title: 1H metabolite relaxation times at 3.0 tesla: Measurements of T1 and T2 values in normal brain and determination of regional differences in transverse relaxation.
abstract: OBJECTIVE
  To measure 1H relaxation times of cerebral metabolites at 3 T and to investigate regional variations within the brain.
  
  
  METHODS
  Investigations were performed on a 3.0-T clinical whole-body magnetic resonance (MR) system. T2 relaxation times of N-acetyl aspartate (NAA), total creatine (tCr), and choline compounds (Cho) were measured in six brain regions of 42 healthy subjects. T1 relaxation times of these metabolites and of myo-inositol (Ins) were determined in occipital white matter (WM), the frontal lobe, and the motor cortex of 10 subjects.
  
  
  RESULTS
  T2 values of all metabolites were markedly reduced with respect to 1.5 T in all investigated regions. T2 of NAA was significantly (P < 0.001) shorter in the motor cortex (247 +/- 13 msec) than in occipital WM (301 +/- 18 msec). T2 of the tCr methyl resonance showed a corresponding yet less pronounced decrease (162 +/- 16 msec vs. 178 +/- 9 msec, P = 0.021). Even lower T2 values for all metabolites were measured in the basal ganglia. Metabolite T1 relaxation times at 3.0 T were not significantly different from the values at 1.5 T.
  
  
  CONCLUSIONS
  Transverse relaxation times of the investigated cerebral metabolites exhibit an inverse proportionality to magnetic field strength, and especially T2 of NAA shows distinct regional variations at 3 T. These can be attributed to differences in relative WM/gray matter (GM) contents and to local paramagnetism.
authors.affiliation: Department of Radiology, University of Bonn, Bonn, Germany. traeber@uni-bonn.de
authors.forename: Frank
authors.initials: F
authors.lastname: Träber
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Block
authors.forename: Rolf
authors.initials: R
authors.lastname: Lamerichs
authors.forename: Jürgen
authors.initials: J
authors.lastname: Gieseke
authors.forename: Hans H
authors.initials: HH
authors.lastname: Schild
mesh_terms: D000328:Adult; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D002794:Choline / Q000378:metabolism; D003404:Creatinine / Q000378:metabolism; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D011522:Protons
chemical_list: D011522:Protons; D001224:Aspartic Acid; C000179:N-acetylaspartate; D003404:Creatinine; D002794:Choline