title: Differentiating diffuse World Health Organization grade II and IV astrocytomas with ex vivo magnetic resonance spectroscopy.
abstract: BACKGROUND
  The prognosis and treatment of astrocytomas, which are primary brain tumors, vary depending on the grade of the tumor, necessitating a precise preoperative classification. Magnetic resonance spectroscopy (MRS) provides information about metabolites in tissues and is an emerging noninvasive tool to improve diagnostic accuracy in patients with intracranial neoplasia.
  
  
  OBJECTIVE
  To investigate whether ex vivo MRS could differentiate World Health Organization grade II (A-II) and IV astrocytomas (glioblastomas; GBM) and to correlate MR spectral profiles with clinical parameters.
  
  
  METHODS
  Patients with A-II and GBM (n = 58) scheduled for surgical resection were enrolled. Tumor specimens were collected during surgery and stored in liquid nitrogen before being analyzed with high-resolution magic angle spinning MRS. The tumors were histopathologically classified according to World Health Organization criteria as GBM (n = 48) and A-II (n = 10).
  
  
  RESULTS
  Multivariate analysis of ex vivo proton high-resolution magic angle spinning spectra MRS showed differences in the metabolic profiles of different grades of astrocytomas. A-II had higher levels of glycerophosphocholine and myo-inositol than GBM. The latter had more phosphocholine, glycine, and lipids. We observed a significant metabolic difference between recurrent and nonrecurrent GBM (P < .001). Primary GBM had more phosphocholine than recurrent GBM. A significant correlation (P < .001) between lipid and lactate signals and histologically estimated percentage of necrosis was observed in GBM. Spectral profiles were not correlated with age, survival, or magnetic resonance imaging-defined tumor volume.
  
  
  CONCLUSIONS
  Ex vivo MRS can differentiate astrocytomas based on their metabolic profiles.
authors.affiliation: Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway. muhammad.r.vettukattil@ntnu.no
authors.forename: Riyas
authors.initials: R
authors.lastname: Vettukattil
authors.forename: Michel
authors.initials: M
authors.lastname: Gulati
authors.forename: Torill E
authors.initials: TE
authors.lastname: Sjøbakk
authors.forename: Asgeir S
authors.initials: AS
authors.lastname: Jakola
authors.forename: Nadja A M
authors.initials: NA
authors.lastname: Kvernmo
authors.forename: Sverre H
authors.initials: SH
authors.lastname: Torp
authors.forename: Tone F
authors.initials: TF
authors.lastname: Bathen
authors.forename: Sasha
authors.initials: S
authors.lastname: Gulati
authors.forename: Ingrid S
authors.initials: IS
authors.lastname: Gribbestad
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001224:Aspartic Acid / Q000378:metabolism; D001254:Astrocytoma / Q000145:classification* / Q000175:diagnosis* / Q000235:genetics; D001932:Brain Neoplasms / Q000145:classification* / Q000175:diagnosis* / Q000235:genetics; D002794:Choline / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D005260:Female; D006801:Humans; D007521:Isocitrate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009154:Mutation / Q000235:genetics; D011237:Predictive Value of Tests; D025341:Principal Component Analysis; D012720:Severity of Illness Index; D014944:World Health Organization
chemical_list: D001224:Aspartic Acid; D007521:Isocitrate Dehydrogenase; C543588:IDH1 protein, human; D003401:Creatine; D002794:Choline