3D single‐shot VASO using a maxwell gradient compensated GRASE sequence |
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Authors: | Benedikt A Poser David G Norris |
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Institution: | 1. Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg‐Essen, Essen, Germany;2. Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging, Radboud University Nijmegen, Nijmegen, The Netherlands |
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Abstract: | The vascular space occupancy (VASO) method was recently proposed as a functional MRI (fMRI) method that is capable of detecting activation‐related changes in blood volume (CBV), without the need for a blood‐pool contrast agent. In the present work we introduce a new whole‐brain VASO technique that is based on a parallel‐accelerated single‐shot 3D GRASE (gradient and spin echo) readout. The GRASE VASO sequence employs a flow‐compensated correction scheme for concomitant Maxwell gradients which is necessary to avoid smearing artifacts that may occur due to violation of the Carr–Purcell–Meiboom–Gill (CPMG) condition for off‐resonance excitation. Experiments with 6 min of visual‐motor stimulation were performed on eight subjects. At P < 0.01, average percent signal change and t‐score for visual stimulation were ?3.11% and ?8.42, respectively; activation in left and right motor cortices and supplementary motor area was detected with ?2.75% and ?6.70, respectively. Sensitivity and signal changes are comparable to those of echo‐planar imaging (EPI)‐based single‐slice VASO, as indicated by additional visual‐task experiments (?3.39% and ?6.93). The method makes it possible to perform whole‐brain cognitive activation studies based on CBV contrast. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc. |
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Keywords: | vascular space occupancy VASO 3D GRASE Maxwell gradient fMRI |
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