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Observation of coupled 1 H metabolite resonances at long TE
Author(s) -
Soher Brian J.,
Pattany Pradip M.,
Matson Gerald B.,
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.20491
Subject(s) - multiplet , metabolite , spectral line , chemistry , nuclear magnetic resonance , pulse sequence , resonance (particle physics) , singlet state , analytical chemistry (journal) , physics , atomic physics , chromatography , biochemistry , astronomy , excited state
A PRESS localization 1 H MRS acquisition sequence with a Carr–Purcell train of refocusing pulses (CP‐PRESS) has been implemented using global refocusing “sandwich” pulses. The CP pulse train minimized the effects of J ‐coupled dephasing in metabolites with strongly coupled, multiplet resonance groups as demonstrated in both phantom data and in vivo single‐voxel spectroscopy in normal volunteers. Metabolites with multiplet resonance patterns were maintained with greater signal to noise and a simpler resonance pattern at long echo times. T 2 decay times for metabolites with singlet and multiplet resonances were similar to published values, except for the NAA multiplet at 2.5 ppm, which had a significantly shorter T 2 value (147 ms) than that typically reported for the singlet at 2.01 ppm. Metabolite‐nulled spectra were acquired in normal volunteers to evaluate the effects of CP‐PRESS on baseline signal contributions from residual water, lipids, and macromolecules. The T 2 decay times in four baseline regions in data acquired with the CP‐PRESS sequence showed longer decays than corresponding regions in metabolite‐nulled spectra from a standard PRESS sequence, but were significantly diminished long before the metabolites of interest were gone. The spectral analysis for spectra with longer TE times also showed less variability due the higher metabolite SNR, simpler spectral patterns, and the decreased baseline contributions. Magn Reson Med 53:1283–1287, 2005. © 2005 Wiley‐Liss, Inc.