title: Non-invasive grading of brain tumours using dynamic amino acid PET imaging: does it work for 11C-methionine?
abstract: BACKGROUND
  Static imaging of amino acids does not allow differentiation of low versus high grade brain tumours. It has been shown that dynamic imaging of the amino acid analogue (18)F-fluoroethyltyrosine (FET) can achieve this goal. In many centres, (11)C-methionine (MET) is used for tumour imaging, but no clinical studies on the use of dynamic scanning for grading have been performed.
  
  
  METHODS
  Thirty-four patients with primary brain glioma and histopathological confirmation were retrospectively studied using 40 min dynamic MET-PET with 220 MBq 11C-methionine. In relation to histopathological grading, various metabolic indices and temporal parameters as documented by Poepperl et al. (JNM 2006;47:393-403) were analyzed.
  
  
  RESULTS
  None of the evaluated static or temporal parameters allowed discrimination between high and low grade tumours. On average, low grade tumours showed washout after the initial uptake maximum, while both increases and decreases were seen for high grade tumours. Only the relative early versus late uptake ratio showed a trend towards significance (-0.16 +/- 0.17 for low grade versus 0.01 +/- 0.25 for high grade; p = 0.07).
  
  
  CONCLUSIONS
  Unlike FET-PET, the uptake characteristics of MET-PET do not allow classification of low and high grade tumours on an individual patient basis. Since literature data indicate that both tracers have a similar performance regarding biopsy location, tumour delineation, and detection of recurrence, FET-PET should be advocated over MET-PET as its uptake mechanism also allows noninvasive grading in glioma.
authors.affiliation: Division of Nuclear Medicine, University Hospital Leuven and K.U. Leuven, Herestraat 49, Leuven, Belgium.
authors.forename: Gérard
authors.initials: G
authors.lastname: Moulin-Romsée
authors.forename: Eduard
authors.initials: E
authors.lastname: D'Hondt
authors.forename: Tjibbe
authors.initials: T
authors.lastname: de Groot
authors.forename: Jan
authors.initials: J
authors.lastname: Goffin
authors.forename: Raf
authors.initials: R
authors.lastname: Sciot
authors.forename: Luc
authors.initials: L
authors.lastname: Mortelmans
authors.forename: Johan
authors.initials: J
authors.lastname: Menten
authors.forename: Guy
authors.initials: G
authors.lastname: Bormans
authors.forename: Koen
authors.initials: K
authors.lastname: Van Laere
mesh_terms: D000293:Adolescent; D000328:Adult; D001932:Brain Neoplasms / Q000145:classification / Q000000981:diagnostic imaging* / Q000473:pathology*; D002648:Child; D005260:Female; D005910:Glioma / Q000145:classification / Q000000981:diagnostic imaging* / Q000473:pathology*; D006801:Humans; D008297:Male; D008715:Methionine; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D019275:Radiopharmaceuticals; C086242:carbon-11 methionine; D008715:Methionine