1 MR Collaboration, Siemens Healthcare China , Beijing, China .
2 Department of Psychiatry (UPK), University of Basel , Basel, Switzerland .
Brain Connect. 2017 Dec;7(10):627-634. doi: 10.1089/brain.2017.0545.
Resting-state functional magnetic resonance imaging (RS-fMRI) is based on the assumption that the vascular response and the blood oxygenation level-dependent response are homogenous across the entire brain. However, this a priori hypothesis is not consistent with the well-known variability of cerebral vascular territories. To explore whether the RS networks are influenced by varied vascular speed in different vascular territories, we assessed the time-shift maps that give an estimate of the local timing of the vascular response and checked whether local differences in this timing have an impact on the estimates of RS networks. Two hundred seventeen elderly (≥60 years), healthy participants (73.74 ± 4.41 years, 143 females, 203 right handed) underwent one MRI examination, including an RS-fMRI session. After preprocessing, statistical analyses included time-shift analyses and RS-fMRI analyses using as regressor the delay maps obtained from the time-shift analyses. The functional connectivity map of default mode network (DMN) of each participant was then calculated by using the seed-to-voxel analysis in the REST toolbox. Faster cerebrovascular responses were notably present in the primary motor and somatosensory and peri-insular cortex, while slower responses were present in various regions, including notably the posterior cingulate cortex (PCC). Moreover, significant changes notably in the DMN, including medial prefrontal cortex (t = 11.95), PCC (t = 11.52), right middle temporal lobe (t = 10.72), and right angular gyrus (t = 10.88), were observed also taking into account the cerebrovascular delayed maps. As the most prominent example of the RS networks, DMN activation patterns change as a function of the cerebrovascular delay. These data suggest that a group correction for vascular maps in RS-fMRI measurements is essential to correctly depict functional differences and exclude potential confounding effects, notably in the elderly with increasing prevalence of vascular comorbidity.
静息态功能磁共振成像（RS-fMRI）基于这样的假设，即整个大脑的血管反应和血氧水平依赖反应是均匀的。然而，这个先验假设与已知的大脑血管区域的可变性不一致。为了探讨 RS 网络是否受到不同血管区域中不同血管速度的影响，我们评估了时间移位图，该图估计了血管反应的局部时间，并检查了这种时间差异是否会对 RS 网络的估计产生影响。217 名老年人（≥60 岁），健康参与者（73.74±4.41 岁，143 名女性，203 名右利手）接受了一次 MRI 检查，包括 RS-fMRI 检查。预处理后，统计分析包括时间移位分析和 RS-fMRI 分析，使用时间移位分析获得的延迟图作为回归量。然后使用 REST 工具包中的种子到体素分析计算每个参与者默认模式网络（DMN）的功能连接图。主要运动和躯体感觉以及岛周皮层的脑血管反应明显较快，而包括后扣带皮层（PCC）在内的多个区域的反应明显较慢。此外，还观察到 DMN 的显著变化，包括内侧前额叶皮层（t=11.95）、PCC（t=11.52）、右侧颞中回（t=10.72）和右侧角回（t=10.88），同时还考虑了脑血管延迟图。作为 RS 网络的最突出示例，DMN 激活模式随脑血管延迟而变化。这些数据表明，在 RS-fMRI 测量中，对血管图进行组校正对于正确描绘功能差异和排除潜在的混杂效应至关重要，特别是在血管合并症患病率不断增加的老年人中。
