title: High magnetic field water and metabolite proton T1 and T2 relaxation in rat brain in vivo.
abstract: Comprehensive and quantitative measurements of T1 and T2 relaxation times of water, metabolites, and macromolecules in rat brain under similar experimental conditions at three high magnetic field strengths (4.0 T, 9.4 T, and 11.7 T) are presented. Water relaxation showed a highly significant increase (T1) and decrease (T2) with increasing field strength for all nine analyzed brain structures. Similar but less pronounced effects were observed for all metabolites. Macromolecules displayed field-independent T2 relaxation and a strong increase of T1 with field strength. Among other features, these data show that while spectral resolution continues to increase with field strength, the absolute signal-to-noise ratio (SNR) in T1/T2-based anatomical MRI quickly levels off beyond approximately 7 T and may actually decrease at higher magnetic fields.
authors.affiliation: Magnetic Resonance Research Center, Yale University, School of Medicine, New Haven, Connecticut 06520-8043, USA. robin.degraaf@yale.edu
authors.forename: Robin A
authors.initials: RA
authors.lastname: de Graaf
authors.forename: Peter B
authors.initials: PB
authors.lastname: Brown
authors.forename: Scott
authors.initials: S
authors.lastname: McIntyre
authors.forename: Terence W
authors.initials: TW
authors.lastname: Nixon
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Behar
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Rothman
mesh_terms: D000818:Animals; D001834:Body Water / Q000378:metabolism; D001923:Brain Chemistry; D001931:Brain Mapping; D017352:Echo-Planar Imaging; D046911:Macromolecular Substances / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D046911:Macromolecular Substances