静息态功能磁共振成像时长对脑网络连接图论度量稳定性的影响。
Effect of resting-state functional MR imaging duration on stability of graph theory metrics of brain network connectivity.
机构信息
Advanced NeuroScience Imaging Research Laboratory, Division of Radiologic Sciences, Department of Radiology, Wake Forest University School of Medicine, Medical Center Blvd, Winston-Salem, NC 27157-1088, USA.
出版信息
Radiology. 2011 May;259(2):516-24. doi: 10.1148/radiol.11101708. Epub 2011 Mar 15.
PURPOSE
To investigate the effect of resting-state (RS) functional magnetic resonance (MR) imaging blood oxygen level-dependent (BOLD) signal acquisition duration on stability of computed graph theory metrics of brain network connectivity.
MATERIALS AND METHODS
An institutional ethics committee approved this study, and informed consent was obtained. BOLD signal (7.5 minutes worth) was obtained from 30 subjects and truncated into 30-second time bins that ranged from 1.5 to 7.5 minutes. A binarized adjacency matrix for each subject and acquisition duration was generated at network costs between 0.1 and 0.5, where network cost is defined as the ratio of the number of edges (connections) in a network to the maximum possible number of edges. Measures of correlation coefficient stability associated with functional connectivity matrices (correlation coefficient standard deviation [SD] and correlation threshold) and associated graph theory metrics (small worldness, local efficiency, and global efficiency) were computed for each subject at each BOLD signal acquisition duration. Computations were implemented with a 15-node 30-core computer cluster to enable analysis of the approximately 2000 resulting brain networks. Analysis of variance and posthoc analyses were conducted to identify differences between time bins for each measure.
RESULTS
Small worldness, local efficiency, and global efficiency stabilized after 2 minutes of BOLD signal acquisition, whereas correlation coefficient data from functional connectivity matrices (correlation coefficient SD and cost-associated threshold) stabilized after 5 minutes of BOLD signal acquisition.
CONCLUSION
Graph theory metrics of brain network connectivity (small worldness, local efficiency, and global efficiency) may be accurately computed from as little as 1.5-2.0 minutes of RS functional MR imaging BOLD signal. As such, implementation of these methods in the context of time-constrained clinical imaging protocols may be feasible and cost-effective.
SUPPLEMENTAL MATERIAL
http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101708/-/DC1.
目的
研究静息态（RS）功能磁共振（MR）成像血氧水平依赖（BOLD）信号采集时间对脑网络连通性计算图论指标稳定性的影响。
材料与方法
本研究经机构伦理委员会批准，所有受试者均签署书面知情同意书。对 30 例受试者进行 BOLD 信号（7.5 分钟采集）采集，并将其分为 30 秒时间箱，时间范围为 1.5 分钟至 7.5 分钟。为每个受试者和每个采集时间生成二进制邻接矩阵，网络成本范围为 0.1 至 0.5，其中网络成本定义为网络中边（连接）的数量与网络中可能存在的最大边数的比值。对每个时间箱的功能连通性矩阵（相关系数标准差[SD]和相关阈值）和相关图论指标（小世界、局部效率和全局效率）进行相关性稳定性测量。使用 15 个节点 30 核计算机集群进行计算，以分析大约 2000 个产生的脑网络。对每个测量值进行方差分析和事后分析，以识别不同时间箱之间的差异。
结果
BOLD 信号采集 2 分钟后，小世界、局部效率和全局效率趋于稳定，而功能连通性矩阵（相关系数 SD 和与成本相关的阈值）的数据在 BOLD 信号采集 5 分钟后趋于稳定。
结论
脑网络连通性的图论指标（小世界、局部效率和全局效率）可以通过 1.5-2.0 分钟 RS 功能 MR 成像 BOLD 信号准确计算。因此，在时间受限的临床成像方案中实施这些方法可能是可行和具有成本效益的。
补充材料
http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101708/-/DC1.
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