title: Histogram analysis of MR imaging-derived cerebral blood volume maps: combined glioma grading and identification of low-grade oligodendroglial subtypes.
abstract: OBJECTIVE
  Inclusion of oligodendroglial tumors may confound the utility of MR based glioma grading. Our aim was, first, to assess retrospectively whether a histogram-analysis method of MR perfusion images may both grade gliomas and differentiate between low-grade oligodendroglial tumors with or without loss of heterozygosity (LOH) on 1p/19q and, second, to assess retrospectively whether low-grade oligodendroglial subtypes can be identified in a population of patients with high-grade and low-grade astrocytic and oligodendroglial tumors.
  
  
  METHODS
  Fifty-two patients (23 women, 29 men; mean age, 52 years; range, 19-78 years) with histologically confirmed gliomas were imaged by using dynamic susceptibility contrast MR imaging at 1.5T. Relative cerebral blood volume (rCBV) maps were created, and 4 neuroradiologists defined the glioma volumes independently. Averaged over the 4 observers, a histogram-analysis method was used to assess the normalized histogram peak height of the glioma rCBV distributions.
  
  
  RESULTS
  Of the 52 patients, 22 had oligodendroglial tumors. The histogram method was able to differentiate high-grade gliomas (HGGs) from low-grade gliomas (LGGs) (Mann-Whitney U test, P < .001) and to identify low-grade oligodendroglial subtypes (P = .009). The corresponding intraclass correlation coefficients were 0.902 and 0.801, respectively. The sensitivity and specificity in terms of differentiating low-grade oligodendroglial tumors without LOH on 1p/19q from the other tumors was 100% (6/6) and 91% (42/46), respectively.
  
  
  CONCLUSIONS
  With histology as a reference, our results suggest that histogram analysis of MR imaging-derived rCBV maps can differentiate HGGs from LGGs as well as low-grade oligodendroglial subtypes with high interobserver agreement. Also, the method was able to identify low-grade oligodendroglial tumors without LOH on 1p/19q in a population of patients with astrocytic and oligodendroglial tumors.
authors.affiliation: Department of Medical Physics, Rikshospitalet University Hospital, Oslo, Norway. kyrre.eeg.emblem@rikshospitalet.no
authors.forename: K E
authors.initials: KE
authors.lastname: Emblem
authors.forename: D
authors.initials: D
authors.lastname: Scheie
authors.forename: P
authors.initials: P
authors.lastname: Due-Tonnessen
authors.forename: B
authors.initials: B
authors.lastname: Nedregaard
authors.forename: T
authors.initials: T
authors.lastname: Nome
authors.forename: J K
authors.initials: JK
authors.lastname: Hald
authors.forename: K
authors.initials: K
authors.lastname: Beiske
authors.forename: T R
authors.initials: TR
authors.lastname: Meling
authors.forename: A
authors.initials: A
authors.lastname: Bjornerud
mesh_terms: D000328:Adult; D000368:Aged; D001810:Blood Volume / Q000502:physiology*; D001932:Brain Neoplasms / Q000098:blood supply* / Q000175:diagnosis / Q000235:genetics / Q000473:pathology; D003937:Diagnosis, Differential; D005260:Female; D005910:Glioma / Q000098:blood supply* / Q000175:diagnosis / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D019656:Loss of Heterozygosity; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009837:Oligodendroglioma / Q000098:blood supply* / Q000175:diagnosis / Q000235:genetics / Q000473:pathology; D016133:Polymerase Chain Reaction; D011379:Prognosis; D012680:Sensitivity and Specificity