title: Normalized Apparent Diffusion Coefficient in the Prognostication of Patients with Glioblastoma Multiforme.
abstract: BACKGROUND
  Glioblastoma multiforme (GBM) is known to have poor prognosis, with no available imaging marker that can predict survival at the time of diagnosis. Diffusion weighted images are used in characterisation of cellularity and necrosis of GBM. The purpose of this study was to assess whether pattern or degree of diffusion restriction could help in the prognostication of patients with GBM.
  
  
  METHODS
  We retrospectively analyzed 84 consecutive patients with confirmed GBM on biopsy or resection. The study was approved by the institutional ethics committee. The total volume of the tumor and total volume of tumor showing restricted diffusion were calculated. The lowest Apparent Diffusion Coefficient (ADC) in the region of the tumor and in the contralateral Normal Appearing White Matter were calculated in order to calculate the nADC. Treatment and follow-up data in these patients were recorded. Multivariate analsysis was completed to determine significant correlations between different variables and the survival of these patients.
  
  
  RESULTS
  Patient survival was significantly related to the age of the patient (p<0.0001; 95% CI-1.022-1.043) and the nADC value (p=0.014; 95% CI-0.269-0.860) in the tumor. The correlation coefficients of age and nADC with survival were -0.335 (p=0.002) and 0.390 (p<0.001), respectively. Kaplan Meier survival function, grouped by normalized Apparent Diffusion Coefficient cut off value of 0.75, was significant (p=0.007).
  
  
  CONCLUSIONS
  The survival of patients with GBM had small, but significant, correlations with the patient's age and nADC within the tumor.
authors.affiliation: 1Department of Diagnostic Imaging,Division of Neuroradiology,Dalhousie University,Halifax.
authors.forename: Jai Jai Shiva
authors.initials: JJ
authors.lastname: Shankar
authors.affiliation: 1Department of Diagnostic Imaging,Division of Neuroradiology,Dalhousie University,Halifax.
authors.forename: Adil
authors.initials: A
authors.lastname: Bata
authors.affiliation: 2Interdisciplinary research team,IWK,Division of Neurosurgery,Dalhousie University,Halifax.
authors.forename: Krista
authors.initials: K
authors.lastname: Ritchie
authors.affiliation: 3Department of Surgery,Division of Neurosurgery,Dalhousie University,Halifax.
authors.forename: Andrea
authors.initials: A
authors.lastname: Hebb
authors.affiliation: 3Department of Surgery,Division of Neurosurgery,Dalhousie University,Halifax.
authors.forename: Simon
authors.initials: S
authors.lastname: Walling
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001932:Brain Neoplasms / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D005909:Glioblastoma / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D016019:Survival Analysis; D055815:Young Adult
keywords: Apparent Diffusion Coefficient; Diffusion weighted imaging; Glioblastoma Multiforme; Normalized ADC