Reliability correction for functional connectivity: Theory and implementation.
Reliability correction for functional connectivity: Theory and implementation.
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DOI：
10.1002/hbm.22947
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发表时间：
2015-11
影响因子：
4.8
通讯作者：
Liu H
中科院分区：
文献类型：
--
作者：
Mueller S;Wang D;Fox MD;Pan R;Lu J;Li K;Sun W;Buckner RL;Liu H
网络属性可以使用功能连接MRI （fcMRI）来估计。然而，fMRI信号的区域差异会导致网络估计的系统性偏差，包括低测量可靠性区域的相关衰减。在这里，我们使用纵向fcMRI数据集计算了fcMRI可靠性的空间分布，并演示了预估计的可靠性图如何校正相关衰减。作为基于可靠性的衰减校正的测试案例，我们估计了默认网络的特性，其中内侧颞叶的可靠性明显低于平均水平，后内侧皮层的可靠性高于平均水平，异质性影响了网络的估计。使用衰减校正来解释这种偏差，表明内侧颞叶对默认网络的贡献通常被低估了。为了使这种方法对更多的数据集有用，我们证明了在单个扫描会话中重复运行得出的测试-重测试可靠性映射可以用作多会话可靠性映射的替代。在1 ~ 30min不同扫描长度的数据段中，我们发现连通性估计的重测信度随着扫描长度的增加而增加，而在较短的扫描长度下，可靠性的空间分布相对稳定。最后，对三级数据的分析显示，信度分布受年龄、神经精神状态和扫描仪类型的影响，这表明在研究组间差异时，信度校正可能特别重要。总之，这些结果表明，基于可靠性的衰减校正是一种易于实现的策略，可以减轻fMRI信号不均匀性的某些特征。
Network properties can be estimated using functional connectivity MRI (fcMRI). However, regional variation of the fMRI signal causes systematic biases in network estimates including correlation attenuation in regions of low measurement reliability. Here we computed the spatial distribution of fcMRI reliability using longitudinal fcMRI datasets and demonstrated how pre-estimated reliability maps can correct for correlation attenuation. As a test case of reliability-based attenuation correction we estimated properties of the default network, where reliability was significantly lower than average in the medial temporal lobe and higher in the posterior medial cortex, heterogeneity that impacts estimation of the network. Accounting for this bias using attenuation correction revealed that the medial temporal lobe’s contribution to the default network is typically underestimated. To render this approach useful to a greater number of datasets, we demonstrate that test-retest reliability maps derived from repeated runs within a single scanning session can be used as a surrogate for multi-session reliability mapping. Using data segments with different scan lengths between 1 and 30 min, we found that test-retest reliability of connectivity estimates increases with scan length while the spatial distribution of reliability is relatively stable even at short scan lengths. Finally, analyses of tertiary data revealed that reliability distribution is influenced by age, neuropsychiatric status and scanner type, suggesting that reliability correction may be especially important when studying between-group differences. Collectively, these results illustrate that reliability-based attenuation correction is an easily implemented strategy that mitigates certain features of fMRI signal nonuniformity.