title: Metabolic changes in the normal ageing brain: consistent findings from short and long echo time proton spectroscopy.
abstract: OBJECTIVE
  Sixty three healthy subjects were measured to assess dependence of brain metabolites on age using short- and long echo time spectroscopy in different brain regions.
  
  
  METHODS
  Younger and elderly humans were measured with long echo time (TE=135ms) 3D-MR-spectroscopic imaging (MRSI) (10 subjects) and with ultra-short echo (TE=11ms) time 2D-MRSI (7 subjects). In addition, results from single voxel (1)H-spectroscopy (TE=20ms) of two cohorts of 46 healthy subjects were retrospectively correlated with age.
  
  
  RESULTS
  3D-MR SI revealed reduced NAA/Cr in the older group in the frontal lobe (-22%; p<0.01), parietal lobe (-28%; p<0.01) and semiovale (-9%; p<0.01) compared to the younger group. Cho/Cr was elevated in the semiovale (+35%; p<0.01) and in the n. lentiformis (+42%; p<0.01) in the older group. NAA/Cho was reduced in all regions measured, except the thalamus, in the older group compared to the younger group (from -21 to -49%; p<0.01). 2D-MRSI revealed decreased total NAA (-3.1% per decade; p<0.01) and NAA/Cr (-3.8% per decade; p<0.01), increased total Cho (+3.6% per decade; p<0.01) and Cho/Cr (+4.6% per decade; p<0.01) and increased total myo-Inositol (mI, +4.7% per decade; p<0.01) and mI/Cr (+5.4% per decade; p<0.01) and decreased NAA/Cho (-8% per decade; p<0.01) in semiovale WM. Results from single voxel spectroscopy revealed a significantly negative correlation of NAA/Cho in frontal (-13% per decade; p<0.01) and in temporal lobe (-7.4% per decade; p<0.01) as well as increased total Cr (10% per decade; p<0.01) in frontal lobe. Other results from single voxel measurements were not significant, but trends were comparable to that from multivoxel spectroscopy.
  
  
  CONCLUSIONS
  Age-related changes measured with long echo time and short echo time 1H-MRS were comparable and cannot, therefore, be caused by different T2 relaxation times in young and old subjects, as suggested previously.
authors.affiliation: Department of Diagnostic Radiology, Medical University of Vienna, 1090 Vienna, Austria.
authors.forename: S
authors.initials: S
authors.lastname: Gruber
authors.forename: K
authors.initials: K
authors.lastname: Pinker
authors.forename: F
authors.initials: F
authors.lastname: Riederer
authors.forename: M
authors.initials: M
authors.lastname: Chmelík
authors.forename: A
authors.initials: A
authors.lastname: Stadlbauer
authors.forename: M
authors.initials: M
authors.lastname: Bittsanský
authors.forename: V
authors.initials: V
authors.lastname: Mlynárik
authors.forename: R
authors.initials: R
authors.lastname: Frey
authors.forename: W
authors.initials: W
authors.lastname: Serles
authors.forename: O
authors.initials: O
authors.lastname: Bodamer
authors.forename: E
authors.initials: E
authors.lastname: Moser
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism*; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D002794:Choline / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
chemical_list: D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline