title: Utility of positron emission tomography for tumour surveillance in children with neurofibromatosis type 1.
abstract: OBJECTIVE
  There is little consensus regarding optimal surveillance of optic pathway glioma (OPG) and plexiform neurofibroma (PNF) in childhood neurofibromatosis type 1 (NF1). (18)F-2-Fluoro-2-deoxy-D: -glucose (FDG) positron emission tomography and computed tomography (PET/CT) is employed in the surveillance of adult PNFs; but its utility has neither been specifically studied in children with PNFs nor in children with OPG.
  
  
  METHODS
  Review of PET/CT studies was performed in NF1 children with OPG or PNF. FDG-avidity of tumours was semi-quantitatively analysed and graded by calculating the maximum standardised uptake value (SUV(max)) [grade 1: <3 (low), grade 2: >3-<4 (intermediate), grade 3: >4 (intense)].
  
  
  RESULTS
  Eighteen children (ten girls; median age: 8.5-years) had PET/CT. Nineteen OPGs were imaged. The SUV(max) could be measured in 16. Ten were grade 1 and three each were grade 2 and grade 3. FDG-avidity reduced from grade 3 to grade 1 in two symptomatic OPGs following chemotherapy and this was associated with clinical improvement. PET/CT diagnosed symptomatic OPGs with a sensitivity of 0.625 [95% confidence interval (CI): 0.259-0.897] and specificity of 0.875 (95% CI: 0.466-0.993). Sixteen PNFs were imaged. Twelve were grade 1 and two each were grade 2 and grade 3. The two grade 3 PNFs were confirmed malignant peripheral nerve sheath tumours. PET/CT diagnosed malignant transformation with a sensitivity of 1.0 (95% CI: 0.197-1.0) and specificity of 0.857 (95% CI: 0.561-0.974).
  
  
  CONCLUSIONS
  PET/CT may contribute useful information to the surveillance of OPG in childhood NF1-particularly to identify progressive, symptomatic tumours. As in adults, PET/CT is useful for the detection of malignant transformation in PNFs in children with NF1.
authors.affiliation: Division of Neurology, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, M5G 1X8, Canada. mahendranath.moharir@sickkids.ca
authors.forename: Mahendranath
authors.initials: M
authors.lastname: Moharir
authors.forename: Kevin
authors.initials: K
authors.lastname: London
authors.forename: Robert
authors.initials: R
authors.lastname: Howman-Giles
authors.forename: Kathryn
authors.initials: K
authors.lastname: North
mesh_terms: D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D018318:Neurofibroma, Plexiform / Q000000981:diagnostic imaging; D009456:Neurofibromatosis 1 / Q000000981:diagnostic imaging*; D020339:Optic Nerve Glioma / Q000000981:diagnostic imaging; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D019788:Fluorodeoxyglucose F18