title: Comparison of magnetic resonance spectroscopy and perfusion-weighted imaging in presurgical grading of oligodendroglial tumors.
abstract: OBJECTIVE
  Oligodendroglial tumors form an uncommon, but distinct, subgroup of gliomas with longer survival, better treatment response, and characteristic genetic alterations. Noninvasive grading of oligodendroglial tumors using functional and metabolic magnetic resonance imaging may be helpful in guiding the treatment approach and predicting malignant transformation of these tumors. We used perfusion-weighted magnetic resonance imaging and proton magnetic resonance spectroscopic imaging (MRSI) to predict the oligodendroglioma grade.
  
  
  METHODS
  Twenty-four patients with pathologically confirmed oligodendrogliomas underwent dynamic contrast-enhanced perfusion-weighted magnetic resonance imaging and/or proton MRSI before surgery. We assessed the ability of tumor contrast enhancement, normalized cerebral blood volume, normalized choline, and the presence of either lactate or lipid metabolites to correctly predict the World Health Organization tumor grade. The accuracy of tumor grading using each method was also compared.
  
  
  RESULTS
  Tumor contrast enhancement (P = 0.069) and normalized cerebral blood volume (P = 0.181) were not significantly different between low and high-grade oligodendrogliomas. The MRSI measurement of normalized choline was significantly higher in high-grade (2.82 +/- 0.64) than in low-grade (1.62 +/- 0.46) oligodendrogliomas (P < 0.001), and the presence of lactate or lipid metabolites also correctly predicted high-grade tumors (P = 0.014). The maximum accuracy of contrast enhancement, normalized cerebral blood volume, normalized choline, and lactate or lipid metabolites in grading oligodendroglioma was 71, 83, 90, and 85%, respectively.
  
  
  CONCLUSIONS
  MRSI measurements are more accurate than perfusion-weighted magnetic resonance imaging or conventional contrast enhancement in differentiating oligodendroglial tumor grade. In these inherently vascular tumors, metabolic measurements of mitosis and necrosis may be better than measures of neovascularity in presurgical grading.
authors.affiliation: Department of Neuroradiology, National Neuroscience Institute, Singapore, Singapore.
authors.forename: Maosheng
authors.initials: M
authors.lastname: Xu
authors.forename: Siew Ju
authors.initials: SJ
authors.lastname: See
authors.forename: Wai Hoe
authors.initials: WH
authors.lastname: Ng
authors.forename: Earnest
authors.initials: E
authors.lastname: Arul
authors.forename: Michael F
authors.initials: MF
authors.lastname: Back
authors.forename: Tseng Tsai
authors.initials: TT
authors.lastname: Yeo
authors.forename: C C Tchoyoson
authors.initials: CC
authors.lastname: Lim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000601:surgery*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D009837:Oligodendroglioma / Q000175:diagnosis* / Q000601:surgery*; D011300:Preoperative Care; D015203:Reproducibility of Results; D012189:Retrospective Studies