title: Although Non-diagnostic Between Necrosis and Recurrence, FDG PET/CT Assists Management of Brain Tumours After Radiosurgery.
abstract: OBJECTIVE
  To re-evaluate the role of (18)F-fluoro-deoxy-D-glucose (FDG) positron emission tomography/ computer assisted tomography (PET/CT) co-registered with magnetic resonance imaging (MRI) in differentiating adverse radiation effect (ARE) from tumour recurrence after Gamma Knife radiosurgery of brain tumours.
  
  
  METHODS
  Twenty-seven PET/CT studies co-registered with MRI were performed on 16 patients after radiosurgery, with 12/16 patients having multiple radiosurgery treatments. Long term follow-up was used for evaluation, with 3/16 patients being histopathologically confirmed.
  
  
  RESULTS
  PET/CT was positive in all studies in 6/16 patients, negative in all studies in 6/16 and changed from negative to positive in one. In 2/16 patients, PET/CT was both positive and negative in separate tumour foci. In 9/16 cases with a positive PET/CT, tumour was confirmed. In 6/16 patients with a negative PET/CT, 3/6 had recurrence and 3/6 ARE. In 1/16, equivocal results became negative after retreatment. PET/CT/MRI identified tumour within ARE. Sensitivity of PET/CT/MRI proved to be 64.7%, and specificity 100%.
  
  
  CONCLUSIONS
  PET/CT/MRI assists management, by revealing metabolism rather than histology.
authors.affiliation: Department of Radiosurgery and Neurosurgery, Diagnostic and Therapeutic Centre 'Hygeia', Athens, Greece.
authors.forename: Michael
authors.initials: M
authors.lastname: Torrens
authors.affiliation: Department of Medical Physics, Medical School, National and Kapodistrian University of Athens, Athens, Greece j.malamitsi@yahoo.gr.
authors.forename: Julia
authors.initials: J
authors.lastname: Malamitsi
authors.affiliation: Department of Medical Physics, Medical School, National and Kapodistrian University of Athens, Athens, Greece Department of Medical Physics, Diagnostic and Therapeutic Centre 'Hygeia', Athens, Greece.
authors.forename: Pantelis
authors.initials: P
authors.lastname: Karaiskos
authors.affiliation: Department of Nuclear Medicine, Diagnostic and Therapeutic Centre 'Hygeia', Athens, Greece.
authors.forename: Varvara
authors.initials: V
authors.lastname: Valotassiou
authors.affiliation: Department of CT and MRI, Diagnostic and Therapeutic Centre 'Hygeia', Athens, Greece.
authors.forename: Fotis
authors.initials: F
authors.lastname: Laspas
authors.affiliation: Department of CT and MRI, Diagnostic and Therapeutic Centre 'Hygeia', Athens, Greece.
authors.forename: John
authors.initials: J
authors.lastname: Andreou
authors.affiliation: Department of Radiosurgery and Neurosurgery, Diagnostic and Therapeutic Centre 'Hygeia', Athens, Greece.
authors.forename: Christos
authors.initials: C
authors.lastname: Stergiou
authors.affiliation: Department of Nuclear Medicine, Diagnostic and Therapeutic Centre 'Hygeia', Athens, Greece.
authors.forename: Vassilis
authors.initials: V
authors.lastname: Prassopoulos
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary* / Q000601:surgery; D019468:Disease Management; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D009369:Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods*; D011379:Prognosis; D019275:Radiopharmaceuticals; D016634:Radiosurgery
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: Gamma Knife; MRI; PET/CT; adverse radiation effect; brain metastases; glioma; necrosis; radiosurgery