Water diffusion changes in Wallerian degeneration and their dependence on white matter architecture
Water diffusion changes in Wallerian degeneration and their dependence on white matter architecture
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DOI：
10.1006/nimg.2001.0765
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发表时间：
2001-06-01
期刊：
影响因子：
5.7
通讯作者：
Basser, P
中科院分区：
文献类型：
--
作者：
Pierpaoli, C;Barnett, A;Basser, P
本研究探讨水扩散的变化在沃勒变性。我们测量了一侧内囊后肢小的慢性腔隙性梗死患者下行运动通路的弥散张量（DT）和TB加权信号强度。我们比较了这些测量在健康和病变侧在不同水平的脑干尾侧的主要病变。我们发现，继发性白色变性是由扩散各向异性的大幅度减少，只有在纤维排列在孤立的束平行纤维的区域，如在大脑脚。在退化的途径穿过其他管道的地区，如在喙笔，矛盾的是几乎没有变化的扩散各向异性，但在测量的纤维取向的显着变化。在所有受影响的区域，弥散张量的迹线适度增加。这允许人们区分次级和初级光纤损耗，其中迹线的增加相当高。我们发现DT-MRI在检测Wallerian变性方面比TS加权MRI更敏感。在每个患者的受影响通路的整个轨迹上观察到显著的扩散异常。这一发现表明，映射退化的途径与DT-MRI非侵入性是可行的。然而，水扩散数据的解释是复杂的，需要先验信息的解剖结构和结构的途径正在调查。特别是，我们的研究表明，在纤维交叉的区域，现有的基于DT-MRI的纤维追踪算法可能会导致关于大脑连接的错误结论。
This study investigates water diffusion changes in Wallerian degeneration. We measured indices derived from the diffusion tensor (DT) and TB-weighted signal intensities in the descending motor pathways of patients with small chronic lacunar infarcts of the posterior limb of the internal capsule on one side. We compared these measurements in the healthy and lesioned sides at different levels in the brainstem caudal to the primary lesion. We found that secondary white matter degeneration is revealed by a large reduction in diffusion anisotropy only in regions where fibers are arranged in isolated bundles of parallel fibers, such as in the cerebral peduncle. In regions where the degenerated pathway crosses other tracts, such as in the rostral pens, paradoxically there is almost no change in diffusion anisotropy, but a significant change in the measured orientation of fibers. The trace of the diffusion tensor is moderately increased in all affected regions. This allows one to differentiate secondary and primary fiber loss where the increase in trace is considerably higher. We show that DT-MRI is more sensitive than TS-weighted MRI in detecting Wallerian degeneration. Significant diffusion abnormalities are observed over the entire trajectory of the affected pathway in each patient. This finding suggests that mapping degenerated pathways noninvasively with DT-MRI is feasible. However, the interpretation of water diffusion data is complex and requires a priori information about anatomy and architecture of the pathway under investigation. In particular, our study shows that in regions where fibers cross, existing DT-MRI-based fiber tractography algorithms may lead to erroneous conclusion about brain connectivity.