Atkinson-Clement Cyril, Pinto Serge, Eusebio Alexandre, Coulon Olivier
Aix Marseille Univ, CNRS, LPL, Aix-en-Provence, France.
Brain and Language Research Institute, Aix Marseille Univ, Aix-en-Provence, France.
Neuroimage Clin. 2017 Jul 15;16:98-110. doi: 10.1016/j.nicl.2017.07.011. eCollection 2017.
Neuroimaging studies help us better understand the pathophysiology and symptoms of Parkinson's disease (PD). In several of these studies, diffusion tensor imaging (DTI) was used to investigate structural changes in cerebral tissue. Although data have been provided as regards to specific brain areas, a whole brain meta-analysis is still missing.
We compiled 39 studies in this meta-analysis: 14 used fractional anisotropy (FA), 1 used mean diffusivity (MD), and 24 used both indicators. These studies comprised 1855 individuals, 1087 with PD and 768 healthy controls. Regions of interest were classified anatomically (subcortical structures; white matter; cortical areas; cerebellum). Our statistical analysis considered the disease effect size (D) as the main variable; the heterogeneity index (I) and Pearson's correlations between the D and co-variables (demographic, clinical and MRI parameters) were also calculated.
Our results showed that FA-D and MD-D were able to distinguish between patients and healthy controls. Significant differences, indicating degenerations, were observed within the substantia nigra, the corpus callosum, and the cingulate and temporal cortices. Moreover, some findings (particularly in the corticospinal tract) suggested opposite brain changes associated with PD. In addition, our results demonstrated that MD-D was particularly sensitive to clinical and MRI parameters, such as the number of DTI directions and the echo time within white matter.
Despite some limitations, DTI appears as a sensitive method to study PD pathophysiology and severity. The association of DTI with other MRI methods should also be considered and could benefit the study of brain degenerations in PD.
神经影像学研究有助于我们更好地理解帕金森病（PD）的病理生理学和症状。在其中一些研究中，扩散张量成像（DTI）被用于研究脑组织的结构变化。尽管已经提供了关于特定脑区的数据，但全脑荟萃分析仍然缺失。
我们在这项荟萃分析中汇总了39项研究：14项使用了分数各向异性（FA），1项使用了平均扩散率（MD），24项同时使用了这两种指标。这些研究包括1855名个体，其中1087名患有PD，768名是健康对照。感兴趣区域按解剖学分类（皮层下结构；白质；皮层区域；小脑）。我们的统计分析将疾病效应大小（D）作为主要变量；还计算了异质性指数（I）以及D与协变量（人口统计学、临床和MRI参数）之间的Pearson相关性。
我们的结果表明，FA-D和MD-D能够区分患者和健康对照。在黑质、胼胝体以及扣带回和颞叶皮层中观察到了表明退化的显著差异。此外,一些发现（特别是在皮质脊髓束中）表明与PD相关的脑变化相反。此外，我们的结果表明，MD-D对临床和MRI参数特别敏感，如DTI方向的数量和白质内的回波时间。
尽管存在一些局限性，但DTI似乎是研究PD病理生理学和严重程度的一种敏感方法。还应考虑DTI与其他MRI方法的关联，这可能有益于PD脑退化的研究。
