✦ LIBER ✦

EPI image reconstruction with correction of distortion and signal losses

✍ Scribed by Guoxiang Liu; Seiji Ogawa

Publisher: John Wiley and Sons
Year: 2006
Tongue: English
Weight: 615 KB
Volume: 24
Category: Article
ISSN: 1053-1807
DOI: 10.1002/jmri.20672

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✦ Synopsis

Abstract

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

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