Florey Institute of Neuroscience and Mental Health, Melbourne, Victoria, Australia; Department of Neuroimaging, Institute of Psychiatry, Psychology, and Neuroscience (IoPPN), King's College London, UK.
Florey Institute of Neuroscience and Mental Health, Melbourne, Victoria, Australia; Melbourne School of Psychological Sciences, University of Melbourne, Victoria, Australia.
Neuroimage. 2020 Sep;218:116869. doi: 10.1016/j.neuroimage.2020.116869. Epub 2020 Apr 22.
White matter hyperintensities (WMHs) are frequently observed on brain scans of older individuals and are associated with cognitive impairment and vascular brain burden. Recent studies have shown that WMHs may only represent an extreme end of a diffuse pathological spectrum of white matter (WM) degeneration. The present study investigated the microstructural characteristics of WMHs using an advanced diffusion MRI modelling approach known as Single-Shell 3-Tissue Constrained Spherical Deconvolution (SS3T-CSD), which provides information on different tissue compartments within each voxel. The SS3T-CSD method may provide complementary information in the interpretation of pathological tissue through the tissue-specific microstructural compositions of WMHs. Data were obtained from stroke patients enrolled in the Cognition and Neocortical Volume After Stroke (CANVAS) study, a study examining brain volume and cognition after stroke. WMHs were segmented using an automated method, based on fluid attenuated inversion recovery (FLAIR) images. Automated tissue segmentation was used to identify normal-appearing white matter (NAWM). WMHs were classified into juxtaventricular, periventricular and deep lesions, based on their distance from the ventricles (3-10 mm). We aimed to compare in stroke participants the microstructural composition of the different lesion classes of WMHs and compositions of NAWM to assess the in-vivo heterogeneity of these lesions. Results showed that the 3-tissue composition significantly differed between WMHs classes and NAWM. Specifically, the 3-tissue compositions for juxtaventricular and periventricular WMHs both exhibited a relatively greater fluid-like (free water) content, which is compatible with a presence of interstitial fluid accumulation, when compared to deep WMHs. These findings provide evidence of microstructural heterogeneity of WMHs in-vivo and may support new insights for understanding the role of WMH development in vascular neurodegeneration.
脑白质高信号（WMHs）在老年人群的脑部扫描中经常被观察到，与认知障碍和血管性脑负担有关。最近的研究表明，WMHs 可能仅代表弥漫性白质（WM）变性病理谱的一个极端。本研究使用一种称为单壳 3 组织约束球分解（SS3T-CSD）的先进扩散 MRI 建模方法研究了 WMHs 的微观结构特征，该方法可提供每个体素内不同组织隔室的信息。SS3T-CSD 方法可以通过 WMHs 的组织特异性微观结构组成，为病理性组织的解释提供补充信息。数据来自参加认知和中风后皮质体积研究（CANVAS）的中风患者，该研究检查了中风后的脑容量和认知。WMHs 使用基于液体衰减反转恢复（FLAIR）图像的自动方法进行分割。自动组织分割用于识别正常表现的白质（NAWM）。WMHs 根据与脑室的距离（3-10 毫米）分为脑室旁、脑室周围和深部病变。我们旨在比较中风参与者不同 WMH 病变类别的微观结构组成和 NAWM 的组成，以评估这些病变的体内异质性。结果表明，WMHs 类之间和 NAWM 之间的 3 组织组成存在显著差异。具体而言，与深部 WMHs 相比，脑室旁和脑室周围 WMHs 的 3 组织组成均表现出相对较大的类似流体（游离水）含量，这与间质液积聚的存在一致。这些发现为体内 WMHs 的微观结构异质性提供了证据，并可能为理解 WMHs 在血管性神经退行性变中的作用提供新的见解。
