Reduction of magnetic field inhomogeneity artifacts in echo planar imaging with SENSE and GESEPI at high field

Geometric distortion, signal‐loss, and image‐blurring artifacts in echo planar imaging (EPI) are caused by frequency shifts and T  2* relaxation distortion of the MR signal along the k‐space trajectory due to magnetic field inhomogeneities. The EPI geometric‐distortion artifact associated with frequency shift can be reduced with parallel imaging techniques such as SENSE, while the signal‐loss and blurring artifacts remain. The gradient‐echo slice excitation profile imaging (GESEPI) method has been shown to be successful in restoring tissue T  2* relaxation characteristics and is therefore effective in reducing signal‐loss and image‐blurring artifacts at a cost of increased acquisition time. The SENSE and GESEPI methods are complementary in artifact reduction. Combining these two techniques produces a method capable of reducing all three types of EPI artifacts while maintaining rapid acquisition time. Magn Reson Med 52:1418–1423, 2004. © 2004 Wiley‐Liss, Inc.

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