In vivo ¹H NMR spectroscopy of the human brain at 7 T

TLDR

The study employed ultrashort echo‑time STEAM at 7 T, with precise higher‑order shimming via FASTMAP to reduce J‑modulation and signal loss from short T2 metabolites. Sensitivity gains were demonstrated by single‑shot spectra, direct detection of glucose at 5.23 ppm in 8‑ml volumes, a 9 Hz creatine methyl linewidth, and markedly improved resolution of overlapping J‑coupled multiplets such as glutamine and glutamate, allowing clear identification of metabolites like myo‑inositol and taurine. Published in Magn Reson Med 46:451–456 (2001); © 2001 Wiley‑Liss, Inc.

Abstract

Abstract In vivo 1 H NMR spectra from the human brain were measured at 7 T. Ultrashort echo‐time STEAM was used to minimize J‐modulation and signal attenuation caused by the shorter T 2 of metabolites. Precise adjustment of higher‐order shims, which was achieved with FASTMAP, was crucial to benefit from this high magnetic field. Sensitivity improvements were evident from single‐shot spectra and from the direct detection of glucose at 5.23 ppm in 8‐ml volumes. The linewidth of the creatine methyl resonance was at best 9 Hz. In spite of the increased linewidth of singlet resonances at 7 T, the ability to resolve overlapping multiplets of J‐coupled spin systems, such as glutamine and glutamate, was substantially increased. Characteristic spectral patterns of metabolites, e.g., myo ‐inositol and taurine, were discernible in the in vivo spectra, which facilitated an unambiguous signal assignment. Magn Reson Med 46:451–456, 2001. © 2001 Wiley‐Liss, Inc.