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Impact of frequency drift on gamma‐aminobutyric acid‐edited MR spectroscopy
Author(s) -
Harris Ashley D.,
Glaubitz Benjamin,
Near Jamie,
John Evans C.,
Puts Nicolaas A.J.,
SchmidtWilcke Tobias,
Tegenthoff Martin,
Barker Peter B.,
Edden Richard A.E.
Publication year - 2014
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.25009
Subject(s) - subtraction , nuclear magnetic resonance , gamma aminobutyric acid , physics , computer science , chemistry , mathematics , biochemistry , receptor , arithmetic
Purpose To investigate the quantitative impact of frequency drift on Gamma‐Aminobutyric acid (GABA+)‐edited MRS of the human brain at 3 Tesla (T). Methods Three sequential GABA+‐edited MEGA‐PRESS acquisitions were acquired in fifteen sessions; in ten of these, MRS was preceded by functional MRI (fMRI) to induce frequency drift, which was estimated from the creatine resonance at 3.0 ppm. Simulations were performed to examine the effects of frequency drift on the editing efficiency of GABA and co‐edited macromolecules (MM) and of subtraction artifacts on GABA+ quantification. The efficacy of postprocessing frequency correction was also investigated. Results Gradient‐induced frequency drifts affect GABA+ quantification for at least 30 min after imaging. Average frequency drift was low in control sessions and as high as −2 Hz/min after fMRI. Uncorrected frequency drift has an approximately linear effect on GABA+ measurements with a −10 Hz drift resulting in a 16% decrease in GABA+, primarily due to subtraction artifacts. Conclusion Imaging acquisitions with high gradient duty cycles can impact subsequent GABA+ measurements. Postprocessing can address subtraction artifacts, but not changes in editing efficiency or GABA:MM signal ratios; therefore, protocol design should avoid intensive gradient sequences before edited MRS Magn Reson Med 72:941–948, 2014. © 2013 Wiley Periodicals, Inc.