Test-retest variability underlying fMRI measurements
Test-retest variability underlying fMRI measurements
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DOI：
10.1016/j.neuroimage.2011.11.061
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发表时间：
2012-03-01
期刊：
影响因子：
5.7
通讯作者：
Vink, M.
中科院分区：
文献类型：
--
作者：
Raemaekers, M.;du Plessis, S.;Vink, M.
引言：高的重测信度对于功能磁共振成像研究中的许多学科都是至关重要的。为了评估目前的限制，功能磁共振成像的可靠性，我们估计真正的潜在的血氧水平依赖（BOLD）激活的变化，我们的意思是变异，将被发现在理论上的情况下，我们可以获得无限数量的扫描，在每个measurement.Methods：在这个测试-重测研究中，受试者进行了两次扫描，一个星期分开，同时执行视觉和运动抑制任务。我们解决了潜在的BOLD信号的变异性的性质，通过分离为每个大脑区域和每个主题的BOLD激活的空间模式的会话之间的差异，和全球（整个大脑）的幅度的空间模式的BOLD activation.Results的变化：我们发现的证据在真正的潜在的BOLD激活的空间模式的变化，这两个任务在两个会话。这些模式激活变化的大小约占模式内总激活的16%，与大脑区域和任务无关。空间平滑后，这种变异性大大降低，这表明它发生在一个小的空间尺度。整个大脑的激活幅度的平均会话之间的差异为13.8%的视觉任务和23.4%的运动抑制task.Conclusions：会话之间的变化在真正的基础空间模式的BOLD激活总是存在的，但发生在一个规模，是一致的部分体积效应或空间扭曲。我们没有发现任何证据表明激活的空间模式的可靠性在大脑区域之间存在系统性差异。因此，激活幅度的会话之间的变化可能是由于全局效应。在解释功能磁共振成像对大脑激活高度的估计时，观察到的不同时段的振幅变化值得谨慎。所用算法的Matlab实现可在www.example.com下载。(C)2011 Elsevier Inc. All rights reserved.
Introduction: A high test-retest reliability is of pivotal importance for many disciplines in fMRI research. To assess the current limits of fMRI reliability, we estimated the variability in true underlying Blood Oxygen Level Dependent (BOLD) activation, with which we mean the variability that would be found in the theoretical case when we could obtain an unlimited number of scans in each measurement.Methods: In this test-retest study, subjects were scanned twice with one week apart, while performing a visual and a motor inhibition task. We addressed the nature of the variability in the underlying BOLD signal, by separating for each brain area and each subject the between-session differences in the spatial pattern of BOLD activation, and the global (whole brain) changes in the amplitude of the spatial pattern of BOLD activation.Results: We found evidence for changes in the true underlying spatial pattern of BOLD activation for both tasks across the two sessions. The sizes of these changes in pattern activation were approximately 16% of the total activation within the pattern, irrespective of brain area and task. After spatial smoothing, this variability was greatly reduced, which suggests it takes place at a small spatial scale. The mean between-session differences in the amplitude of activation across the whole brain were 13.8% for the visual task and 23.4% for the motor inhibition task.Conclusions: Between-session changes in the true underlying spatial pattern of BOLD activation are always present, but occur at a scale that is consistent with partial voluming effects or spatial distortions. We found no evidence that the reliability of the spatial pattern of activation differs systematically between brain areas. Consequently, between-session changes in the amplitude of activation are probably due to global effects. The observed variability in amplitude across sessions warrants caution when interpreting fMRI estimates of height of brain activation. A Matlab implementation of the used algorithm is available for download at www.ni-utrecht.nl/downloads/ura. (C) 2011 Elsevier Inc. All rights reserved.