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Shearing Distortion Correction for EPI at 7T MRI

Guoxiang Liu and Takashi Ueguchi
Center for Information and Neural Networks, National Institute of Information and Communications Technology and Osaka University, 1-4 Yamadaoka, Suita, Osaka, Japan

Abstract—In Echo Planar Imaging (EPI), the existence of linear geometric distortions due to readout (RO) train-induced background gradients was proven under B0 homogeneity at 3T-MRI. This study was aimed at deriving and implementing a simple method for correcting such kinds of linear geometric distortions at 7T-MRI, without any reference measurements of field errors. The background gradient in the RO direction in the EPI acquisition window was estimated from the phase autocorrelation, which was calculated from the one-dimensional inverse-Fourier-transformed k-space. Our method was implemented on a 7T-MRI whole-body scanner equipped with a gradient insert system, which enables high resolution EPI acquisition with a demand for the distortion correction.

Index Terms—fMRI, distortion, neuroscience

Cite: Guoxiang Liu and Takashi Ueguchi, "Shearing Distortion Correction for EPI at 7T MRI," Vol. 6, No. 3, pp. 151-154, August, 2015. doi: 10.12720/jait.6.3.151-154