Improved echo volumar imaging (EVI) for functional MRI

Authors

  • Wietske van der Zwaag,

    1. Sir Peter Mansfield Magnetic Resonance Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
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  • Susan Francis,

    1. Sir Peter Mansfield Magnetic Resonance Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
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  • Richard Bowtell

    Corresponding author
    1. Sir Peter Mansfield Magnetic Resonance Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
    • Sir Peter Mansfield Magnetic Resonance Centre, School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
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  • Presented in part at the 13th Annual Meeting of ISMRM, Miami Beach, FL, USA, 2005.

Abstract

Echo volumar imaging (EVI) is a 3D modification of echo-planar imaging (EPI) that allows data from an entire volume to be acquired following a single RF excitation. EVI provides a high rate of volumar data acquisition, which is advantageous for functional MRI (fMRI). However, few studies to date have applied EVI to fMRI, since because of gradient hardware limitations EVI generally has to be used with long sampling times, resulting in high sensitivity to susceptibility-induced distortions. In this study we modified the EVI sequence to improve its suitability for fMRI. The sampling time is reduced by the use of a high gradient-switching frequency, a small number of echoes, and outer volume suppression (OVS); rewind gradients ameliorate Nyquist ghosting; and phase correction via a calibration scan reduces ghosting and distortion. It is shown that the modified EVI sequence allows fMRI data to be acquired with a temporal resolution of 167 ms. Magn Reson Med, 2006. © 2006 Wiley-Liss, Inc.

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