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Novel strategy for cerebral 13 C MRS using very low RF power for proton decoupling
Author(s) -
Li Shizhe,
Yang Jehoon,
Shen Jun
Publication year - 2007
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.21148
Subject(s) - decoupling (probability) , scalar (mathematics) , glutamine , chemistry , in vivo , nuclear magnetic resonance , amide , physics , biochemistry , mathematics , biology , amino acid , geometry , microbiology and biotechnology , control engineering , engineering
One of the major difficulties of in vivo 13 C MRS is the need to decouple the large, one‐bond, 1 H‐ 13 C scalar couplings in order to obtain useful signal‐to‐noise ratios (SNRs) and spectral resolution at magnetic field strengths that are accessible to clinical studies. In this report a new strategy for in vivo cerebral 13 C MRS is proposed. We realized that the turnover kinetics of glutamate (Glu) C5 from exogenous [2‐ 13 C]glucose (Glc) is identical to that of Glu C4 from exogenous [1‐ 13 C]Glc. The carboxylic/amide carbons are only coupled to protons via very weak long‐range 1 H‐ 13 C scalar couplings. As such, they can be effectively decoupled at very low RF power. Therefore, decoupling of the large 1 H‐ 13 C scalar couplings can be avoided by the use of [2‐ 13 C]Glc. An additional advantage of this strategy is the lack of contamination from subcutaneous lipids because there are no overlapping fat signals in the vicinity of the Glu C5 and glutamine (Gln) C5 peaks. The feasibility of this strategy was demonstrated using 13 C MRS on rhesus monkey brains at 4.7T. Magn Reson Med 57:265–271, 2007. © 2007 Wiley‐Liss, Inc.