Jahanshad Neda, Kohannim Omid, Toga Arthur W, McMahon Katie L, de Zubicaray Greig I, Hansell Narelle K, Montgomery Grant W, Martin Nicholas G, Wright Margaret J, Thompson Paul M
Laboratory of Neuro Imaging, Department of Neurology, UCLA School of Medicine, Los Angeles, CA.
Proc IEEE Int Symp Biomed Imaging. 2012:944-947. doi: 10.1109/ISBI.2012.6235712.
Large multi-site image-analysis studies have successfully discovered genetic variants that affect brain structure in tens of thousands of subjects scanned worldwide. Candidate genes have also associated with brain integrity, measured using fractional anisotropy in diffusion tensor images (DTI). To evaluate the heritability and robustness of DTI measures as a target for genetic analysis, we compared 417 twins and siblings scanned on the same day on the same high field scanner (4-Tesla) with two protocols: (1) 94-directions; 2mm-thick slices, (2) 27-directions; 5mm-thickness. Using mean FA in white matter ROIs and FA 'skeletons' derived using FSL, we (1) examined differences in voxelwise means, variances, and correlations among the measures; and (2) assessed heritability with structural equation models, using the classical twin design. FA measures from the genu of the corpus callosum were highly heritable, regardless of protocol. Genome-wide analysis of the genu mean FA revealed differences across protocols in the top associations.
大型多中心图像分析研究已成功发现了影响全球数以万计接受扫描受试者脑结构的基因变异。候选基因也与脑完整性相关，脑完整性通过扩散张量成像（DTI）中的分数各向异性来衡量。为了评估DTI测量作为遗传分析靶点的遗传性和稳健性，我们使用两种方案对417对双胞胎和兄弟姐妹进行了同一天在同一台高场扫描仪（4特斯拉）上的扫描：（1）94个方向；2毫米厚切片，（2）27个方向；5毫米厚切片。使用白质感兴趣区域的平均FA以及使用FSL得出的FA“骨架”，我们（1）检查了测量值在体素均值、方差和相关性方面的差异；（2）使用经典双胞胎设计，通过结构方程模型评估遗传性。无论采用何种方案，胼胝体膝部的FA测量值都具有高度遗传性。对胼胝体膝部平均FA进行全基因组分析发现，顶级关联在不同方案之间存在差异。
