title: O-(2-[18F]fluorethyl)-L-tyrosine PET in the clinical evaluation of primary brain tumours.
abstract: OBJECTIVE
  The aim of this study was to evaluate the differential uptake of O-(2-[18F]fluorethyl)-L-tyrosine (FET) in suspected primary brain tumours.
  
  
  METHODS
  Positron emission tomography (PET) was performed in 44 patients referred for the evaluation of a suspected brain tumour. Acquisition consisted of four 10-min frames starting upon i.v. injection of FET. Tumour uptake was calculated as the ratio of maximal tumour intensity to mean activity within a reference region (FETmax).
  
  
  RESULTS
  FET uptake above the cortical level was observed in 35/44 lesions. All histologically confirmed gliomas and many other lesions showed FET uptake to a variable extent. No uptake was observed in nine lesions (one inflammatory lesion, one dysembryoplastic neuroepithelial tumour, one mature teratoma, six lesions without histological confirmation). An analysis of uptake dynamics was done in the patients with increased FET uptake (22 gliomas, three lymphomas, three non-neoplastic lesions, three lesions with unknown histology and four other primaries). Upon classification of tumours into low (i.e. WHO I and II) and high grade (i.e. WHO III and IV), a significant difference in FETmax between the two categories was observed only in the first image frame (0-10 min p.i.), with FETmax=2.0 in low-grade and 3.2 in high-grade tumours (p<0.05); no significant differences were found in frame 4 (30-40 min p.i.), with FETmax=2.4 vs 2.7. Similar results were obtained when the analysis was applied only to astrocytic tumours (2.0 vs 3.1 in the first frame; 2.4 vs 2.6 in the fourth frame).
  
  
  CONCLUSIONS
  These initial results indicate that FET PET is a useful method to identify malignant brain lesions. It appears that high- and low-grade brain tumours exhibit a different uptake kinetics of FET. A kinetic analysis of FET PET may provide additional information in the differentiation of suspected brain lesions.
authors.affiliation: Department of Nuclear Medicine, Münster University, Albert-Schweitzer-Strasse 33, 48149, Münster, Germany. m.weckesser@uni-muenster.de
authors.forename: M
authors.initials: M
authors.lastname: Weckesser
authors.forename: K J
authors.initials: KJ
authors.lastname: Langen
authors.forename: C H
authors.initials: CH
authors.lastname: Rickert
authors.forename: S
authors.initials: S
authors.lastname: Kloska
authors.forename: R
authors.initials: R
authors.lastname: Straeter
authors.forename: K
authors.initials: K
authors.lastname: Hamacher
authors.forename: G
authors.initials: G
authors.lastname: Kurlemann
authors.forename: H
authors.initials: H
authors.lastname: Wassmann
authors.forename: H H
authors.initials: HH
authors.lastname: Coenen
authors.forename: O
authors.initials: O
authors.lastname: Schober
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005462:Fluorine Radioisotopes / Q000493:pharmacokinetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics*
chemical_list: D005462:Fluorine Radioisotopes; C117289:O-(2-fluoroethyl)tyrosine; D019275:Radiopharmaceuticals; D014443:Tyrosine