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Single-shot 3D GRASE with cylindrical k-space trajectories

✍ Scribed by S. Ramanna; D.A. Feinberg

Publisher: John Wiley and Sons
Year: 2008
Tongue: English
Weight: 457 KB
Volume: 60
Category: Article
ISSN: 0740-3194
DOI: 10.1002/mrm.21735

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✦ Synopsis

Abstract

Development of GRASE (gradient‐ and spin‐echo) pulse sequences for single‐shot 3D imaging has been motivated by physiologic studies of the brain. The duration of echo‐planar imaging (EPI) subsequences between RF refocusing pulses in the GRASE sequence is determinant of image distortions and susceptibility artifacts. To reduce these artifacts the regular Cartesian trajectory is modified to a circular trajectory in 2D and a cylindrical trajectory in 3D for reduced echo train time. Incorporation of “fly‐back” trajectories lengthened the time of the subsequences and proportionally increased susceptibility artifact but the unipolar readout gradients eliminate all ghost artifacts. The modified cylindrical trajectory reduced susceptibility artifact and distortion artifact while raising the signal‐to‐noise ratio in both phantom and human brain images. Magn Reson Med 60:976–980, 2008. © 2008 Wiley‐Liss, Inc.

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