基于扩散张量成像技术统一计算脑组织各向异性电导率的关键技术研究

It is very important to obtain high-resolution conductivity distribution of brain tissue non-invasively for the research of brain function and brain disease. This project proposed the unified computing model based on diffusion tensor imaging with higher resolution and signal-to-noise ratio. But the traditional conductivity imaging methods are difficult to get the goal..The physical structure of internal organization of brain (gray matter, cerebrospinal fluid, white matter) is quite complex, and it's conductivity distribution is inhomogeneous and anisotropic. This project put forward with a new method to calculate the anisotropic conductivity of brain inner tissue. First the equation of Stokes-Einstein and Nernst-Einstein were used to convert diffusion tensor to conductivity tensor, and then the conversion coefficient was calculated according to the ratio of the radius of the conductive particle to water molecule and the particle concentration in the brain liquid. This method could not only avoid direct consideration of the complex structure of brain tissue and improve imaging accuracy, but also could effectively overcome the influence of volume effect on the conductivity calculations. Finally the new method would be tested on the cylinder model containing NaCl solution and 30um-D glass fiber bundles..The project will find a new way to get high-resolution anisotropic conductivity imaging of brain tissue.

无创获取脑组织高分辨率电导率分布对脑功能研究与脑疾病临床诊断具有重要科学意义。本项目提出基于扩散张量成像技术脑组织电导率统一计算新模型，可解决传统电导率成像方法难以解决的各向异性问题，且具有较高的分辨率和信噪比。.脑内部组织（灰质、脑脊液、白质）生理结构复杂，其电导率分布具有非均值性与各向异性的特点。本项目初步实现基于水分子扩散张量计算电导率的新方法，采用Stokes-Einstein与Nernst-Einstein方程来完成扩散张量到电导率张量的转化，根据脑液体中导电粒子浓度与粒子－水分子半径比两因素来计算张量转化系数。该方法不仅避免直接考虑脑组织复杂生理结构对电导率成像的影响，提高成像精度；而且能够有效克服扩散张量成像中容积效应对电导率计算结果的影响。最后将在圆柱体氯化钠溶液30um直径玻璃纤维束模型中进行验证。.项目研究成果将为脑组织高分辨率各向异性电导率成像开辟一条新途径。

扩散张量成像是一种无损伤成像新技术，具有很高的空间分辨率。基于扩散张量成像的脑组织电导率计算是近几年来的一项重要研究课题。脑内部组织（灰质、脑脊液、白质）生理结构复杂，其电导率分布具有非均值性与各向异性的特点。本项目提出了基于扩散张量成像技术计算脑组织电导率的新方法，可解决传统方法难以高精度测量各向异性电导率的问题。.本项目实现了基于扩散张量计算电导率的新方法，采用Stokes-Einstein与 Nernst-Einstein方程来完成扩散张量到电导率张量的转化，根据脑液体中导电粒子浓度与粒子/水分子半径比来计算转化系数。经过计算模型验证，脑组织水分子扩散张量与其电导率张量之间存在强线性关系。根据该方法进行计算，得到脑脊液扩散张量到电导率张量的转换系数为1.0061，脑灰质/白质扩散张量到电导率张量的转换系数为0.9007。.在脑组织电导率成像领域，该项目提出的新方法为无创获取脑组织高分辨率各向异性电导率开辟了一条新途径。