急性脑创伤脑组织介电特性

Dielectric properties of brain tissues following acute brain injury

目的:研究家兔急性脑创伤脑组织介电特性(相对介电常数和电导率),为微波脑损伤检测技术提供依据。方法:实验组10只家兔以0.8 MPa压强撞击家兔颅顶部,建立急性脑创伤模型。在致伤部位开颅骨窗,采用开端同轴探针法在500 MHz~3 GHz频段范围内对致伤后30、45、60、75、90、105 min脑创伤部位脑组织进行介电特性测量。对照组10只家兔不撞击,其他步骤与实验组相同。结果:相同时间相同频率下,急性脑创伤脑组织的相对介电常数和电导率大于正常家兔脑组织(P<0.01)。在相同时间,急性脑创伤脑组织和正常家兔脑组织的相对介电常数随频率的增加而减小,电导率随频率的增加而增大。在相同频率,急性脑创伤脑组织相对介电常数和电导率随时间的增加而增大,而正常家兔脑组织的相对介电常数和电导率随时间的增加而保持相对稳定。结论:急性脑创伤后脑组织的介电特性发生明显改变,表明基于组织电特性的微波检测技术应用于脑创伤检测监测具有可行性。

Objective To study the dielectric properties(permittivity and conductivity)of the brain tissues in rabbits with acute brain injury,thereby providing a basis for brain injury detection using microwave tomography.Methods The top of the skull of 10 rabbits in experimental group was hit with a pressure of 0.8 MPa to establish the acute brain injury model.At the craniotomy window at the site of injury,the dielectric properties of the brain tissues were measured using the open-ended coaxial probe in the frequency ranging from 500MHz to 3 GHz at 30,45,60,75,90 and 105 min after injury.The 10 rabbits in control group were given the same treatment as that in experimental group except hit on the skull.Results At the same time and frequency,the permittivity and conductivity of brain tissues following acute brain injury were higher than those of normal rabbit brain tissues(P<0.01).At the same time,the permittivity of brain tissues following acute brain injury and normal rabbit brain tissues decreased with increasing frequency,while the conductivity increased with increasing frequency.At the same frequency,the permittivity and conductivity of brain tissues following acute brain injury increased with time,while the permittivity and conductivity of normal rabbit brain tissues remained relatively stable.Conclusion The dielectric properties of brain tissue following acute brain injury changed significantly,indicating that the microwave tomography based on tissue electrical properties is feasible for brain injury detection.