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NMR Biomed. 2014 Sep;27(9):1135-41. doi: 10.1002/nbm.3167. Epub 2014 Jul 28.

Field dependence study of in vivo brain (31) P MRS up to 16.4 T.

Author information

1
Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, Minneapolis, MN, USA.

Abstract

In vivo (31) P MRS provides a unique tool for studying bioenergetics of living organs. Although its utility has been limited by the relatively low (31) P NMR sensitivity, increasing magnetic field strength (B0 ) could significantly improve the quality and reliability of the (31) P MR spectra for biomedical research. To quantitatively understand the field dependence of in vivo (31) P MRS for brain applications, (31) P NMR sensitivity of phosphocreatine (PCr) in rat brains was measured and compared at 9.4 T and 16.4 T. Additionally, the linewidths and T1 relaxation times of PCr and adenosine triphosphate (ATP) resonances obtained from human and animal brains over a wide B0 range from 4 T, 7 T, and 9.4 T to 16.4 T were examined and their field dependences were quantified. The results indicate an approximate 1.74-fold (31) P signal-to-noise ratio (SNR) gain for PCr at 16.4 T compared with 9.4 T. An approximate power 1.4 dependence of (31) P SNR on B0 was concluded. Substantial improvements in spectral resolution and significantly shortened T1 values of brain PCr and ATP were observed at high/ultrahigh fields, contributing to an additional sensitivity gain and spectral improvement. In summary, the overall findings from this study suggest that in vivo (31) P MRS should greatly benefit from high/ultrahigh fields for noninvasive assessment of altered bioenergetics and metabolic processes associated with brain function and neurological diseases.

KEYWORDS:

31P MRS; NMR sensitivity; high/ultrahigh field; linewidth; relaxation time

PMID:
25070004
PMCID:
PMC4180101
DOI:
10.1002/nbm.3167
[Indexed for MEDLINE]
Free PMC Article

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