H-1-[C-13] NMR Spectroscopy of the Rat Brain During Infusion of [2-C-13] Acetate at 14.1 T

Full signal intensity H-1-[C-13] NMR spectroscopy, combining a preceding C-13-editing block based on an inversion BISEP (B-1-insensitive spectral editing pulse) with a spin-echo coherence-based localization, was developed and implemented at 14.1 T. C-13 editing of the proposed scheme was achieved by turning on and off the C-13 adiabatic full passage in the C-13-editing block to prepare inverted and noninverted C-13-coupled H-1 coherences along the longitudinal axis prior to localization. The novel H-1-[C-13] NMR approach was applied in vivo under infusion of the glia-specific substrate [2-C-13] acetate. Besides a similar to 50% improvement in sensitivity, spectral dispersion was enhanced at 14.1 T, especially for J-coupled metabolites such as glutamate and glutamine. A more distinct spectral structure at 1.9-2.2 ppm(parts per million) was observed, e.g., glutamate C3 showed a doublet pattern in both simulated H-1 spectrum and in vivo C-13-edited H-1 NMR spectra. Besides C-13 time courses of glutamate C4 and glutamine C4, the time courses of glutamate C3 and glutamine C3 obtained by H-1-[C-13] NMR spectroscopy were reported for the first time. Such capability should greatly improve the ability to study neuronglial metabolism using H-1-observed C-13-edited NMR spectroscopy. Magn Reson Med 64:334-340, 2010. (C) 2010 Wiley-Liss, Inc