title: Quantitative characterization of the imaging limits of diffuse low-grade oligodendrogliomas.
abstract: BACKGROUND
  Supratentorial diffuse low-grade gliomas in adults extend beyond maximal visible MRI-defined abnormalities, and a gap exists between the imaging signal changes and the actual tumor margins. Direct quantitative comparisons between imaging and histological analyses are lacking to date. However, they are of the utmost importance if one wishes to develop realistic models for diffuse glioma growth.
  
  
  METHODS
  In this study, we quantitatively compared the cell concentration and the edema fraction from human histological biopsy samples (BSs) performed inside and outside imaging abnormalities during serial imaging-based stereotactic biopsy of diffuse low-grade gliomas.
  
  
  RESULTS
  The cell concentration was significantly higher in BSs located inside (1189 ± 378 cell/mm(2)) than outside (740 ± 124 cell/mm(2)) MRI-defined abnormalities (P = .0003). The edema fraction was significantly higher in BSs located inside (mean, 45% ± 23%) than outside (mean, 5 %± 9%) MRI-defined abnormalities (P < .0001). At borders of the MRI-defined abnormalities, 20% of the tissue surface area was occupied by edema and only 3% by tumor cells. The cycling cell concentration was significantly higher in BSs located inside (10 ± 12 cell/mm(2)), compared with outside (0.5 ± 0.9 cell/mm(2)), MRI-defined abnormalities (P = .0001).
  
  
  CONCLUSIONS
  We showed that the margins of T2-weighted signal changes are mainly correlated with the edema fraction. In 62.5% of patients, the cycling tumor cell fraction (defined as the ratio of the cycling tumor cell concentration to the total number of tumor cells) was higher at the limits of the MRI-defined abnormalities than closer to the center of the tumor. In the remaining patients, the cycling tumor cell fraction increased towards the center of the tumor.
authors.affiliation: Corresponding Author: Mathilde Badoual, Laboratoire IMNC, Campus Universitaire d'Orsay, bat 440, 91405, Orsay, France. badoual@imnc.in2p3.fr.
authors.forename: Chloé
authors.initials: C
authors.lastname: Gerin
authors.forename: Johan
authors.initials: J
authors.lastname: Pallud
authors.forename: Christophe
authors.initials: C
authors.lastname: Deroulers
authors.forename: Pascale
authors.initials: P
authors.lastname: Varlet
authors.forename: Catherine
authors.initials: C
authors.lastname: Oppenheim
authors.forename: Francois-Xavier
authors.initials: FX
authors.lastname: Roux
authors.forename: Fabrice
authors.initials: F
authors.lastname: Chrétien
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Thomas
authors.forename: Basile
authors.initials: B
authors.lastname: Grammaticos
authors.forename: Mathilde
authors.initials: M
authors.lastname: Badoual
mesh_terms: D000328:Adult; D001706:Biopsy; D001929:Brain Edema / Q000175:diagnosis*; D001932:Brain Neoplasms / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007089:Image Enhancement; D007124:Immunoenzyme Techniques; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009837:Oligodendroglioma / Q000175:diagnosis*; D011379:Prognosis; D012189:Retrospective Studies; D013223:Statistics as Topic
keywords: edema; gliomas; histology; magnetic resonance imaging; quantification