title: Repeatability of edited lactate and other metabolites in astrocytoma at 3T.
abstract: OBJECTIVE
  To assess the repeatability of measurement of lactate and other metabolites in tumors using magnetic resonance spectroscopy (MRS).
  
  
  METHODS
  MRS with spectral editing for lactate was performed on 10 patients with astrocytoma (two Grade III, eight Grade IV) using an 8-channel receive coil at 3T. Lactate, lipid, choline, creatine, and N-acetyl aspartate (NAA) signals were measured in regions of tumor and contralateral white matter. Metabolites were quantified relative to unsuppressed water using LCModel fitting software.
  
  
  RESULTS
  The within-patient coefficients of variation were ≈16% (tumor lactate), 6%-8% (tumor choline and contralateral choline, creatine, and NAA), and 22% (tumor lipid). As expected due to their low concentration in normal tissue, lactate and lipid were not reliably detected in white matter but were found at high levels in most tumors. NAA and creatine were lower in tumors than in normal white matter, and choline varied between above- and below-normal values. No consistent short-term variation in metabolite levels was observed, despite differences in the time elapsed since administration of contrast agent.
  
  
  CONCLUSIONS
  MRS appears repeatable enough to provide longitudinal measures of metabolite content in tumors and contralateral tissue in the brain in vivo.
authors.affiliation: Cancer Research UK Cambridge Research Institute, Li Ka Shing Centre, Cambridge, UK. Mary.McLean@cancer.org.uk
authors.forename: Mary A
authors.initials: MA
authors.lastname: McLean
authors.forename: Amy
authors.initials: A
authors.lastname: Sun
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Bradstreet
authors.forename: Andrea K
authors.initials: AK
authors.lastname: Schaeffer
authors.forename: Haiying
authors.initials: H
authors.lastname: Liu
authors.forename: Robert
authors.initials: R
authors.lastname: Iannone
authors.forename: Gary
authors.initials: G
authors.lastname: Herman
authors.forename: Radha A
authors.initials: RA
authors.lastname: Railkar
authors.forename: Ilse
authors.initials: I
authors.lastname: Joubert
authors.forename: Jonathan H
authors.initials: JH
authors.lastname: Gillard
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Price
authors.forename: John R
authors.initials: JR
authors.lastname: Griffiths
mesh_terms: D001254:Astrocytoma / Q000175:diagnosis / Q000378:metabolism*; D014408:Biomarkers, Tumor / Q000032:analysis*; D001932:Brain Neoplasms / Q000175:diagnosis / Q000378:metabolism*; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000032:analysis* / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D014408:Biomarkers, Tumor; D019344:Lactic Acid