrical model. METHODS: The in vitro measurement of rabbit brain tissue complex impedance was made under both normal and ischemc conditions by using four-electrode measurement methods in the frequency range from 0.1 Hz to 1 MHz. RESULTS: The impedance and complex impedance frequency response curves of rabbit brain in vitro were obtained and showed a significant difference (P < 0.001) when the ischemia occurred, and the magnitude of real part and imaginary part increased remarkably. The curves of imaginary part frequency response increased monotonously, not presented as a single peak as other bio-tissues did. The equivalent circuit model was obtained by using impedance analysis software. CONCLUSION: Both real and imaginary part of brain tissue complex impedance could be used as imaging variables. The traditional 'three-component' model can not be used to reconstruct the equivalent electrical model of whole brain tissue. The circuit model shows that the brain tissue is complex. It is necessary to measure different components of the brain in the further study.