title: Gliomas: application of cumulative histogram analysis of normalized cerebral blood volume on 3 T MRI to tumor grading.
abstract: BACKGROUND
  Glioma grading assumes significant importance in that low- and high-grade gliomas display different prognoses and are treated with dissimilar therapeutic strategies. The objective of our study was to retrospectively assess the usefulness of a cumulative normalized cerebral blood volume (nCBV) histogram for glioma grading based on 3 T MRI.
  
  
  METHODS
  From February 2010 to April 2012, 63 patients with astrocytic tumors underwent 3 T MRI with dynamic susceptibility contrast perfusion-weighted imaging. Regions of interest containing the entire tumor volume were drawn on every section of the co-registered relative CBV (rCBV) maps and T2-weighted images. The percentile values from the cumulative nCBV histograms and the other histogram parameters were correlated with tumor grades. Cochran's Q test and the McNemar test were used to compare the diagnostic accuracies of the histogram parameters after the receiver operating characteristic curve analysis. Using the parameter offering the highest diagnostic accuracy, a validation process was performed with an independent test set of nine patients.
  
  
  RESULTS
  The 99th percentile of the cumulative nCBV histogram (nCBV C99), mean and peak height differed significantly between low- and high-grade gliomas (P = <0.001, 0.014 and <0.001, respectively) and between grade III and IV gliomas (P = <0.001, 0.001 and <0.001, respectively). The diagnostic accuracy of nCBV C99 was significantly higher than that of the mean nCBV (P = 0.016) in distinguishing high- from low-grade gliomas and was comparable to that of the peak height (P = 1.000). Validation using the two cutoff values of nCBV C99 achieved a diagnostic accuracy of 66.7% (6/9) for the separation of all three glioma grades.
  
  
  CONCLUSIONS
  Cumulative histogram analysis of nCBV using 3 T MRI can be a useful method for preoperative glioma grading. The nCBV C99 value is helpful in distinguishing high- from low-grade gliomas and grade IV from III gliomas.
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Hyungjin
authors.initials: H
authors.lastname: Kim
authors.forename: Seung Hong
authors.initials: SH
authors.lastname: Choi
authors.forename: Ji-Hoon
authors.initials: JH
authors.lastname: Kim
authors.forename: Inseon
authors.initials: I
authors.lastname: Ryoo
authors.forename: Soo Chin
authors.initials: SC
authors.lastname: Kim
authors.forename: Jeong A
authors.initials: JA
authors.lastname: Yeom
authors.forename: Hwaseon
authors.initials: H
authors.lastname: Shin
authors.forename: Seung Chai
authors.initials: SC
authors.lastname: Jung
authors.forename: A Leum
authors.initials: AL
authors.lastname: Lee
authors.forename: Tae Jin
authors.initials: TJ
authors.lastname: Yun
authors.forename: Chul-Kee
authors.initials: CK
authors.lastname: Park
authors.forename: Chul-Ho
authors.initials: CH
authors.lastname: Sohn
authors.forename: Sung-Hye
authors.initials: SH
authors.lastname: Park
mesh_terms: D000328:Adult; D019540:Area Under Curve; D001254:Astrocytoma / Q000473:pathology / Q000503:physiopathology; D001810:Blood Volume / Q000502:physiology*; D001932:Brain Neoplasms / Q000473:pathology* / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D005910:Glioma / Q000473:pathology* / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D012372:ROC Curve