Kimel Family Translational Imaging-Genetics Laboratory, Campbell Family Mental Health Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Research Imaging Centre, Campbell Family Mental Health Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada.
Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada.
Biol Psychiatry. 2017 Nov 15;82(10):726-736. doi: 10.1016/j.biopsych.2016.12.005. Epub 2016 Dec 8.
Postmortem studies have demonstrated considerable dendritic pathologies among persons with schizophrenia and to some extent among those with bipolar I disorder. Modeling gray matter (GM) microstructural properties is now possible with a recently proposed diffusion-weighted magnetic resonance imaging modeling technique: neurite orientation dispersion and density imaging. This technique may bridge the gap between neuroimaging and histopathological findings.
We performed an extended series of multishell diffusion-weighted imaging and other structural imaging series using 3T magnetic resonance imaging. Participants scanned included individuals with schizophrenia (n = 36), bipolar I disorder (n = 29), and healthy controls (n = 35). GM-based spatial statistics was used to compare neurite orientation dispersion and density imaging-driven microstructural measures (orientation dispersion index and neurite density index [NDI]) among groups and to assess their relationship with neurocognitive performance. We also investigated the accuracy of these measures in the prediction of group membership, and whether combining them with cortical thickness and white matter fractional anisotropy further improved accuracy.
The GM-NDI was significantly lower in temporal pole, anterior parahippocampal gyrus, and hippocampus of the schizophrenia patients than the healthy controls. The GM-NDI of patients with bipolar I disorder did not differ significantly from either schizophrenia patients or healthy controls, and it was intermediate between the two groups in the post hoc analysis. Regardless of diagnosis, higher performance in spatial working memory was significantly associated with higher GM-NDI mainly in the frontotemporal areas. The addition of GM-NDI to cortical thickness resulted in higher accuracy to predict group membership.
GM-NDI captures brain differences in the major psychoses that are not accessible with other structural magnetic resonance imaging methods. Given the strong association of GM-NDI with disease state and neurocognitive performance, its potential utility for biological subtyping should be further explored.
尸检研究表明，精神分裂症患者以及在某种程度上双相情感障碍 I 型患者存在大量树突状病理学。目前，一种新提出的扩散加权磁共振成像建模技术——神经丝取向分散和密度成像——可以对灰质（GM）微观结构特性进行建模。该技术可能在神经影像学和组织病理学发现之间架起桥梁。
我们使用 3T 磁共振成像进行了一系列扩展的多壳层扩散加权成像和其他结构成像序列。扫描的参与者包括精神分裂症患者（n=36）、双相情感障碍 I 型患者（n=29）和健康对照组（n=35）。我们使用基于 GM 的空间统计学来比较组间神经丝取向分散和密度成像驱动的微观结构测量值（取向分散指数和神经丝密度指数[NDI]），并评估它们与神经认知表现的关系。我们还研究了这些测量值在预测群体归属中的准确性，以及将它们与皮质厚度和白质各向异性分数结合是否能进一步提高准确性。
与健康对照组相比，精神分裂症患者的颞极、前海马旁回和海马 GM-NDI 显著降低。双相情感障碍 I 型患者的 GM-NDI 与精神分裂症患者或健康对照组无显著差异，在后测分析中，其处于两组之间的中间位置。无论诊断如何，空间工作记忆的较高表现与 GM-NDI 的升高显著相关，主要与额颞区有关。将 GM-NDI 添加到皮质厚度中可以提高预测群体归属的准确性。
GM-NDI 可以捕捉到主要精神疾病的大脑差异，而其他结构磁共振成像方法则无法捕捉到这些差异。鉴于 GM-NDI 与疾病状态和神经认知表现的强烈关联，应进一步探索其用于生物学亚型的潜在效用。
