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Improved echo volumar imaging (EVI) for functional MRI
Author(s) -
van der Zwaag Wietske,
Francis Susan,
Bowtell Richard
Publication year - 2006
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.21080
Subject(s) - ghosting , echo planar imaging , computer science , sampling (signal processing) , scanner , calibration , sensitivity (control systems) , nuclear medicine , nuclear magnetic resonance , artificial intelligence , magnetic resonance imaging , physics , computer vision , medicine , radiology , filter (signal processing) , quantum mechanics , electronic engineering , engineering
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.