A constrained slice‐dependent background suppression scheme for simultaneous multislice pseudo‐continuous arterial spin labeling

Purpose To present a constrained slice-dependent (CSD) background-suppression (BS) scheme in 2D arterial spin labeling (ASL) using simultaneous multislice acquisition with blipped-CAIPIRINHA (controlled aliasing in parallel imaging results in higher acceleration). Methods Background suppression for 2D acquisition is challenging because of the multiple nulling points required for sequential slice readout. Constrained slice-dependent BS exploits the simultaneous multislice technique to reduce the readout duration, and uses slice-dependent premodulation pulses to achieve BS across slice groups. The proposed scheme was evaluated by in vivo brain experiments at 3 Tesla with multiband acceleration factors up to four. The utility of CSD BS was demonstrated through comparison against standard 2D acquisitions as well as 3D-BS pseudo-continuous ASL (pCASL). Results An average of 95% background signal reduction was achieved with CSD BS. As a result, the temporal signal-to-noise ratio (SNR) increased 48.2/39.9/36.9/36.0% and spatial SNR increased 132.5/80.0/63.5/54.2 in CSD-BS MB-1/2/3/4 scans, respectively. Whole-brain coverage was achievable with CSD-BS pCASL with MB-4, which yielded comparable spatial SNR as 3D BS pCASL. Conclusions The proposed CSD-BS scheme for 2D-SMS pCASL offers a promising approach for effective suppression of background signals across a wide range of T1 to achieve whole-brain perfusion imaging. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine.