title: Reproducibility of in vivo metabolite quantification with proton magnetic resonance spectroscopic imaging.
abstract: OBJECTIVE
  To investigate intra- and interscanner in vivo reproducibility of brain metabolite quantification using 1H magnetic resonance spectroscopic imaging (1H-MRSI) (PRESS localization, TE = 30 msec, voxel volume = 2.3 mL) and the linear combination model (LCModel).
  
  
  METHODS
  One subject had a total of nine scans on three occasions at a single site, and three subjects had single scans at two sites. Coefficients of variation (CVs) were estimated using different statistical models applied to intra- and interscanner data; therefore, only qualitative comparisons may be made between results.
  
  
  RESULTS
  CV (intra-/interscanner) for metabolite quantifications were choline, 12.3%/10.1%; creatine, 9.9%/10.6%; glutamate + glutamine, 15.8%/13.6%; myo-inositol, 18.5%/14.7%; and N-acetyl-aspartate + N-acetyl-aspartyl-glutamate, 6.1%/7.0%. Overall, total intra- and intersubject variability was greater than intra- and interscanner variability.
  
  
  CONCLUSIONS
  When quantifying metabolic concentrations using the methods employed in this study, biological factors contribute a greater proportion to measurement variability than measurement errors. Using this technique, intra- and intersite measurement errors are of the same order.
authors.affiliation: NMR Research Unit, Institute of Neurology, University College London, Queen Square, London, UK. d.chard@ion.ucl.ac.uk
authors.forename: Declan T
authors.initials: DT
authors.lastname: Chard
authors.forename: Mary A
authors.initials: MA
authors.lastname: McLean
authors.forename: Geoffrey J M
authors.initials: GJ
authors.lastname: Parker
authors.forename: David G
authors.initials: DG
authors.lastname: MacManus
authors.forename: David H
authors.initials: DH
authors.lastname: Miller
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000378:metabolism; D000704:Analysis of Variance; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D002794:Choline / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D005260:Female; D006801:Humans; D007294:Inositol / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D011522:Protons
chemical_list: D000596:Amino Acids; D011522:Protons; D001224:Aspartic Acid; D007294:Inositol; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline