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Detection and correction of frequency instabilities for volumetric 1 H echo‐planar spectroscopic imaging
Author(s) -
Ebel Andreas,
Maudsley Andrew A.
Publication year - 2005
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.20367
Subject(s) - nuclear magnetic resonance , signal (programming language) , distortion (music) , magnetic resonance spectroscopic imaging , echo planar imaging , planar , echo (communications protocol) , physics , energy (signal processing) , echo time , resonance (particle physics) , magnetic resonance imaging , spectral line , materials science , optics , atomic physics , computer science , medicine , amplifier , computer network , computer graphics (images) , optoelectronics , cmos , quantum mechanics , radiology , programming language , astronomy
Spectral quality in 1 H magnetic resonance spectroscopic imaging (MRSI) critically depends on the stability of the main magnetic field. For echo‐planar MRSI implemented at 3 T, temperature variation in the passive steel shims of the magnet system can lead to a significant drift in the resonance frequency. A method is presented that incorporates interleaved measurement of the instantaneous resonance frequency of a reference water signal into a volumetric MRSI sequence and allows correction for the drift during postprocessing. Results from normal human brain at 3 T indicate that the correction largely removes lineshape distortions, recovers metabolite signal loss, and improves spectral quality by reducing the width of spectral lines; however, particularly in inferior regions, other sources of distortion may be present that cause broadening of spectral lines. Magn Reson Med 53:465–469, 2005. © 2005 Wiley‐Liss, Inc.