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A hybrid strategy for correcting geometric distortion in echo-planar images |
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| Authors: | Neil Gelman Ally Silavi Udunna Anazodo |
| Institution: | 1. Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada;2. Department of Medical Imaging, University of Western Ontario, London, Ontario, Canada;3. Department of Lawson Health Research Institute, London, Ontario, Canada |
| Abstract: | A 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. |
| Keywords: | Geometric distortion correction Echo planar imaging Reverse phase encode gradient acquisition Field mapping Diffusion weighted imaging |
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