title: Diffusion-tensor imaging for glioma grading at 3-T magnetic resonance imaging: analysis of fractional anisotropy and mean diffusivity.
abstract: OBJECTIVE
  To retrospectively determine whether fractional anisotropy (FA) or mean diffusivity (MD) value at 3-T diffusion-tensor imaging is different between low- and high-grade gliomas and may be useful for glioma grading.
  
  
  METHODS
  Review board approval was obtained, and informed consent was waived. Diffusion-tensor imaging was performed in 27 patients with surgically proved gliomas (19 high-grade and 8 low-grade gliomas). Fractional anisotropy and MD values were measured in 3 regions; peritumoral edema, and enhancing and nonenhancing tumor regions. We compared mean FA and MD values of nonenhancing tumor regions between low- and high-grade gliomas and compared the FA and MD values among the 3 mentioned regions in high-grade gliomas. The relationship between FA and MD values of tumors was also investigated. Statistical analysis was performed using the Student t test and Pearson correlation coefficients.
  
  
  RESULTS
  In the nonenhancing regions of tumors, FA ratios were not significantly different between low- and high-grade gliomas (0.472 and 0.701, P = 0.075), but MD ratios were significantly lower in high-grade gliomas (1.899 and 1.23, P < 0.001). In high-grade gliomas, enhancing tumors showed a tendency toward a lower FA ratio than nonenhancing tumors (P = 0.034), but FA values or ratios of peritumoral edema were not significantly different from those of enhancing or nonenhancing tumor. No strong relationship was found between FA and MD values.
  
  
  CONCLUSIONS
  Fractional anisotropy values of low- and high-grade gliomas were not significantly different. However, MD values of nonenhancing low-grade gliomas were significantly higher than those of nonenhancing high-grade gliomas, which will be useful for the grading of nonenhancing infiltrative gliomas.
authors: Department of Radiology and Institute of Radiation Medicine, Seoul National University College of Medicine, Clinical Research Institute, Seoul National University Hospital, Seoul, Korea.
authors: Ho Yun
authors: HY
authors: Lee
authors: Dong Gyu
authors: DG
authors: Na
authors: In-Chan
authors: IC
authors: Song
authors: Dong Hoon
authors: DH
authors: Lee
authors: Hyung Suk
authors: HS
authors: Seo
authors: Ji-hoon
authors: JH
authors: Kim
authors: Kee-Hyun
authors: KH
authors: Chang
mesh_terms: D000328:Adult; D000368:Aged; D016880:Anisotropy; D001921:Brain / Q000473:pathology; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000473:pathology; D003287:Contrast Media / Q000008:administration & dosage; D004058:Diffusion; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D019786:Gadolinium DTPA; D005910:Glioma / Q000175:diagnosis* / Q000473:pathology; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA