title: Fractional anisotropy value by diffusion tensor magnetic resonance imaging as a predictor of cell density and proliferation activity of glioblastomas.
abstract: BACKGROUND
  In vivo, water diffusion displays directionality due to presence of complex microstructural barriers in tissue. The extent of directionality of water diffusion can be expressed as a fractional anisotropy (FA) value using diffusion tensor magnetic resonance imaging (DTI). The FA value has been suggested as an indicator of the cell density of astrocytic tumors. The aim of the present study was to confirm beyond doubt that FA values indicate cell density even when limited in glioblastomas and to determine whether the FA value of a given patient predicts proliferation activity in the individual glioblastoma.
  
  
  METHODS
  We performed DTI in 19 patients with glioblastoma and measured the FA values of tumor and normal brain regions prior to computed tomography-guided stereotactic biopsy. Differences in mean FA value between normal brain regions and glioblastoma lesion were compared. Cell density and MIB-1 indices were examined using tumor specimens obtained from biopsies. Correlation among FA values, cell density, and MIB-1 indices was also evaluated.
  
  
  RESULTS
  The mean FA value significantly differed between normal brain regions and glioblastoma lesions. Positive correlation was observed between FA value and cell density (r = 0.73, P < 0.05) and between FA value and MIB-1 index (r = 0.80, P < 0.05).
  
  
  CONCLUSIONS
  Our results suggest that the FA value of glioblastoma as determined by DTI prior to surgery is a good predictor of cell density and, consequently, proliferation activity.
authors.affiliation: Department of Neurosurgery, Iwate Medicl university, Morioka 020-8505, Japan. tbeppu@iwate-med.ac.jp
authors.forename: Takaaki
authors.initials: T
authors.lastname: Beppu
authors.forename: Takashi
authors.initials: T
authors.lastname: Inoue
authors.forename: Yuji
authors.initials: Y
authors.lastname: Shibata
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Yamada
authors.forename: Akira
authors.initials: A
authors.lastname: Kurose
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Ogasawara
authors.forename: Akira
authors.initials: A
authors.lastname: Ogawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kabasawa
mesh_terms: D000328:Adult; D000368:Aged; D016880:Anisotropy; D001834:Body Water / Q000502:physiology; D001921:Brain / Q000473:pathology / Q000502:physiology / Q000503:physiopathology; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000503:physiopathology*; D049109:Cell Proliferation; D004058:Diffusion; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D005909:Glioblastoma / Q000175:diagnosis* / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis