title: Diffuse intrinsic pontine glioma: is MRI surveillance improved by region of interest volumetry?
abstract: BACKGROUND
  Paediatric diffuse intrinsic pontine glioma (DIPG) is noteworthy for its fibrillary infiltration through neuroparenchyma and its resultant irregular shape. Conventional volumetry methods aim to approximate such irregular tumours to a regular ellipse, which could be less accurate when assessing treatment response on surveillance MRI. Region-of-interest (ROI) volumetry methods, using manually traced tumour profiles on contiguous imaging slices and subsequent computer-aided calculations, may prove more reliable.
  
  
  OBJECTIVE
  To evaluate whether the reliability of MRI surveillance of DIPGs can be improved by the use of ROI-based volumetry.
  
  
  METHODS
  We investigated the use of ROI- and ellipsoid-based methods of volumetry for paediatric DIPGs in a retrospective review of 22 MRI examinations. We assessed the inter- and intraobserver variability of the two methods when performed by four observers.
  
  
  RESULTS
  ROI- and ellipsoid-based methods strongly correlated for all four observers. The ROI-based volumes showed slightly better agreement both between and within observers than the ellipsoid-based volumes (inter-[intra-]observer agreement 89.8% [92.3%] and 83.1% [88.2%], respectively). Bland-Altman plots show tighter limits of agreement for the ROI-based method.
  
  
  CONCLUSIONS
  Both methods are reproducible and transferrable among observers. ROI-based volumetry appears to perform better with greater intra- and interobserver agreement for complex-shaped DIPG.
authors.affiliation: Department of General Radiology, North Tees & Hartlepool NHS Foundation Trust, University Hospital of North Tees, Hardwick Road, Stockton-on-Tees, Cleveland, TS19 8PE, UK, garanriley@hotmail.com.
authors.forename: Garan T
authors.initials: GT
authors.lastname: Riley
authors.forename: Paul A
authors.initials: PA
authors.lastname: Armitage
authors.forename: Ruth
authors.initials: R
authors.lastname: Batty
authors.forename: Paul D
authors.initials: PD
authors.lastname: Griffiths
authors.forename: Vicki
authors.initials: V
authors.lastname: Lee
authors.forename: John
authors.initials: J
authors.lastname: McMullan
authors.forename: Daniel J A
authors.initials: DJ
authors.lastname: Connolly
mesh_terms: D000293:Adolescent; D020295:Brain Stem Neoplasms / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D003287:Contrast Media; D005260:Female; D005910:Glioma / Q000473:pathology*; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D012189:Retrospective Studies
chemical_list: D003287:Contrast Media