Golestani Ali M, Kwinta Jonathan B, Khatamian Yasha B, Chen J Jean
Rotman Research Institute at Baycrest Centre, University of Toronto, Toronto, ON, Canada.
Department of Medical Biophysics, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
Front Neurosci. 2017 Oct 5;11:546. doi: 10.3389/fnins.2017.00546. eCollection 2017.
The resting-state fMRI (rs-fMRI) signal is affected by a variety of low-frequency physiological phenomena, including variations in cardiac-rate (CRV), respiratory-volume (RVT), and end-tidal CO (PETCO). While these effects have become better understood in recent years, the impact that their correction has on the quality of rs-fMRI measurements has yet to be clarified. The objective of this paper is to investigate the effect of correcting for CRV, RVT and PETCO on the rs-fMRI measurements. Nine healthy subjects underwent a test-retest rs-fMRI acquisition using repetition times (TRs) of 2 s (long-TR) and 0.323 s (short-TR), and the data were processed using eight different physiological correction strategies. Subsequently, regional homogeneity (ReHo), amplitude of low-frequency fluctuation (ALFF), and resting-state connectivity of the motor and default-mode networks are calculated for each strategy. Reproducibility is calculated using intra-class correlation and the Dice Coefficient, while the accuracy of functional-connectivity measures is assessed through network separability, sensitivity and specificity. We found that: (1) the reproducibility of the rs-fMRI measures improved significantly after correction for PETCO; (2) separability of functional networks increased after PETCO correction but was not affected by RVT and CRV correction; (3) the effect of physiological correction does not depend on the data sampling-rate; (4) the effect of physiological processes and correction strategies is network-specific. Our findings highlight limitations in our understanding of rs-fMRI quality measures, and underscore the importance of using multiple quality measures to determine the optimal physiological correction strategy.
静息态功能磁共振成像(rs-fMRI)信号受到多种低频生理现象的影响,包括心率变化(CRV)、呼吸量(RVT)和呼气末二氧化碳(PETCO)。虽然近年来对这些影响有了更好的理解,但它们的校正对rs-fMRI测量质量的影响尚未明确。本文的目的是研究校正CRV、RVT和PETCO对rs-fMRI测量的影响。九名健康受试者使用2秒(长TR)和0.323秒(短TR)的重复时间进行了重测rs-fMRI采集,并使用八种不同的生理校正策略对数据进行处理。随后,针对每种策略计算区域同质性(ReHo)、低频波动幅度(ALFF)以及运动和默认模式网络的静息态连接性。使用组内相关性和骰子系数计算可重复性,同时通过网络可分离性、敏感性和特异性评估功能连接性测量的准确性。我们发现:(1)校正PETCO后,rs-fMRI测量的可重复性显著提高;(2)PETCO校正后功能网络的可分离性增加,但不受RVT和CRV校正的影响;(3)生理校正的效果不依赖于数据采样率;(4)生理过程和校正策略的效果具有网络特异性。我们的研究结果突出了我们对rs-fMRI质量测量理解的局限性,并强调了使用多种质量测量来确定最佳生理校正策略的重要性。