Noninvasive quantification of human brain ascorbate concentration using 1H NMR spectroscopy at 7 T.
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 micromol/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 micromol/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.
Terpstra
Melissa
M
Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN 55455, USA. melissa@cmrr.umn.edu
Ugurbil
Kamil
K
Tkac
Ivan
I
D000328:Adult; D001205:Ascorbic Acid / Q000032:analysis* / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D013997:Time Factors
D001205:Ascorbic Acid