面向复杂脑神经纤维结构重建的处理方法研究

发布时间：2018-03-07 02:15

  本文选题：扩散张量成像(DTI)　切入点：Q-Ball成像(QBI)　出处：《天津大学》2012年硕士论文　论文类型：学位论文

【摘要】：本论文结合国家自然科学基金项目,对交叉、弯曲、分叉等复杂脑白质纤维重建方法进行研究。论述了常见的扩散张量成像(DTI)、Q-Ball成像(QBI)和四阶张量成像(DT4)的原理、计算过程及主要的优缺点。主要研究内容如下: 首先,针对多梯度DTI,运用多元线性回归的方法求解其扩散张量矩阵;并利用梯度编码矩阵的条件数和各向异性标准偏差作为定量评价采样方案和成像精度的标准;然后用20梯度方向方案与传统的6方向和12方向的方案进行对比,以评价梯度方向数对成像质量的影响。 其次,针对QBI来重建方向分布函数的方法,研究了其重建的Funk-Radon变换基本理论、高斯径向基函数插值的方法和在MATLAB中进行曲面重建的方法;并讨论了实验参数如视场大小(FOV)、b值等对图像信噪比、空间分辨率和扫描时间的影响;最后对结构较复杂处如视辐射线、前额皮质等用QBI成像以观察成像效果。 再次,针对QBI的缺陷,研究了DT4重建的基本原理和计算过程以及参数如角度重建误差、规范化各向异性等的表达形式;又引进计算机仿真的方法定量地评价不同噪声值和采样梯度方向数对重建角度误差和规范化张量标准偏差等的影响;然后从算法、实验和成像效果三方面对DTI、QBI、和DT4成像进行对比,以证明DT4在未来临床应用中更有优势和潜力。 本文完成了DTI、QBI和DT4成像的可视化研究,将可视化的结果与人类大脑的解剖结构进行比较,验证了研究结果的正确性,为以后的脑神经纤维追踪和临床应用奠定了理论基础。
[Abstract]:In this paper, the reconstruction methods of complex white matter fibers, such as crossover, bending and bifurcation, are studied in conjunction with the project of National Natural Science Foundation of China. The principles of diffusion imaging Zhang Liang's Q-Ball imaging QBI4 and fourth order Zhang Liang imaging DT4 are discussed. The main research contents are as follows:. Firstly, the multivariate linear regression method is used to solve the diffusion Zhang Liang matrix for multi-gradient DTI, and the condition number of gradient coding matrix and anisotropic standard deviation are used as the criteria for quantitative evaluation of sampling scheme and imaging accuracy. Then, the 20 gradient direction scheme is compared with the traditional six and twelve directions scheme to evaluate the influence of gradient direction number on the imaging quality. Secondly, the basic theory of Funk-Radon transform, the interpolation method of Gao Si radial basis function and the method of surface reconstruction in MATLAB are studied according to the method of QBI to reconstruct the directional distribution function. The effects of experimental parameters such as field of view (FOV) value on image signal-to-noise ratio (SNR), spatial resolution and scanning time are discussed. Finally, QBI imaging is used to observe the imaging effect for complex structures such as apparent radiation lines and prefrontal cortex. Thirdly, aiming at the defects of QBI, the basic principle and calculation process of DT4 reconstruction and the expressions of parameters such as angle reconstruction error and normalized anisotropy are studied. Computer simulation is introduced to quantitatively evaluate the effects of different noise values and sampling gradient directions on the reconstruction angle error and standardized Zhang Liang standard deviation. In order to prove that DT4 has more advantages and potential in clinical application in the future, the QBI and DT4 imaging are compared in three aspects of experimental and imaging effects. The visualization of DTI QBI and DT4 imaging has been completed in this paper. The results of visualization are compared with the anatomical structure of human brain, and the correctness of the results is verified, which lays a theoretical foundation for the follow-up and clinical application of brain nerve fibers.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TP391.41;R311

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