A k-space sharing 3D GRASE pseudocontinuous ASL method for whole-brain resting-state functional connectivity

Magnetic resonance imaging (MRI) investigations of resting-state functional connectivity (RSFC) typically use blood oxygen level-dependent (BOLD)-weighted imaging because of its ability to provide whole-brain coverage and high temporal resolution. Single-shot 3D gradient- and spin-echo (GRASE) arterial spin labeling (ASL) offers a number of potential advantages for RSFC measurements, such as a more direct quantitative correlate of neural activity and lower variability across subjects; however, current sequences are usually not suitable for whole-brain acquisitions because of T₂ decay during the long echo train. In this study, we proposed a k-space sharing 3D GRASE ASL sequence to achieve whole-brain coverage, applied it to measure RSFC on a group of healthy subjects, and compared it with BOLD data. Similar RSFC networks were estimated using both techniques, providing corroboration of the capability of our method for RSFC analysis. Furthermore, ASL data enable calculation of mean cerebral blood flow (CBF) values within the RSFC networks, thus assigning them biologically meaningful values. The inherently quantitative nature of CBF measurements should provide a more stable and interpretable biomarker in comparison to BOLD and may, therefore, be particularly useful for applications such as longitudinal studies of RSFC. © 2012 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 22, 37–43, 2012