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Noninvasive quantification of human brain ascorbate concentration using 1 H NMR spectroscopy at 7 T
Author(s) -
Terpstra Melissa,
Ugurbil Kamil,
Tkac Ivan
Publication year - 2010
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.1423
Subject(s) - homonuclear molecule , echo time , nuclear magnetic resonance , chemistry , nuclear magnetic resonance spectroscopy , analytical chemistry (journal) , dispersion (optics) , spectroscopy , magnetic resonance imaging , chromatography , physics , optics , medicine , quantum mechanics , organic chemistry , molecule , radiology
Ascorbate (Asc, vitamin C) was quantified in the human brain noninvasively using two different 1 H NMR spectroscopy methods: short‐echo time STEAM and MEGA‐PRESS homonuclear editing. Taking advantage of increased sensitivity and chemical shift dispersion at 7 T, Asc was quantified with increased reliability relative to our previous study accomplished at 4 T. Asc concentration quantified from short‐echo time spectra measured from the occipital lobe of eight healthy subjects ([Asc] = 1.1 ± 0.3 µmol/g, mean ± SD) was in excellent agreement with Asc concentration quantified from the same volume of interest using homonuclear editing ([Asc] = 1.2 ± 0.2 µmol/g). This agreement indicates that at 7 T, Asc can be reliably quantified in the human brain simultaneously with 15 other metabolites. Additional advantages of the short‐echo time approach were: shorter measurement time than homonuclear editing and minimal effect of T 2 relaxation on Asc quantification. High magnetic field was also beneficial for Asc quantification with MEGA‐PRESS because increased chemical shift dispersion enabled editing with full efficiency, which resulted in a supra‐linear gain in signal‐to‐noise ratio relative to 4 T. Copyright © 2009 John Wiley & Sons, Ltd.