Can spherical deconvolution provide more information than fiber orientations? Hindrance modulated orientational anisotropy, a true-tract specific index to characterize white matter diffusion
Can spherical deconvolution provide more information than fiber orientations? Hindrance modulated orientational anisotropy, a true-tract specific index to characterize white matter diffusion
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DOI：
10.1002/hbm.22080
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发表时间：
2013-10-01
影响因子：
4.8
通讯作者：
Catani, Marco
中科院分区：
文献类型：
--
作者：
Dell'Acqua, Flavio;Simmons, Andrew;Catani, Marco
扩散张量成像（DTI）方法被广泛用于重建白质轨迹，并利用每个脑体素的平均扩散特性来量化组织变化。球面反褶积（SD）方法的发展是为了克服扩散张量模型在分辨交叉纤维方面的局限性，并改善束束成像的重建。然而，使用SD方法获得白质完整性的定量指标尚未得到广泛的探索。在这项研究中，我们证明了阻碍调制取向各向异性（HMOA）指数，定义为纤维取向分布的每个叶的绝对振幅，可以作为一个紧凑的度量来表征具有复杂组织的白质区域中沿每个纤维取向的扩散特性。我们证明HMOA对纤维扩散率的变化（如髓鞘形成过程或轴突损失）和白质微观结构组织的差异（如轴突直径和纤维弥散）高度敏感。通过模拟描述在正常大脑发育和疾病中观察到的弥散性变化，我们观察到HMOA能够识别传统DTI指数无法检测到的白质变化。我们还表明，HMOA指数可以作为体内数据的有效阈值，以改善神经束造影重建，并更好地绘制大脑内白质的复杂性。总之，HMOA代表了一个真正的通道特异性和敏感性指数，并提供了白质扩散特性的紧凑表征，具有在正常和临床人群中广泛应用的潜力。[j] .中国生物医学工程学报，2013。(c) 2012 Wiley期刊有限公司
Diffusion tensor imaging (DTI) methods are widely used to reconstruct white matter trajectories and to quantify tissue changes using the average diffusion properties of each brain voxel. Spherical deconvolution (SD) methods have been developed to overcome the limitations of the diffusion tensor model in resolving crossing fibers and to improve tractography reconstructions. However, the use of SD methods to obtain quantitative indices of white matter integrity has not been extensively explored. In this study, we show that the hindrance modulated orientational anisotropy (HMOA) index, defined as the absolute amplitude of each lobe of the fiber orientation distribution, can be used as a compact measure to characterize the diffusion properties along each fiber orientation in white matter regions with complex organization. We demonstrate that the HMOA is highly sensitive to changes in fiber diffusivity (e.g., myelination processes or axonal loss) and to differences in the microstructural organization of white matter like axonal diameter and fiber dispersion. Using simulations to describe diffusivity changes observed in normal brain development and disorders, we observed that the HMOA is able to identify white matter changes that are not detectable with conventional DTI indices. We also show that the HMOA index can be used as an effective threshold for in vivo data to improve tractography reconstructions and to better map white matter complexity inside the brain. In conclusion, the HMOA represents a true tract-specific and sensitive index and provides a compact characterization of white matter diffusion properties with potential for widespread application in normal and clinical populations. Hum Brain Mapp 34:2464-2483, 2013. (c) 2012 Wiley Periodicals, Inc.