Fixel-Based Analysis of Visual Pathway White Matter in Primary Open-Angle Glaucoma
Fixel-Based Analysis of Visual Pathway White Matter in Primary Open-Angle Glaucoma
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DOI：
10.1167/iovs.19-27447
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发表时间：
2019-09-01
影响因子：
4.4
通讯作者：
Cornelissen, Frans W.
中科院分区：
文献类型：
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作者：
Haykal, Shereif;Curcic-Blake, Branislava;Cornelissen, Frans W.
目的.原发性开角型青光眼（primary open-angle glaucoma，POAG）视路的白色物质（White matter，WM）变性已被广泛报道，但其确切的病理生理机制尚不清楚。迄今为止，仅使用扩散张量成像（DTI）专门研究了脑白质退化。然而，DTI测量缺乏直接的生物学解释，并且该方法本身受到多种技术限制。基于固定的分析（FBA）是一种新的框架，用于研究WM变性，克服DTI的技术局限性，并提供生物学意义的指标。FBA测量纤维密度（FD），代表早期的微观结构变化，和纤维束横截面（FC），代表后期的宏观结构变化。在本研究中，我们使用FBA来研究POAG中膝状体前视束（OTs）和膝状体后视放射（ORs）的昏迷性变性。这是一项横断面病例对照研究，包括12例POAG患者和16例对照。获取多层扩散加权图像。FBA用于产生群体模板，并且概率纤维束成像用于在模板空间中跟踪OT和OR。最后比较两组间感兴趣束的FD和FC。与对照组相比，FD和FC患者的OT值显著降低（经家庭误差校正P < 0.05），而FD患者的OR值显著降低，而FC患者的OR值无显著性差异。FBA提供了敏感的措施，以评估青光眼WM的变化。我们的研究结果表明，青光眼患者的OT表现出更先进的WM变性的迹象相比，OR。这可能意味着顺行跨突触传播是导致视觉通路沿着扩散的主要原因。
PURPOSE. White matter (WM) degeneration of the visual pathways in primary open-angle glaucoma (POAG) is well documented, but its exact pathophysiology remains unclear. To date, glaucomatous WM degeneration has been exclusively studied using diffusion tensor imaging (DTI) only. However, DTI measures lack direct biological interpretation, and the approach itself suffers from multiple technical limitations. Fixel-based analysis (FBA) is a novel framework for studying WM degeneration, overcoming DTI's technical limitations and providing biologically meaningful metrics. FBA measures fiber density (FD), representing early microstructural changes, and fiber-bundle cross section (FC), representing late macrostructural changes. In this study, we use FBA to study glaucomatous degeneration of the pregeniculate optic tracts (OTs) and postgeniculate optic radiation (ORs) in POAG.METHODS. This was a cross-sectional case-control study with 12 POAG patients and 16 controls. Multi-shell diffusion-weighted images were acquired. FBA was used to produce a population template, and probabilistic tractography was used to track the OTs and ORs in template space. Finally, FD and FC of the tracts of interest were compared between the two groups.RESULTS. Compared with the controls, the OTs of the patients exhibited a significant (familywise error corrected P < 0.05) decrease in FD and FC, whereas their ORs exhibited a significant decrease in FD but not in FC.CONCLUSIONS. FBA provides sensitive measures to assess WM changes in glaucoma. Our findings suggest that the OTs of glaucoma patients exhibit signs of more advanced WM degeneration compared with the ORs. This potentially implicates anterograde trans-synaptic propagation as the primary cause of glaucomatous spread along the visual pathways.