title: MRI grading versus histology: predicting survival of World Health Organization grade II-IV astrocytomas.
abstract: OBJECTIVE
  Histologic grading of intracranial astrocytomas is affected by sampling error and substantial inter- and intraobserver variability. We proposed that incorporating MR imaging into grading will predict patient survival more accurately than histopathology alone.
  
  
  METHODS
  Patients with a new diagnosis of World Health Organization grades II-IV astrocytoma or mixed oligoastrocytoma diagnosed between September 2007 and December 2010 were identified. Two hundred forty-five patients met the inclusion criteria. Preoperative MRIs were independently reviewed by 2 readers blinded to the histologic grade, and an MR imaging grade was given. The MR imaging and histopathologic grades were compared with patient survival.
  
  
  RESULTS
  Patients with grade II or III astrocytomas on histology but evidence of necrosis on MR imaging (consistent with a grade IV tumor) had significantly worse survival than patients with the same histology but no evidence of necrosis on MR imaging (P = .002 for grade II histology and P = .029 for grade III). Their survival was not significantly different from that in patients with grade IV tumors on histology (P = .164 and P = .385, respectively); this outcome suggests that all or most are likely to have truly been grade IV tumors. MR imaging evidence of necrosis was less frequent in grade II and III oligoastrocytomas, preventing adequate subgroup analysis.
  
  
  CONCLUSIONS
  MR imaging can improve grading of intracranial astrocytomas by identifying patients suspected of being undergraded by histology, with high interobserver agreement. This finding has the potential to optimize patient management, for example, by encouraging more aggressive treatment earlier in the patient's course.
authors.affiliation: From the Department of Cancer Imaging (A.L.), Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia arian.lasocki@petermac.org.
authors.forename: A
authors.initials: A
authors.lastname: Lasocki
authors.affiliation: Departments of Pathology (A.T.).
authors.forename: A
authors.initials: A
authors.lastname: Tsui
authors.affiliation: Melbourne EpiCentre (M.A.T.), Department of Medicine, The University of Melbourne and The Royal Melbourne Hospital, Parkville, Victoria, Australia.
authors.forename: M A
authors.initials: MA
authors.lastname: Tacey
authors.affiliation: Neurosurgery (K.J.D.).
authors.forename: K J
authors.initials: KJ
authors.lastname: Drummond
authors.affiliation: Medical Oncology (K.M.F.).
authors.forename: K M
authors.initials: KM
authors.lastname: Field
authors.affiliation: Radiology (F.G.), The Royal Melbourne Hospital, Parkville, Victoria, Australia.
authors.forename: F
authors.initials: F
authors.lastname: Gaillard
mesh_terms: D000328:Adult; D000368:Aged; D001254:Astrocytoma / Q000401:mortality / Q000473:pathology*; D001932:Brain Neoplasms / Q000401:mortality / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading / Q000379:methods*; D059906:Neuroimaging / Q000379:methods*; D015588:Observer Variation; D014944:World Health Organization
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