Raemaekers M, Vink M, Zandbelt B, van Wezel R J A, Kahn R S, Ramsey N F
Helmholtz Institute, Department of Functional Neurobiology, University of Utrecht, The Netherlands.
Neuroimage. 2007 Jul 1;36(3):532-42. doi: 10.1016/j.neuroimage.2007.03.061. Epub 2007 Apr 11.
Various studies have investigated reproducibility of fMRI results. Whereas group results can be highly reproducible, individual activity maps tend to vary across sessions. Individual reliability is of importance for the application of fMRI in endophenotype research, where brain activity is linked to genetic polymorphisms. In this study, the test-retest reliability of activation maps during the antisaccade paradigm was assessed for individual and group results. Functional MRI images were acquired during two sessions of prosaccades and antisaccades in twelve healthy subjects using an event-related fMRI design. Reliability was assessed for both individual and group-wise results. In addition, the reliability of differences between subjects was established in predefined regions of interest. The reliability of group activation maps was high for prosaccades and antisaccades, but only moderate for antisaccades vs. prosaccades, probably as a result of low statistical power of individual results. Reproducibility of individual subject maps was highly variable, indicating that reliable results can be obtained in some but not all subjects. Reliability of individual activity maps was largely explained by individual differences in the global temporal signal to noise ratio (SNR). As the global SNR was stable over sessions, it explained a large portion of the differences between subjects in regional brain activation. A low SNR in some subjects may be dealt with either by improving the statistical sensitivity of the fMRI procedure or by subject exclusion. Differences in the global SNR between subjects should be addressed before using regional brain activation as phenotype in genetic studies.
多项研究调查了功能磁共振成像（fMRI）结果的可重复性。尽管群体结果可能具有高度可重复性，但个体活动图谱在不同实验环节往往会有所不同。个体可靠性对于fMRI在表型研究中的应用至关重要，在该研究中大脑活动与基因多态性相关。在本研究中，针对个体和群体结果评估了反扫视范式期间激活图谱的重测可靠性。使用事件相关fMRI设计，在12名健康受试者的两次顺向扫视和反向扫视实验环节中采集功能磁共振图像。对个体和群体层面的结果都进行了可靠性评估。此外，还在预定义的感兴趣区域确定了受试者之间差异的可靠性。顺向扫视和反向扫视的群体激活图谱可靠性较高，但反向扫视与顺向扫视相比的可靠性仅为中等，这可能是个体结果统计效力较低的结果。个体受试者图谱的可重复性差异很大，表明在部分而非所有受试者中都能获得可靠结果。个体活动图谱的可靠性很大程度上由全局时间信噪比（SNR）的个体差异所解释。由于全局SNR在各实验环节中稳定，它解释了区域脑激活中受试者之间差异的很大一部分。对于一些SNR较低的受试者，可以通过提高fMRI程序的统计敏感性或排除受试者来解决。在基因研究中将区域脑激活用作表型之前，应先解决受试者之间全局SNR的差异问题。
