Perfusion-based brain connectivity: PASL vs PCASL

Arterial Spin Labelling (ASL) is a magnetic resonance imaging technique which provides a more direct measure of neural activity as compared to blood-oxygenation-level-dependent (BOLD) contrast. While it has been used for years for perfusion quantification, ASL has recently been adopted for functional connectivity (FC) analyses. However, the impact of the different ASL schemes on connectivity estimates remains to be fully investigated. In this work, pulsed and pseudo continuous ASL (PASL/pCASL) were compared in terms of cerebral blood flow (CBF) and FC measures. In line with literature, higher CBF and increased spatial signal-to-noise ratio were reported for pCASL, as compared to PASL. In terms of FC, pCASL was able to more reliably recover the main networks and showed higher correlations between brain areas. These preliminary results suggest pCASL to provide reliable and stable results, not only for CBF estimation but also for FC analyses.