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EPI distortion correction from a simultaneously acquired distortion map using TRAIL
Author(s) -
Priest Andrew N.,
De Vita Enrico,
Thomas David L.,
Ordidge Roger J.
Publication year - 2006
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.20508
Subject(s) - distortion (music) , artificial intelligence , computer vision , computer science , single shot , shot (pellet) , algorithm , mathematics , physics , optics , telecommunications , materials science , amplifier , bandwidth (computing) , metallurgy
Purpose To develop a method for shot‐by‐shot distortion correction of single‐shot echo‐planar imaging (EPI) that is capable of correcting each image individually using a distortion measurement performed during acquisition of the image itself. Materials and Methods The recently‐introduced method known as two reduced acquisitions interleaved (TRAIL) was extended to measure the distribution of the main magnetic field B 0 with each shot. This corresponded to a map of distortion, and allowed distortion to be corrected in the acquired images. Results Distortion‐corrected images were demonstrated in the human brain. The distortion field could be directly visualized using the “stripe” distribution imposed by the TRAIL pulse sequence. This confirmed the success of the correction. Over a time‐course measurement of 10 images, variance was reduced by using shot‐by‐shot distortion correction compared to correction with a constant field map. Conclusion Shot‐by‐shot distortion correction may be performed for EPI images acquired using an extension of the TRAIL technique, ensuring that the correction reflects the actual distortion pattern and not merely a previously measured, but possibly no longer valid, distortion field. This avoids errors due to changes in the distortion field or misregistration of a previously measured distortion map resulting from subject motion. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.