Purpose Glaucoma is a disorder that involves visual field loss caused by retinal ganglion cell damage. Previous diffusion magnetic resonance imaging (dMRI) studies have demonstrated that retinal ganglion cell damage affects tissues in the optic tract (OT) and optic radiation (OR). However, because previous studies have used a simple diffusion tensor model to analyze dMRI data, the microstructural interpretation of white matter tissue changes remains uncertain. In this study, we used a multi-contrast MRI approach to further clarify the type of microstructural damage that occurs in glaucoma patients. Methods We collected multi-shell dMRI data from 17 glaucoma patients and 30 controls using 3T MRI. Using the dMRI data, we estimated three types of tissue property metrics: intracellular volume fraction (ICVF), orientation dispersion index (ODI), and isotropic volume fraction (IsoV). Quantitative T1 (qT1) data, which may be relatively specific to myelin, were collected from all subjects. Results In the OT, all four metrics showed significant differences between the glaucoma and control groups. In the OR, only the ICVF showed significant between-group differences. ICVF was significantly correlated with qT1 in the OR of glaucoma patients, although qT1 did not show any abnormality at the group level. Conclusions Our results suggest that at the group level, tissue changes in the glaucoma patients' OR might be explained by axonal damage, which is reflected in the intracellular diffusion signals, rather than myelin damage. The significant correlation between ICVF and qT1 suggests that myelin damage might also occur in a smaller number of severe cases.

中文翻译：

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青光眼患者视觉白质通路的多对比磁共振成像

目的 青光眼是一种由视网膜神经节细胞损伤引起的视野丧失的疾病。先前的扩散磁共振成像 (dMRI) 研究表明，视网膜神经节细胞损伤会影响视束 (OT) 和视辐射 (OR) 中的组织。然而，由于以前的研究使用简单的扩散张量模型来分析 dMRI 数据，白质组织变化的微观结构解释仍然不确定。在这项研究中，我们使用多对比 MRI 方法来进一步阐明青光眼患者发生的微观结构损伤的类型。方法 我们使用 3T MRI 从 17 名青光眼患者和 30 名对照中收集了多壳 dMRI 数据。使用 dMRI 数据，我们估计了三种类型的组织特性指标：细胞内体积分数 (ICVF)、取向分散指数 (ODI) 和各向同性体积分数 (IsoV)。从所有受试者收集了定量 T1 (qT1) 数据，这些数据可能对髓磷脂具有相对特异性。结果 在 OT 中，所有四个指标都显示青光眼组和对照组之间存在显着差异。在 OR 中，只有 ICVF 显示出显着的组间差异。ICVF 与青光眼患者 OR 中的 qT1 显着相关，尽管 qT1 在组水平上没有显示任何异常。 结论 我们的结果表明，在组水平上，青光眼患者 OR 的组织变化可能是由轴突损伤来解释的，轴突损伤反映在细胞内扩散信号中，而不是髓鞘损伤。ICVF 和 qT1 之间的显着相关性表明髓鞘损伤也可能发生在少数严重病例中。