title: Association of metabolite concentrations and water diffusivity in normal appearing brain tissue with glioma grade.
abstract: OBJECTIVE
  Studies of brain tumors have identified altered tissue metabolism and water diffusion in MRI normal appearing tissue regions. In this retrospective study the relationship of these imaging measures with tumor grade in gliomas was investigated.
  
  
  METHODS
  MR spectroscopic imaging of whole brain and mean diffusivity (MD) measurements were obtained in subjects with untreated glioma and from normal control subjects. Mean metabolite values for N-acetylaspartate (NAA), total creatine (Cre), and total choline (Cho) were obtained in gray- and white-matter regions for the hemisphere contralateral to the tumor location, and MD values were obtained from contralateral normal-appearing white matter. Analyses tested for differences in mean values between subject groups while accounting for age.
  
  
  RESULTS
  Analysis demonstrated increased NAA/Cre and MD, and decreased Cho/NAA for all tumor grades relative to control values. Differences between tumor grades were also observed for NAA, NAA/Cre, and Cho/NAA. Abnormal values of water diffusion were also observed, but with only a weak association between alterations in diffusion and tissue metabolites.
  
  
  CONCLUSIONS
  This study supports previous observations of altered tissue metabolism and water diffusion in normal-appearing white matter while additionally finding differences of metabolite values in gray matter and an association with tumor grade.
authors.affiliation: Department of Radiology, University of Miami, Florida.
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Maudsley
authors.affiliation: Departments of Radiodiagnosis, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India.
authors.forename: Bhaswati
authors.initials: B
authors.lastname: Roy
authors.affiliation: Departments of Radiodiagnosis, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India.
authors.forename: Rakesh K
authors.initials: RK
authors.lastname: Gupta
authors.affiliation: Department of Radiology, University of Miami, Florida.
authors.forename: Sulaiman
authors.initials: S
authors.lastname: Sheriff
authors.affiliation: Departments of Radiodiagnosis, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India.
authors.forename: Rishi
authors.initials: R
authors.lastname: Awasthi
authors.affiliation: Department of Radiology, Stanford University, California.
authors.forename: Meng
authors.initials: M
authors.lastname: Gu
authors.affiliation: Department of Pathology, Ram Manohar Lohia, Institute of Medical Sciences, Lucknow, India.
authors.forename: Nuzhat
authors.initials: N
authors.lastname: Husain
authors.affiliation: Departments of Radiodiagnosis, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India.
authors.forename: Sudipa
authors.initials: S
authors.lastname: Mohakud
authors.affiliation: Departments of Neurosurgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India.
authors.forename: Sanjay
authors.initials: S
authors.lastname: Behari
authors.affiliation: Department of Radiology, Stanford University, California.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Spielman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001834:Body Water / Q000737:chemistry; D001921:Brain / Q000378:metabolism* / Q000473:pathology*; D001923:Brain Chemistry; D001932:Brain Neoplasms / Q000737:chemistry / Q000378:metabolism* / Q000473:pathology*; D004058:Diffusion; D005260:Female; D005910:Glioma / Q000737:chemistry / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014018:Tissue Distribution; D055815:Young Adult
keywords: 1H MRSI; MRI diffusion; brain; glioma; normal tissue; spectroscopic imaging