title: Metrics and textural features of MRI diffusion to improve classification of pediatric posterior fossa tumors.
abstract: OBJECTIVE
  Qualitative radiologic MR imaging review affords limited differentiation among types of pediatric posterior fossa brain tumors and cannot detect histologic or molecular subtypes, which could help to stratify treatment. This study aimed to improve current posterior fossa discrimination of histologic tumor type by using support vector machine classifiers on quantitative MR imaging features.
  
  
  METHODS
  This retrospective study included preoperative MRI in 40 children with posterior fossa tumors (17 medulloblastomas, 16 pilocytic astrocytomas, and 7 ependymomas). Shape, histogram, and textural features were computed from contrast-enhanced T2WI and T1WI and diffusivity (ADC) maps. Combinations of features were used to train tumor-type-specific classifiers for medulloblastoma, pilocytic astrocytoma, and ependymoma types in separation and as a joint posterior fossa classifier. A tumor-subtype classifier was also produced for classic medulloblastoma. The performance of different classifiers was assessed and compared by using randomly selected subsets of training and test data.
  
  
  RESULTS
  ADC histogram features (25th and 75th percentiles and skewness) yielded the best classification of tumor type (on average >95.8% of medulloblastomas, >96.9% of pilocytic astrocytomas, and >94.3% of ependymomas by using 8 training samples). The resulting joint posterior fossa classifier correctly assigned >91.4% of the posterior fossa tumors. For subtype classification, 89.4% of classic medulloblastomas were correctly classified on the basis of ADC texture features extracted from the Gray-Level Co-Occurence Matrix.
  
  
  CONCLUSIONS
  Support vector machine-based classifiers using ADC histogram features yielded very good discrimination among pediatric posterior fossa tumor types, and ADC textural features show promise for further subtype discrimination. These findings suggest an added diagnostic value of quantitative feature analysis of diffusion MR imaging in pediatric neuro-oncology.
authors.affiliation: From the Division of Radiological and Imaging Sciences (D.R.G., A.A., M.M., R.A.D., R.G.G., D.P.A.)Children's Brain Tumor Research Centre (D.R.G., L.M., R.G.G., D.P.A.), University of Nottingham, Nottingham, UK.
authors.forename: D
authors.initials: D
authors.lastname: Rodriguez Gutierrez
authors.affiliation: From the Division of Radiological and Imaging Sciences (D.R.G., A.A., M.M., R.A.D., R.G.G., D.P.A.)Nottingham University Hospital Trust (A.A., L.M., T.J., R.A.D.), Nottingham, UK.
authors.forename: A
authors.initials: A
authors.lastname: Awwad
authors.affiliation: Children's Brain Tumor Research Centre (D.R.G., L.M., R.G.G., D.P.A.), University of Nottingham, Nottingham, UKNottingham University Hospital Trust (A.A., L.M., T.J., R.A.D.), Nottingham, UK.
authors.forename: L
authors.initials: L
authors.lastname: Meijer
authors.affiliation: From the Division of Radiological and Imaging Sciences (D.R.G., A.A., M.M., R.A.D., R.G.G., D.P.A.).
authors.forename: M
authors.initials: M
authors.lastname: Manita
authors.affiliation: Nottingham University Hospital Trust (A.A., L.M., T.J., R.A.D.), Nottingham, UK.
authors.forename: T
authors.initials: T
authors.lastname: Jaspan
authors.affiliation: From the Division of Radiological and Imaging Sciences (D.R.G., A.A., M.M., R.A.D., R.G.G., D.P.A.)Nottingham University Hospital Trust (A.A., L.M., T.J., R.A.D.), Nottingham, UK.
authors.forename: R A
authors.initials: RA
authors.lastname: Dineen
authors.affiliation: From the Division of Radiological and Imaging Sciences (D.R.G., A.A., M.M., R.A.D., R.G.G., D.P.A.)Children's Brain Tumor Research Centre (D.R.G., L.M., R.G.G., D.P.A.), University of Nottingham, Nottingham, UK.
authors.forename: R G
authors.initials: RG
authors.lastname: Grundy
authors.affiliation: From the Division of Radiological and Imaging Sciences (D.R.G., A.A., M.M., R.A.D., R.G.G., D.P.A.) dorothee.auer@nottingham.ac.uk.
authors.forename: D P
authors.initials: DP
authors.lastname: Auer
mesh_terms: D000293:Adolescent; D000465:Algorithms; D001185:Artificial Intelligence; D001254:Astrocytoma / Q000145:classification / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D004806:Ependymoma / Q000145:classification / Q000473:pathology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007223:Infant; D015192:Infratentorial Neoplasms / Q000145:classification / Q000473:pathology*; D008297:Male; D008527:Medulloblastoma / Q000145:classification / Q000473:pathology*; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity