Correction for EPI distortions using multi-echo gradient-echo imaging.
A novel and effective technique is described for distortion correction in echo planar imaging (EPI) utilizing the field maps derived from multi-echo gradient-echo images. The distortions from different off-resonance related factors such as field inhomogeneity, eddy current effect, radiofrequency pulse frequency offset, and chemical shift effect can be simultaneously reduced to a great extent. With the proposed post-processing algorithm of multi-channel modulation, distortions may be corrected without unwrapping the phase discontinuities in the derived field map, a process that usually restricts the application of other field map-based correction methods. Results from phantom and animal experiments at 4.7 T demonstrate the efficiency of the method in reducing the geometrical distortions in gradient-echo EPI.
Chen
N K
NK
Center for MR Research, Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60201, USA.
Wyrwicz
A M
AM
D000465:Algorithms; D000818:Animals; D001921:Brain / Q000033:anatomy & histology; D017352:Echo-Planar Imaging / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D019047:Phantoms, Imaging; D011817:Rabbits