Investigating brain metabolism at high fields using localized 13C NMR spectroscopy without 1H decoupling

Most in vivo 13C NMR spectroscopy studies in the brain have been performed using 1H decoupling during acquisition. Decoupling imposes significant constraints on the experimental setup (particularly for human studies at high magnetic field) in order to stay within safety limits for power deposition....

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Bibliographic Details
Published in:Magnetic resonance in medicine 2006-02, Vol.55 (2), p.279-286
Main Authors: Deelchand, Dinesh Kumar, Uğurbil, Kâmil, Henry, Pierre-Gilles
Format: Article
Language:English
Subjects:
13C NMR spectroscopy
Animals
Aspartic Acid - metabolism
Brain - metabolism
Carbon Isotopes
decoupling
Feasibility Studies
Glutamic Acid - metabolism
Glutamine - metabolism
LCModel
long-range couplings
Magnetic Resonance Spectroscopy - methods
Monte Carlo Method
Rats
Signal Processing, Computer-Assisted
specific absorption rate
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Summary:Most in vivo 13C NMR spectroscopy studies in the brain have been performed using 1H decoupling during acquisition. Decoupling imposes significant constraints on the experimental setup (particularly for human studies at high magnetic field) in order to stay within safety limits for power deposition. We show here that incorporation of the 13C label from 13C‐labeled glucose into brain amino acids can be monitored accurately using localized 13C NMR spectroscopy without the application of 1H decoupling. Using LCModel quantification with prior knowledge of one‐bond and multiple‐bond JCH coupling constants, the uncertainty on metabolites concentrations was only 35% to 91% higher (depending on the carbon resonance of interest) in undecoupled spectra compared to decoupled spectra in the rat brain at 9.4 Tesla. Although less sensitive, 13C NMR without decoupling dramatically reduces experimental constraints on coil setup and pulse sequence design required to keep power deposition within safety guidelines. This opens the prospect of safely measuring 13C NMR spectra in humans at varied brain locations (not only the occipital lobe) and at very high magnetic fields above 4 Tesla. Magn Reson Med, 2006. © 2005 Wiley‐Liss, Inc.
ISSN:0740-3194
1522-2594
DOI:10.1002/mrm.20756