• Neil Gelman, Ally Silavi, and Udunna Anazodo.
• Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada; Department of Medical Imaging, University of Western Ontario, London, Ontario, Canada; Department of Lawson Health Research Institute, London, Ontario, Canada. Electronic address: ngelman@lawsonimaging.ca.
• Magn Reson Imaging. 2014 Jun 1; 32 (5): 590-3.

AbstractA hybrid strategy for geometric distortion correction of echo-planar images is demonstrated. This procedure utilizes standard field mapping for signal displacement correction and the so-called reverse gradient acquisition for signal intensity correction. (The term reverse gradient refers to an acquisition of two sets of echo-planar images with phase encoding gradients of opposite polarity.) The hybrid strategy is applied to human brain echo-planar images acquired with and without diffusion-weighting. A comparison of the hybrid distortion corrected images to those corrected with standard field mapping only demonstrates much better performance of the hybrid method. A variant of the hybrid method is also demonstrated which requires the acquisition of only one pair of opposite polarity images within a set of images.Copyright © 2014 Elsevier Inc. All rights reserved.

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