Resolution Improvements in in Vivo 1H NMR Spectra with Increased Magnetic Field Strength

Rolf Gruetter, Sally A. Weisdorf, Vasantham Rajanayagan, Melissa Terpstra, Hellmut Merkle, Charles L. Truwit, Michael Garwood, Scott Nyberg, Kâmil Uǧurbil

Research output: Contribution to journalArticle

156 Scopus citations

Abstract

The measurement of cerebral metabolites using highly homologous localization techniques and similar shimming methods was performed in the human brain at 1.5 and 4 T as well as in the dog and rat brain at 9.4 T. In rat brain, improved resolution was achieved by shimming all first- and second-order shim coils using a fully adiabatic FASTMAP sequence. The spectra showed a clear improvement in spectral resolution for all metabolite resonances with increased field strength. Changes in cerebral glutamine content were clearly observed at 4 T compared to 1.5 T in patients with hepatic encephalopathy. At 9.4 T, glutamine H4 at 2.46 ppm was fully resolved from glutamate H4 at 2.37 ppm, as was the potential resonance from γ-amino-butyric acid at 2.30 ppm and N-acetyl-aspartyl-glutamate at 2.05 ppm. Singlet linewidths were found to be as low as 6 Hz (0.015 ppm) at 9.4 T, indicating a substantial decrease in ppm linewidth with field strength. Furthermore, the methylene peak of creatine was partially resolved from phosphocreatine, indicating a close to 1:1 relationship in gray matter. We conclude that increasing the magnetic field strength increases spectral resolution also for 1H NMR, which can lead to more than linear sensitivity gains.

Original languageEnglish (US)
Pages (from-to)260-264
Number of pages5
JournalJournal of Magnetic Resonance
Volume135
Issue number1
DOIs
StatePublished - Jan 1 1998

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Keywords

  • H NMR
  • Brain
  • in vivo
  • Magnetic field
  • Resolution

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Nuclear and High Energy Physics
  • Condensed Matter Physics

Cite this

Gruetter, R., Weisdorf, S. A., Rajanayagan, V., Terpstra, M., Merkle, H., Truwit, C. L., Garwood, M., Nyberg, S., & Uǧurbil, K. (1998). Resolution Improvements in in Vivo 1H NMR Spectra with Increased Magnetic Field Strength. Journal of Magnetic Resonance, 135(1), 260-264. https://doi.org/10.1006/jmre.1998.1542