title: Field dependence study of in vivo brain (31) P MRS up to 16.4 T.
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.
authors: Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, Minneapolis, MN, USA.
authors: Ming
authors: M
authors: Lu
authors: Wei
authors: W
authors: Chen
authors: Xiao-Hong
authors: XH
authors: Zhu
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D057054:Molecular Imaging / Q000379:methods; D010725:Phosphocreatine / Q000378:metabolism*; D010758:Phosphorus / Q000032:analysis / Q000493:pharmacokinetics*; D011829:Radiation Dosage; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014018:Tissue Distribution
chemical_list: D010725:Phosphocreatine; D010758:Phosphorus; D000255:Adenosine Triphosphate
keywords: 31P MRS; NMR sensitivity; high/ultrahigh field; linewidth; relaxation time