Brief Article
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World J Radiol. Apr 28, 2011; 3(4): 105-113
Published online Apr 28, 2011. doi: 10.4329/wjr.v3.i4.105
Applications of multi-nuclear magnetic resonance spectroscopy at 7T
Mary C Stephenson, Frances Gunner, Antonio Napolitano, Paul L Greenhaff, Ian A MacDonald, Nadeem Saeed, William Vennart, Susan T Francis, Peter G Morris
Mary C Stephenson, Susan T Francis, Peter G Morris, The Sir Peter Mansfield Magnetic Resonance Centre, School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
Frances Gunner, Paul L Greenhaff, Ian A MacDonald, School of Biomedical Sciences, University of Nottingham Medical School, Nottingham NG7 2UH, United Kingdom
Antonio Napolitano, Academic Radiology, University of Nottingham, Nottingham NG7 2UH, United Kingdom
Nadeem Saeed, William Vennart, Molecular Medicine, Pfizer, Sandwich, Kent CT13 9NJ, United Kingdom
Author contributions: Stephenson MC, Gunner F, Morris PG, Francis ST, Saeed N, MacDonald IA, Greenhaff PL and Vennart W designed the research; Stephenson MC and Gunner F performed the research; Stephenson MC analyzed the data; Napolitano A contributed new analytic tools; Stephenson MC and Morris PG wrote the paper.
Supported by The Haldane-Spearman Consortium for PhD funding for Dr. Gunner F, Swecarb AB for provision of the carbohydrate drink, and Pfizer for funding the 1H Repeatability work. Dr.Stephenson M was supported by the University of Nottingham’s Mansfield Fellowship scheme. 7T work was supported by grant G9900259 from the Medical Research Council; Pfizer and grant G0901321 from the Medical Research Council; The 7 T MR Scanner in Nottingham, was funded by a Joint Infrastructure Fund Grant from the Wellcome Trust UK
Correspondence to: Mary C Stephenson, PhD, The Sir Peter Mansfield Magnetic Resonance Centre, School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom.
Telephone: +44-115-9566881 Fax: +44-115-9515166
Received: October 22, 2010
Revised: April 2, 2011
Accepted: April 9, 2011
Published online: April 28, 2011

AIM: To discuss the advantages of ultra-high field (7T) for 1H and 13C magnetic resonance spectroscopy (MRS) studies of metabolism.

METHODS: Measurements of brain metabolites were made at both 3 and 7T using 1H MRS. Measurements of glycogen and lipids in muscle were measured using 13C and 1H MRS respectively.

RESULTS: In the brain, increased signal-to-noise ratio (SNR) and dispersion allows spectral separation of the amino-acids glutamate, glutamine and γ-aminobutyric acid (GABA), without the need for sophisticated editing sequences. Improved quantification of these metabolites is demonstrated at 7T relative to 3T. SNR was 36% higher, and measurement repeatability (% coefficients of variation) was 4%, 10% and 10% at 7T, vs 8%, 29% and 21% at 3T for glutamate, glutamine and GABA respectively. Measurements at 7T were used to compare metabolite levels in the anterior cingulate cortex (ACC) and insula. Creatine and glutamate levels were found to be significantly higher in the insula compared to the ACC (P < 0.05). In muscle, the increased SNR and spectral resolution at 7T enables interleaved studies of glycogen (13C) and intra-myocellular lipid (IMCL) and extra-myocellular lipid (EMCL) (1H) following exercise and re-feeding. Glycogen levels were significantly decreased following exercise (-28% at 50% VO2 max; -58% at 75% VO2 max). Interestingly, levels of glycogen in the hamstrings followed those in the quadriceps, despite reduce exercise loading. No changes in IMCL and EMCL were found in the study.

CONCLUSION: The demonstrated improvements in brain and muscle MRS measurements at 7T will increase the potential for use in investigating human metabolism and changes due to pathologies.

Keywords: Magnetic resonance spectroscopy, 13C, 1H, 7 Tesla, Glutamate, Glutamine, γ-aminobutyric acid