Resting fluctuations in arterial carbon dioxide induce significant low frequency variations in BOLD signal
Resting fluctuations in arterial carbon dioxide induce significant low frequency variations in BOLD signal
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DOI：
10.1016/j.neuroimage.2003.11.025
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发表时间：
2004-04-01
期刊：
影响因子：
5.7
通讯作者：
Tracey, I
中科院分区：
文献类型：
--
作者：
Wise, RG;Ide, K;Tracey, I
二氧化碳是一种有效的脑血管扩张剂。我们已经确定了一个显着的来源，低频变化的血氧水平依赖性（BOLD）磁共振成像（MRI）信号在3 T所产生的自发波动，在休息时的志愿者动脉二氧化碳水平。在9名志愿者组成的队列中，在0-0.05 Hz频率范围内观察到呼气末二氧化碳分压（PETCO 2）波动为+/- 1.1 mm Hg。与这些波动相关的是显着的广义灰色和白色物质BOLD信号波动。我们观察到组间平均（标准误差）回归系数为：灰质每mmHg CO2 BOLD信号变化0.110 +/- 0.033%，白色物质每mmHg CO2 BOLD信号变化0.049 +/- 0.022%。PETCO 2相关的BOLD信号波动显示了整个灰质的区域差异，表明静息时对二氧化碳的反应性存在差异。功能性磁共振成像（fMRI）的结果证实了经颅多普勒（TCD）超声测量大脑中动脉（MCA）血流速度在一个队列的四名志愿者。观察到MCA血流速度的显著PETCO 2相关波动，PETCO 2变化滞后6.3 +/- 1.2 s（平均标准误差）。在BOLD信号的分析中采用了这种血液动力学滞后。多普勒超声表明，低频BOLD信号波动的一个组成部分是由CO2诱导的脑血流量（CBF）的变化介导的。这些波动是生理噪声的来源，也是改变呼吸的功能磁共振成像范例中潜在的重要混杂因素。然而，它们也可用于绘制局部血管对CO2的反应性。(C)2004年爱思唯尔公司All rights reserved.
Carbon dioxide is a potent cerebral vasodilator. We have identified a significant source of low-frequency variation in blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) signal at 3 T arising from spontaneous fluctuations in arterial carbon dioxide level in volunteers at rest. Fluctuations in the partial pressure of end-tidal carbon dioxide (PETCO2) of +/- 1.1 mm Hg in the frequency range 0-0.05 Hz were observed in a cohort of nine volunteers. Correlating with these fluctuations were significant generalized grey and white matter BOLD signal fluctuations. We observed a mean ( standard error) regression coefficient across the group of 0.110 +/- 0.033% BOLD signal change per nun Hg CO2 for grey matter and 0.049 +/- 0.022% per mm Hg in white matter. PETCO2-related BOLD signal fluctuations showed regional differences across the grey matter, suggesting variability of the responsiveness to carbon dioxide at rest. Functional magnetic resonance imaging (fMRI) results were corroborated by transcranial Doppler (TCD) ultrasound measurements of the middle cerebral artery (MCA) blood velocity in a cohort of four volunteers. Significant PETCO2-correlated fluctuations in MCA blood velocity were observed with a lag of 6.3 +/- 1.2 s (mean standard error) with respect to PETCO2 changes. This haemodynamic lag was adopted in the analysis of the BOLD signal. Doppler ultrasound suggests that a component of low-frequency BOLD signal fluctuations is mediated by CO2-induced changes in cerebral blood flow (CBF). These fluctuations are a source of physiological noise and a potentially important confounding factor in fMRI paradigms that modify breathing. However, they can also be used for mapping regional vascular responsiveness to CO2. (C) 2004 Elsevier Inc. All rights reserved.