A framework for voxel-based morphometric analysis of the optic radiation using diffusion tensor imaging in glaucoma
A framework for voxel-based morphometric analysis of the optic radiation using diffusion tensor imaging in glaucoma
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DOI：
10.1016/j.mri.2011.02.034
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发表时间：
2011-10-01
影响因子：
2.5
通讯作者：
Michelson, Georg
中科院分区：
文献类型：
--
作者：
El-Rafei, Ahmed;Engelhorn, Tobias;Michelson, Georg
青光眼是一种影响整个视觉系统的视神经病变。青光眼的发病机制和病因目前尚无定论。扩散张量成像(DTI)已被用于分析视神经和视神经辐射，显示与青光眼相关的整体纤维异常。然而，光辐射的复杂结构和DTI的局限性使得青光眼效应的定位成为一项困难的任务。这项工作的目的是建立一个框架，以确定由青光眼引起的局部光辐射变化的DTI。所提出的系统利用半自动算法来产生光学辐射的有效识别。利用基于形状的非刚性配准将分割后的光辐射变换到统一的空间。利用配准得到的形变场，将扩散张量衍生参数的映射变换到统一空间。这使得统计体素分析能够产生显著的异常图。该系统被应用于13名青光眼患者和10名正常对照组。这些组是年龄匹配的，以消除年龄对分析的影响。研究了与扩散相关的参数(轴向、径向和平均扩散系数)和各向异性指数(分数各向异性)。各向异性分析表明，与对照组相比，青光眼患者的大部分显著体素表现出降低的分数各向异性。此外，有意义的区域主要分布在视神经辐射的中部(参照前后方位)。青光眼患者的径向弥散系数和平均弥散系数显著增加，体素主要集中在右眼辐射的近端。建议的分析提供了一个框架，以捕捉青光眼引起的局部光学辐射的显著变化。初步分析认为，青光眼视神经辐射可能为局限性白质变性。该框架有助于进一步研究和了解青光眼(C)2011 Elsevier Inc.的病理生理学。保留所有权利。
Glaucoma is an optic neuropathy affecting the entire visual system. The understanding of the glaucoma mechanism and causes remains unresolved. Diffusion tensor imaging (DTI) has been used to analyze the optic nerve and optic radiation showing global fiber abnormalities associated with glaucoma. Nevertheless, the complex structure of the optic radiation and the limitations of DTI make the localization of the glaucoma effect a difficult task. The aim of this work is to establish a framework for the determination of the local changes of the optic radiation due to glaucoma using DTI. The proposed system utilizes a semiautomated algorithm to produce an efficient identification of the optic radiation. Segmented optic radiations are transformed to a unified space using shape-based nonrigid registration. Using the deformation fields that resulted from the registration, the maps of the diffusion tensor-derived parameters are transformed to the unified space. This allows for statistical voxel-wise analysis to produce significant abnormality maps. The proposed system is applied to a group of 13 glaucoma patients and a normal control group of 10 subjects. The groups are age matched to eliminate the age effect on the analysis. Diffusion-related parameters (axial, radial and mean diffusivities) and an anisotropy index (fractional anisotropy) are studied. The anisotropy analysis indicates that the majority of the significant voxels show decreased fractional anisotropy in the glaucoma patients compared with the control group. In addition, the significant regions are mainly distributed in the middle (in reference to anterior posterior orientation) of the optic radiation. Glaucoma subjects have increased radial diffusivity and mean diffusivity significant voxels with a main concentration in the proximal part of the right optic radiation. The proposed analysis provides a framework to capture the significant local changes of the optic radiation due to glaucoma. The preliminary analysis suggests that the glaucomatous optic radiation may suffer from localized white matter degeneration. The framework facilitates further studies and understanding of the pathophysiology of glaucoma (C) 2011 Elsevier Inc. All rights reserved.