Abstract
Resting-state brain activity has been widely investigated using blood oxygenation level dependent (BOLD) contrast techniques. However, BOLD signal changes reflect a combination of the effects of cerebral blood flow (CBF), cerebral blood volume (CBV), as well as the cerebral metabolic rate of oxygen (CMRO2). In this study, resting-state brain activation was detected and compared using the following techniques: (a) BOLD, using a gradient-echo echo planar imaging (GE-EPI) sequence; (b) CBV-weighted signal, acquired using gradient and spin echo (GRASE) based vascular space occupancy (VASO); and (c) CBF, using pseudo-continuous arterial spin labeling (pCASL). Reliable brain networks were detected using VASO and ASL, including sensorimotor, auditory, primary visual, higher visual, default mode, salience and left/right executive control networks. Differences between the resting-state activation detected with ASL, VASO and BOLD could potentially be due to the different temporal signal-to-noise ratio (tSNR) and the short post-labeling delay (PLD) in ASL, along with differences in the spin-echo readout of VASO. It is also possible that the dynamics of spontaneous fluctuations in BOLD, CBV and CBF could differ due to biological reasons, according to their location within the brain.
Highlights
The measurement of functional connectivity (FC) in the resting state has been a powerful method with which to characterize the intrinsic functional architecture of the brain (Biswal et al, 1995; Greicius et al, 2003; Fox et al, 2005)
It is possible that the dynamics of spontaneous fluctuations in cerebral blood flow (CBF), cerebral blood volume (CBV) and blood oxygenation level dependent (BOLD) differ depending on their location within the brain
This study demonstrates a comparison of resting-state brain activation detected by three different contrasts, including BOLD, CBV and CBF
Summary
The measurement of functional connectivity (FC) in the resting state has been a powerful method with which to characterize the intrinsic functional architecture of the brain (Biswal et al, 1995; Greicius et al, 2003; Fox et al, 2005). It is possible to acquire functional signals using magnetic resonance imaging (MRI) based on blood oxygenation level dependent (BOLD) contrast, cerebral blood flow (CBF), cerebral blood volume (CBV) and cerebral metabolic rate of oxygen (CMRO2). Among these techniques, resting-state BOLD fMRI is the most widely used. BOLD signal changes reflect a combination of effects from blood oxygenation, CBV, CBF and CMRO2 (Davis et al, 1998; Hoge et al, 1999; Buxton et al, 2004). Imaging techniques based on the physiological parameters of CBV, CBF or CMRO2 are collected
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