Perfusion-based functional magnetic resonance imaging with single-shot RARE and GRASE acquisitions

For perfusion-based functional magnetic resonance imaging, the previously i ntroduced flow-sensitive alternating inversion recovery (FAIR) technique is combined with single-shot RARE (rapid acquisition with relaxation enhancem ent) and GRASE (gradient and spin echo) imaging sequences. The advantages o f these sequences compared to commonly used echo-planar imaging (EPI) are a n increased signal-to-noise ratio and the absence of distortions and artifa cts due to magnetic field inhomogeneities. RARE- and GRASE-FAIR are applied to functional brain mapping studies in humans during visual stimulation. R esults demonstrate that the presented techniques allow for perfusion maps w ith higher spatial resolution compared to EPI-FAIR. Relative regional cereb ral blood flow change in the occipital cortex during visual stimulation was measured to be 41 +/- 4% (n = 5). The comparison of FAIR data obtained wit h RARE and GRASE techniques shows that RARE yields images with the higher s ignal-to-noise ratio. However, the GRASE technique features a shorter acqui sition time and less RF power deposition and is thus better suited for mult i-slice acquisitions. Magn Reson Med 41:132-136, 1999. (C) 1999 Wiley-Liss, Inc.