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首页> 外文学位 >Magnetic Resonance Gradient Echo Phase Imaging as a Means of Detecting Alterations in the Tissue Microarchitecture of the Human Corpus Callosum.
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Magnetic Resonance Gradient Echo Phase Imaging as a Means of Detecting Alterations in the Tissue Microarchitecture of the Human Corpus Callosum.

机译：磁共振梯度回波相位成像作为检测人类Corp体组织微体系结构变化的一种手段。

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摘要

Susceptibility sensitive MRI GRadient Echo (GRE) imaging produces two images, one of magnitude and one of phase. Most imaging studies ignore the phase image, despite the fact that the phase image has stronger contrast in some regions of the brain and therefore can show more detail than the magnitude image, primarily because there is no standard for acquisition, post-processing and display. Additionally, the source of this contrast is not fully understood. Therefore, a better understanding of phase images has the potential to elucidate structures that are currently not visible in the magnitude image, which could be useful in a variety of clinical applications.;In order to better understand the phase image, this dissertation first used computer simulation to model the expected phase signal in a white matter fiber tract. A two compartment susceptibility model was programmed using fiber tract specific information from histopathology studies on the human corpus callosum. This model was built on the discoveries of previous studies which indicated that bulk susceptibility may be the dominant source of phase contrast. The strength of this model was assessed by comparing predicted phase shifts for the computer-modeled corpus callosum fiber tracts with values taken from filtered phase images of a healthy subject brain. Additionally, T2* values were computed from the model and compared with measured values. To assess the effect of filtering on the phase, experiments using a homogeneous spherical phantom were performed. Finally, the ability of phase to classify mild Traumatic Brain Injury patients with persistent behavioral symptoms with no visible microhemorrhages, a population expected to have altered white matter microstructure, was explored using quantitative region-of-interest analysis.;This work shows that computer simulations using a simple two compartment susceptibility model that assumes a susceptibility of myelin to be equal to that measured for cholesterol can reasonably predict measured phase in healthy human subjects in the corpus callosum. In addition, these simulations predict statistically different phase for each of five region of the corpus callosum, which are also observed in the MRI susceptibility sensitive GRE phase images. Simulation also predicts T2* values within a factor of two of what is measured experimentally from the magnitude images. When images are compared using a consistent filtering method, measurable regional differences across the corpus callosum can be detected. Finally, this work shows that regional differences between two patient populations (mild Traumatic Brain Injury with persistent behavioral symptoms and healthy age-matched controls) can be detected in the absence of visible microhemorrhages, suggesting potential clinical application for susceptibility sensitive phase imaging.
机译：磁化率敏感的MRI梯度回波（GRE）成像可产生两幅图像，一幅为幅相，另一幅为相位。尽管相位图像在大脑的某些区域具有更强的对比度，因此可以比幅度图像显示更多的细节，但大多数成像研究都忽略了相位图像，这主要是因为没有采集，后处理和显示的标准。此外，这种对比的来源还不完全清楚。因此，更好地理解相位图像有可能阐明当前在幅值图像中不可见的结构，这可能在多种临床应用中很有用。为了更好地理解相位图像，本论文首先使用了计算机模拟以对白质纤维束中的预期相位信号建模。使用来自人call体组织病理学研究的纤维束特定信息，对两室敏感性模型进行编程。该模型建立在先前研究的发现之上，该研究表明，整体磁化率可能是相衬的主要来源。通过将计算机建模的call体纤维束的预测相移与从健康受试者大脑的已过滤相位图像中获取的值进行比较，可以评估该模型的强度。此外，从模型计算出T2 *值，并将其与测量值进行比较。为了评估过滤对相位的影响，进行了使用均质球形体模的实验。最后，使用定量的感兴趣区域分析，探索了对具有持续行为症状，无明显微出血，预计白质微观结构已改变的人群的轻度创伤性脑损伤患者进行阶段分类的能力。使用简单的两室敏感性模型，假设髓磷脂的敏感性等于测得的胆固醇，可以合理地预测call体中健康人类受试者的测量阶段。此外，这些模拟为call体的五个区域中的每个区域预测了统计上不同的相位，这在MRI敏感性GRE相位图像中也可以观察到。仿真还可以预测，T2 *值应在从幅值图像中实验测得的值的两倍之内。使用一致的过滤方法比较图像时，可以检测到整个call体上可测量的区域差异。最后，这项工作表明，在没有可见的微出血的情况下，可以检测到两个患者群体之间的区域差异（轻度创伤性脑损伤，伴有持续的行为症状和健康的年龄匹配的对照），这提示了敏感性敏感性相成像的潜在临床应用。

著录项

  • 作者

    Schreiber, Sharon Kristen.;

  • 作者单位

    The Ohio State University.;

  • 授予单位 The Ohio State University.;
  • 学科 Engineering Biomedical.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 240 p.
  • 总页数 240
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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