Cui, Bray, Bryant, Glover, Reiss (2011) A quantitative comparison of NIRS and fMRI across multiple cognitive tasks NeuroImage 54(4) 2808-21


Near infrared spectroscopy (NIRS) is an increasingly popular technology for studying brain function. NIRS presents several advantages relative to functional magnetic resonance imaging (fMRI), such as measurement of concentration changes in both oxygenated and deoxygenated hemoglobin, finer temporal resolution, and ease of administration, as well as disadvantages, most prominently inferior spatial resolution and decreased signal-to-noise ratio (SNR). While fMRI has become the gold standard for in vivo imaging of the human brain, in practice NIRS is a more convenient and less expensive technology than fMRI. It is therefore of interest to many researchers how NIRS compares to fMRI in studies of brain function. In the present study we scanned participants with simultaneous NIRS and fMRI on a battery of cognitive tasks, placing NIRS probes over both frontal and parietal brain regions. We performed detailed comparisons of the signals in both temporal and spatial domains. We found that NIRS signals have significantly weaker SNR, but are nonetheless often highly correlated with fMRI measurements. Both SNR and the distance between the scalp and the brain contributed to variability in the NIRS/fMRI correlations. In the spatial domain, we found that a photon path forming an ellipse between the NIRS emitter and detector correlated most strongly with the BOLD response. Taken together these findings suggest that, while NIRS can be an appropriate substitute for fMRI for studying brain activity related to cognitive tasks, care should be taken when designing studies with NIRS to ensure that: 1) the spatial resolution is adequate for answering the question of interest and 2) the design accounts for weaker SNR, especially in brain regions more distal from the scalp. Copyright © 2010 Elsevier Inc. All rights reserved.

近红外光谱(NIRS)是一种越来越流行的技术,用于研究脑功能。 NIRS提供了相对于功能磁共振成像(fMRI)的若干优点,例如测量氧合和脱氧血红蛋白中的浓度变化,更精细的时间分辨率和易于施用,以及缺点,最显着地较差的空间分辨率和降低的信号 - 信噪比(SNR)。虽然fMRI已经成为人类大脑的体内成像的金标准,但在实践中NIRS是比fMRI更方便和更便宜的技术。因此,许多研究人员如何在大脑功能研究NIRS与fMRI比较感兴趣。在本研究中,我们扫描参与者同时NIRS和fMRI的一系列认知任务,将NIRS探针放在额叶和顶叶区域。我们对时间和空间域中的信号进行了详细的比较。我们发现NIRS信号具有显着较弱的SNR,但是通常与fMRI测量高度相关。 SNR和头皮和大脑之间的距离都有助于NIRS / fMRI相关性的变异性。在空间域中,我们发现在NIRS发射器和检测器之间形成椭圆的光子路径与BOLD响应最强相关。综上所述,这些研究结果表明,尽管NIRS可以是fMRI的适当替代,用于研究与认知任务相关的大脑活动,但在设计使用NIRS的研究时应当小心,以确保:1)空间分辨率足以回答兴趣和2)设计说明较弱的SNR,特别是在远离头皮的脑区域。