title: Utility of apparent diffusion coefficient ratios in distinguishing common pediatric cerebellar tumors.
abstract: OBJECTIVE
  The aim of this study was to identify clinically useful tumor/normal brain apparent diffusion coefficient (ADC) ratios for distinguishing common pediatric cerebellar tumors.
  
  
  METHODS
  Review of medical records revealed 79 patients with cerebellar tumors who underwent preoperative magnetic resonance imaging, including diffusion-weighted imaging sequences, and surgery. There were 31 pilocytic astrocytomas, 27 medulloblastomas, 14 ependymomas, and seven atypical teratoid/rhabdoid tumors. ADC values were measured by placing regions of interest on the solid tumor and normal brain parenchyma by two reviewers. Tumor/normal brain ADC ratios were calculated.
  
  
  RESULTS
  Mean ADC values of the pilocytic astrocytomas were greater than those of ependymomas, whose mean ADC values were greater than those of medulloblastomas and atypical teratoid/rhabdoid tumors. Using a tumor/normal brain ADC ratio threshold of 1.70 to distinguish pilocytic astrocytomas from ependymomas, sensitivity of 92% and specificity of 79% were achieved. A tumor/normal brain ADC ratio threshold of 1.20 enabled the sorting of ependymomas from medulloblastomas with sensitivity of 93% and specificity of 88%.
  
  
  CONCLUSIONS
  Tumor/normal brain ADC ratios allow the distinguishing of common pediatric cerebellar tumors.
authors.affiliation: Department of Radiology, Dartmouth Medical School, Hanover, New Hampshire, USA.
authors.forename: Barjor
authors.initials: B
authors.lastname: Gimi
authors.forename: Kevin
authors.initials: K
authors.lastname: Cederberg
authors.forename: Betul
authors.initials: B
authors.lastname: Derinkuyu
authors.forename: Lynn
authors.initials: L
authors.lastname: Gargan
authors.forename: Kadriye M
authors.initials: KM
authors.lastname: Koral
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Bowers
authors.forename: Korgun
authors.initials: K
authors.lastname: Koral
mesh_terms: D000293:Adolescent; D001254:Astrocytoma / Q000175:diagnosis*; D002528:Cerebellar Neoplasms / Q000175:diagnosis* / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging; D004806:Ependymoma / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D008527:Medulloblastoma / Q000175:diagnosis*; D018335:Rhabdoid Tumor / Q000175:diagnosis*; D012680:Sensitivity and Specificity; D013724:Teratoma / Q000175:diagnosis