Department of Signal Processing, Tampere University of Technology, PO Box 553, FIN-33101 Tampere, Finland.
Magn Reson Imaging. 2013 Jun;31(5):676-87. doi: 10.1016/j.mri.2012.10.021. Epub 2013 Jan 20.
The study of the structural asymmetries in the human brain can assist the early diagnosis and progression of various neuropsychiatric disorders, and give insights into the biological bases of several cognitive deficits. The high inter-subject variability in cortical morphology complicates the detection of abnormal asymmetries especially if only small samples are available. This work introduces a novel automatic method for the local (vertex-level) statistical shape analysis of gross cerebral hemispheric surface asymmetries which is robust to the individual cortical variations. After segmentation of the cerebral hemispheric volumes from three-dimensional (3D) T1-weighted magnetic resonance images (MRI) and their spatial normalization to a common space, the right hemispheric masks were reflected to match with the left ones. Cerebral hemispheric surfaces were extracted using a deformable model-based algorithm which extracted the salient morphological features while establishing the point correspondence between the surfaces. The interhemispheric asymmetry, quantified by customized measures of asymmetry, was evaluated in a few thousands of corresponding surface vertices and tested for statistical significance. The developed method was tested on scans obtained from a small sample of healthy volunteers and first-episode neuroleptic-naïve schizophrenics. A significant main effect of the disease on the local interhemispheric asymmetry was observed, both in females and males, at the frontal and temporal lobes, the latter being often linked to the cognitive, auditory, and memory deficits in schizophrenia. The findings of this study, although need further testing in larger samples, partially replicate previous studies supporting the hypothesis of schizophrenia as a neurodevelopmental disorder.
对人脑结构不对称性的研究可以帮助早期诊断和进展各种神经精神障碍，并深入了解几种认知缺陷的生物学基础。皮质形态的个体间高度变异性使得异常不对称的检测变得复杂，特别是如果只有小样本可用时。这项工作介绍了一种新的自动方法，用于局部（顶点级）统计形状分析大脑半球表面不对称性，该方法对个体皮质变化具有鲁棒性。在对三维（3D）T1 加权磁共振成像（MRI）的大脑半球体积进行分割并将其空间归一化到公共空间后，将右半球掩模反射以与左半球掩模匹配。使用基于变形模型的算法提取大脑半球表面，该算法在建立表面之间的点对应关系的同时提取显著的形态特征。通过自定义的不对称度量来量化半球间的不对称性，并在几千个对应的表面顶点上进行统计显著性测试。所开发的方法在一小部分健康志愿者和首次发作的抗精神病药-naive 精神分裂症患者的扫描中进行了测试。在男女两性的额叶和颞叶都观察到疾病对局部半球间不对称性的显著主效应，后者通常与精神分裂症中的认知、听觉和记忆缺陷有关。尽管这项研究的发现需要在更大的样本中进一步测试，但部分复制了先前支持精神分裂症作为神经发育障碍的假说的研究。
