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Single‐shot magnetic field mapping embedded in echo‐planar time‐course imaging
Author(s) -
Roopchansingh Vinai,
Cox Robert W.,
Jesmanowicz Andrzej,
Ward B. Douglas,
Hyde James S.
Publication year - 2003
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.10587
Subject(s) - planar , echo (communications protocol) , magnetic field , field (mathematics) , computer vision , computer science , nuclear magnetic resonance , physics , artificial intelligence , mathematics , computer graphics (images) , computer network , quantum mechanics , pure mathematics
A technique for acquiring magnetic field maps simultaneously with gradient‐recalled echo‐planar time‐course data is described. This technique uses a trajectory in which the central part of k ‐space is collected twice. For a 64 × 64 image acquired with a 125‐kHz bandwidth, a field map suitable for geometric correction can be collected simultaneously with the echo‐planar time‐course data in <70 ms. The field maps generated by this technique are registered with the magnitude images because they are calculated using the same data. They do not suffer from errors due to subject motion, or from different geometric distortions that can result from using different pulse sequences. In addition to correcting geometric distortions that resulted from dynamic magnetic field perturbations, this method was used to measure field shifts arising from respiration and jaw motion across five subjects. Values ranged from 0.035 to 0.165 parts per million (ppm). Magn Reson Med 50:839–843, 2003. © 2003 Wiley‐Liss, Inc.