title: Role of [(11)C] methionine positron emission tomography in the diagnosis and prediction of survival in brain tumours.
abstract: OBJECTIVE
  [(11)C] methionine (MET) positron-emission tomography (PET) is a useful diagnostic and therapeutic tool in neuro-oncology. The aim of this study was to evaluate the relationship between MET uptake and the histopathological grade in both primary brain tumours and brain metastases. A secondary goal was to assess the relationship between MET uptake and patients' survival after surgery.
  
  
  METHODS
  We reviewed a consecutive series of 43 PET studies performed at our institution. Out of the 43 patients studied, 35 harboured primary brain tumours (3 grade I, 12 grade II, 7 grade III and 13 grade IV) and 8 patients had brain metastases. We measured the tumour/cortex ratio (T/C ratio) on each PET study and we investigated the correlations among the tracer uptake, tumour grade, tumour type, MRI parameters and outcome.
  
  
  RESULTS
  The mean T/C ratio was 1.8 ± 0.9 for benign lesions and low grade gliomas (grade I and II) and 2.7 ± 1 for high grade gliomas (grade III and IV). In brain metastases it was 2.5 ± 0.7, with a significant difference in MET uptake between low and high grades gliomas (P=0.03). There was no statistically significant difference among all different histologic types. We found that both contrast enhancement and perfusion studies correlate with MET uptake in brain tumours. Moreover, in Kaplan-Meier curves, the T/C ratio adversely affects long term survival in patients with brain tumours (P=0.01).
  
  
  CONCLUSIONS
  MET PET appears to be useful in diagnosis and evaluation of potential malignancy in brain tumours. MET uptake is also related with the overall survival in patients with brain tumours. Nevertheless, further studies are needed in order to define its possible clinical implications in identifying patients at high risk of tumour progression or resistance to therapy.
authors.affiliation: Department of Neurosurgery, Universitat Autònoma de Barcelona, Hospital Vall d'Hebron, Barcelona, Spain. Electronic address: marta.cicuendez@gmail.com.
authors.forename: Marta
authors.initials: M
authors.lastname: Cicuendez
authors.affiliation: Department of Nuclear Medicine, Universitat Autònoma de Barcelona, Hospital Vall d'Hebron, Barcelona, Spain.
authors.forename: Carles
authors.initials: C
authors.lastname: Lorenzo-Bosquet
authors.affiliation: Department of Nuclear Medicine, Universitat Autònoma de Barcelona, Hospital Vall d'Hebron, Barcelona, Spain.
authors.forename: Gemma
authors.initials: G
authors.lastname: Cuberas-Borrós
authors.affiliation: Department of Neurosurgery, Universitat Autònoma de Barcelona, Hospital Vall d'Hebron, Barcelona, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Martinez-Ricarte
authors.affiliation: Department of Neurosurgery, Universitat Autònoma de Barcelona, Hospital Vall d'Hebron, Barcelona, Spain.
authors.forename: Esteban
authors.initials: E
authors.lastname: Cordero
authors.affiliation: Department of Neuropathology, Universitat Autònoma de Barcelona, Hospital Vall d'Hebron, Barcelona, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Martinez-Saez
authors.affiliation: Department of Nuclear Medicine, Universitat Autònoma de Barcelona, Hospital Vall d'Hebron, Barcelona, Spain.
authors.forename: Joan
authors.initials: J
authors.lastname: Castell-Conesa
authors.affiliation: Department of Neurosurgery, Universitat Autònoma de Barcelona, Hospital Vall d'Hebron, Barcelona, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Sahuquillo
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001254:Astrocytoma / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000401:mortality; D001932:Brain Neoplasms / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000401:mortality / Q000556:secondary; D002250:Carbon Radioisotopes; D004806:Ependymoma / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000401:mortality; D005260:Female; D018303:Ganglioglioma / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000401:mortality; D005909:Glioblastoma / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000401:mortality; D005910:Glioma / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000401:mortality; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008715:Methionine; D008875:Middle Aged; D009837:Oligodendroglioma / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000401:mortality; D049268:Positron-Emission Tomography; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate; D055815:Young Adult
chemical_list: D002250:Carbon Radioisotopes; D008715:Methionine
keywords: Brain metastases; Brain tumours; Gliomas; MET-PET; Methionine; Positron-emission tomography