title: Multiparametric differentiation of posterior fossa tumors in children using diffusion-weighted imaging and short echo-time 1H-MR spectroscopy.
abstract: OBJECTIVE
  To assess the combined value of diffusion-weighted imaging (DWI) and proton magnetic resonance spectroscopy (1H-MRS) in differentiating medulloblastoma, ependymoma, pilocytic astrocytoma, and infiltrating glioma in a pediatric population.
  
  
  METHODS
  A total of 17 children with untreated posterior fossa tumors (seven medulloblastoma, four infiltrating glioma, two ependymoma, and four pilocytic astrocytoma), were investigated with conventional MRI, DWI, and MRS using a single-voxel technique. Within the nonnecrotic tumor core, apparent diffusion coefficient (ADC) values using a standardized region of interest (ROI) were retrieved. Quantification of water signal and analysis of metabolite signals from MRS measurements in the same tumorous area were reviewed using multivariant linear discriminant analysis.
  
  
  RESULTS
  Combination of ADC values and metabolites, which were normalized using water as an internal standard, allowed discrimination between the four tumor groups with a likelihood below 1 x 10(-9). Positive predictive value was 1 in all cases. Tumors could not be discriminated when using metabolite ratios or ADC values alone, nor could they be differentiated using creatine (Cr) as an internal reference even in combination with ADC values.
  
  
  CONCLUSIONS
  Linear discriminant analysis using DWI and MRS using water as internal reference, fully discriminates the four most frequent posterior fossa tumors in children.
authors.affiliation: Department of Pediatric Radiology, University Children's Hospital Universitäts Kinderspital beider Basel, Basel, Switzerland. jacques.schneider@ukbb.ch
authors.forename: J F
authors.initials: JF
authors.lastname: Schneider
authors.forename: S
authors.initials: S
authors.lastname: Confort-Gouny
authors.forename: A
authors.initials: A
authors.lastname: Viola
authors.forename: Y
authors.initials: Y
authors.lastname: Le Fur
authors.forename: P
authors.initials: P
authors.lastname: Viout
authors.forename: M
authors.initials: M
authors.lastname: Bennathan
authors.forename: F
authors.initials: F
authors.lastname: Chapon
authors.forename: D
authors.initials: D
authors.lastname: Figarella-Branger
authors.forename: P
authors.initials: P
authors.lastname: Cozzone
authors.forename: N
authors.initials: N
authors.lastname: Girard
mesh_terms: D000293:Adolescent; D001254:Astrocytoma / Q000473:pathology; D001932:Brain Neoplasms / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D003388:Cranial Fossa, Posterior / Q000473:pathology*; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging; D016002:Discriminant Analysis; D004806:Ependymoma / Q000473:pathology; D005260:Female; D005910:Glioma / Q000473:pathology; D006801:Humans; D007223:Infant; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008527:Medulloblastoma / Q000473:pathology; D012189:Retrospective Studies; D018709:Statistics, Nonparametric