Whole-brain analysis reveals increased neuroanatomical asymmetries in dementia for hippocampus and amygdala
Whole-brain analysis reveals increased neuroanatomical asymmetries in dementia for hippocampus and amygdala
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DOI：
10.1093/brain/aww243
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发表时间：
2016-12-01
期刊：
影响因子：
14.5
通讯作者：
Reuter, Martin
中科院分区：
文献类型：
--
作者：
Wachinger, Christian;Salat, David H.;Reuter, Martin
结构磁共振成像数据经常被分析，以揭示痴呆症人脑的形态学变化。大多数当代成像生物标志物是标量值，例如结构的体积，并且可能错过早期症状前疾病进展的局部形态变化。然而，神经解剖形状描述符，可以代表复杂的几何信息的个别解剖区域，并可能表现出增加的敏感性，在关联研究。然而，它们在很大程度上仍未被探索。在这篇文章中，我们介绍了一种新的技术来研究形状不对称的神经解剖结构在皮层下和皮层脑区。我们证明，在阿尔茨海默氏病皮层下结构的神经变性是不对称的。海马体显示出纵向不对称性的显著增加，海马体和杏仁核均显示出显著更高的不对称性横截面与疾病严重程度同时发生，并且超出了老化效应。我们的研究结果进一步表明，在这些结构的不对称是无方向性的，主要是前海马成为不对称。基于纵向不对称措施，我们随后研究了从轻度认知障碍到痴呆的进展，表明海马、杏仁核、尾状核和皮质的形状不对称是疾病发作的预测因素。对标量体积测量的相同分析没有产生任何显著的结果，表明可能由亚核中的形态测量变化引起的形状不对称，而不是大小不对称与疾病进展相关，并且可以产生用于早期症状前分类和预测阿尔茨海默病的强大的成像生物标志物。由于文献集中在对侧的体积差异，皮质下疾病的偏侧化可能被忽视了。
Structural magnetic resonance imaging data are frequently analysed to reveal morphological changes of the human brain in dementia. Most contemporary imaging biomarkers are scalar values, such as the volume of a structure, and may miss the localized morphological variation of early presymptomatic disease progression. Neuroanatomical shape descriptors, however, can represent complex geometric information of individual anatomical regions and may demonstrate increased sensitivity in association studies. Yet, they remain largely unexplored. In this article, we introduce a novel technique to study shape asymmetries of neuroanatomical structures across subcortical and cortical brain regions. We demonstrate that neurodegeneration of subcortical structures in Alzheimer's disease is not symmetric. The hippocampus shows a significant increase in asymmetry longitudinally and both hippocampus and amygdala show a significantly higher asymmetry cross-sectionally concurrent with disease severity above and beyond an ageing effect. Our results further suggest that the asymmetry in these structures is undirectional and that primarily the anterior hippocampus becomes asymmetric. Based on longitudinal asymmetry measures we subsequently study the progression from mild cognitive impairment to dementia, demonstrating that shape asymmetry in hippocampus, amygdala, caudate and cortex is predictive of disease onset. The same analyses on scalar volume measurements did not produce any significant results, indicating that shape asymmetries, potentially induced by morphometric changes in subnuclei, rather than size asymmetries are associated with disease progression and can yield a powerful imaging biomarker for the early presymptomatic classification and prediction of Alzheimer's disease. Because literature has focused on contralateral volume differences, subcortical disease lateralization may have been overlooked thus far.