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Title: A variable flip angle-based method for reducing blurring in 3D GRASE ASL.
Austin Authors: Liang, Xiaoyun;Connelly, Alan;Tournier, Jacques-Donald;Calamante, Fernando
Affiliation: Florey Institute of Neuroscience and Mental Health, Heidelberg, Victoria, Australia
Issue Date: 29-Aug-2014
Publication information: Physics in Medicine and Biology 2014; 59(18): 5559-73
Abstract: Arterial Spin Labeling (ASL) is an MRI technique to measure cerebral blood flow directly and noninvasively, and thus provides a more direct quantitative correlate of neural activity than blood-oxygen-level-dependent fMRI. A 3D gradient and spin-echo (GRASE) sequence is capable of enhancing signal-to-noise ratio, and has been shown to be a very useful readout module for ASL sequences. Nonetheless, the introduction of significant blurring in its single-shot version, due to T2 decay along the partition dimension, compromises the achievable spatial resolution, limiting the potential of this technique for whole-brain coverage. To address this issue, a method for reducing blurring based on a variable flip angle (VFA) scheme is proposed in this study for 3D GRASE ASL perfusion. Numerical simulations show that the proposed method is capable of reducing the blurring significantly compared to the standard constant flip angle approach; this result was further confirmed using in vivo data. The proposed VFA method should therefore be of significance to 3D GRASE ASL fMRI studies, since it is able to reduce blurring without sacrificing temporal resolution.
Gov't Doc #: 25170985
DOI: 10.1088/0031-9155/59/18/5559
Journal: Physics in medicine and biology
Type: Journal Article
Appears in Collections:Journal articles

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