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EPI image reconstruction with correction of distortion and signal losses
Author(s) -
Liu Guoxiang,
Ogawa Seiji
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.20672
Subject(s) - k space , imaging phantom , signal (programming language) , distortion (music) , fourier transform , kernel (algebra) , computer science , physics , iterative reconstruction , echo planar imaging , inverse , nuclear magnetic resonance , algorithm , artificial intelligence , computer vision , magnetic resonance imaging , mathematics , mathematical analysis , optics , geometry , medicine , amplifier , combinatorics , radiology , programming language , computer network , bandwidth (computing)
Purpose To derive and implement a method for correcting geometric distortions and recovering magnetic resonance imaging (MRI) signal losses caused by susceptibility‐induced magnetic field gradients (SFGs) in regions with large static field inhomogeneities in echo‐planar imaging (EPI). Materials and Methods Factors to account for field inhomogeneities and SFGs were added in a traditional EPI equation that was a simple Fourier transform (FT) for expressing the actual k‐space data of an EPI scan. The inverse calculation of this “distorted EPI” equation was used as a kernel to correct geometric distortions and reductions in intensity during reconstruction. A step‐by‐step EPI reconstruction method was developed to prevent complicated phase unwrapping problems. Some EPI images of phantom and human brains were reconstructed from standard EPI k‐spaces. Results All images were reconstructed using the proposed multistep method. Geometric distortions were corrected and SFG‐induced MRI signal losses were recovered. Conclusion Results suggest that applying our method for reconstructing EPI images to reduce distortions and MRI signal losses is feasible. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.