Selection of the control group for VBM analysis: Influence of covariates, matching and sample size
Selection of the control group for VBM analysis: Influence of covariates, matching and sample size
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DOI：
10.1016/j.neuroimage.2008.02.050
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发表时间：
2008-07-15
期刊：
影响因子：
5.7
通讯作者：
Jackson, Graeme D.
中科院分区：
文献类型：
--
作者：
Pell, Gaby S.;Briellmann, Regula S.;Jackson, Graeme D.
对照组的变异性在基于体素的形态测量（VBM）结构异常检测中起着至关重要的作用。最小化这种方差的两种常见方法是包含协变量以及匹配对照组和患者组。我们解决两个主要问题：VBM 设计中的最佳协变量是什么？当有大量对照可用时，是选择一部分匹配的对照受试者子集（以牺牲数量为代价）更好，还是包括所有可用的对照更好？我们对 176 名对照进行回归分析，以确定性别、年龄和颅内总体积 (TIV) 对体积变化的影响。然后，我们使用不同的匹配和协变量策略来确定海马硬化性癫痫患者异常的 VBM 检测的最佳设计。在回归分析中，随着 TIV 作为附加回归量的加入，焦点性别效应消失了。年龄对焦点体积变化的影响虽小但独特。在 HS 患者的 VBM 分析中，异常检测受到协变量选择的强烈影响。灰质和白质的最佳组合不同（灰质：TIV；颞叶白质：TIV、年龄和性别）。 70-90 名受试者的对照组可以最佳地检测海马体和丘脑的体积损失。在这些群体规模下，匹配的对照组并不总是优于相同规模的故意“不匹配”的群体。通过所有可用的对照受试者获得了体积损失的最佳检测。 (c) 2008 Elsevier Inc. 保留所有权利。
Variability in the control group plays a crucial role in voxel-based morphometry (VBM) detection of structural abnormalities. Two common methods of minimising this variance are inclusion of covariates and matching of control and patient groups. We address two major questions: What are the optimal covariates in the VBM design? When a large pool of controls are available, is it better to choose a subset of matched control subjects at the expense of numbers, or include all available controls?We used regression analysis in a group of 176 controls to determine the contribution of gender, age, and total intracranial volume (TIV) to volume variation. We then used different matching and covariate strategies to determine the optimal design for VBM detection of abnormality in epilepsy patients with hippocampal sclerosis.In the regression analysis, focal gender effects disappeared with inclusion of TIV as an additional regressor. Age had a small but unique contribution to focal volume changes. In the VBM analysis of HS patients, detection of abnormalities was strongly influenced by choice of covariates. The optimal combination was different for grey and white matter (for grey matter: TIV; for temporal lobe white matter: TIV, age and gender). A control group size of 70-90 subjects allowed optimal detection of volume loss in the hippocampus and thalamus. At these group sizes, matched control groups did not consistently prove superior to deliberately "unmatched" groups of the same size. The optimal detection of volume loss was obtained with all available control subjects. (c) 2008 Elsevier Inc. All rights reserved.