Myocardial ASL-CMR perfusion imaging with improved sensitivity using GRAPPA

Background Myocardial arterial spin labeling (ASL) is a non-contrast CMR technique for measuring myocardial blood flow (MBF), but has relatively low signal-to-physiological noise (PN). Therefore perfusion measurements are made over several averaged pixels within left ventricular (LV) segments and not individual pixels. Shorter image acquisition times using SENSE parallel imaging has been shown to significantly reduce PN and improve sensitivity to MBF. However, SENSE is unable to reconstruct images at a field of view (FOV) smaller than the object being imaged and requires a large FOV, which leads to fewer number of pixels for averaging in the LV. In this study, we demonstrate that GRAPPA parallel imaging (rate 1.6), which has no such FOV restrictions, reduces PN even further than SENSE (rate 2), despite having a longer image acquisition window.