title: Comparison of (18)F-FET and (18)F-FDG PET in brain tumors.
abstract: The purpose of this study was to compare the diagnostic value of positron emission tomography (PET) using [(18)F]-fluorodeoxyglucose ((18)F-FDG) and O-(2-[(18)F]fluoroethyl)-l-tyrosine ((18)F-FET) in patients with brain lesions suspicious of cerebral gliomas.
  
  
  METHODS
  Fifty-two patients with suspicion of cerebral glioma were included in this study. From 30 to 50 min after injection of 180 MBq (18)F-FET, a first PET scan ((18)F-FET scan) was performed. Thereafter, 240 MBq (18)F-FDG was injected and a second PET scan was acquired from 30 to 60 min after the second injection ((18)F-FET/(18)F-FDG scan). The cerebral accumulation of (18)F-FDG was calculated by decay corrected subtraction of the (18)F-FET scan from the (18)F-FET/(18)F-FDG scan. Tracer uptake was evaluated by visual scoring and by lesion-to-background (L/B) ratios. The imaging results were compared with the histological results and prognosis.
  
  
  RESULTS
  Histology revealed 24 low-grade gliomas (LGG) of World Health Organization (WHO) Grade II and 19 high-grade gliomas (HGG) of WHO Grade III or IV, as well as nine others, mainly benign histologies. The gliomas showed increased (18)F-FET uptake (>normal brain) in 86% and increased (18)F-FDG uptake (>white matter) in 35%. (18)F-FET PET provided diagnostically useful delineation of tumor extent while this was impractical with (18)F-FDG due to high tracer uptake in the gray matter. A local maximum in the tumor area for biopsy guidance could be identified with (18)F-FET in 76% and with (18)F-FDG in 28%. The L/B ratios showed significant differences between LGG and HGG for both tracers but considerable overlap so that reliable preoperative grading was not possible. A significant correlation of tracer uptake with overall survival was found with (18)F-FDG only. In some benign lesions like abscesses, increased uptake was observed for both tracers indicating a limited specificity of both techniques.
  
  
  CONCLUSIONS
  (18)F-FET PET is superior to (18)F-FDG for biopsy guidance and treatment planning of cerebral gliomas. The uptake of (18)F-FDG is associated with prognosis, but the predictive value is limited and a histological evaluation of tumor tissue remains necessary. Therefore, amino acids like (18)F-FET are the preferred PET tracers for the clinical management of cerebral gliomas.
authors.affiliation: Institute of Neuroscience and Medicine, Forschungszentrum Jülich, D-52425 Jülich, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Pauleit
authors.forename: Gabriele
authors.initials: G
authors.lastname: Stoffels
authors.forename: Ansgar
authors.initials: A
authors.lastname: Bachofner
authors.forename: Frank W
authors.initials: FW
authors.lastname: Floeth
authors.forename: Michael
authors.initials: M
authors.lastname: Sabel
authors.forename: Hans
authors.initials: H
authors.lastname: Herzog
authors.forename: Lutz
authors.initials: L
authors.lastname: Tellmann
authors.forename: Paul
authors.initials: P
authors.lastname: Jansen
authors.forename: Guido
authors.initials: G
authors.lastname: Reifenberger
authors.forename: Kurt
authors.initials: K
authors.lastname: Hamacher
authors.forename: Heinz H
authors.initials: HH
authors.lastname: Coenen
authors.forename: Karl-Josef
authors.initials: KJ
authors.lastname: Langen
mesh_terms: D000293:Adolescent; D000368:Aged; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D011446:Prospective Studies; D014443:Tyrosine / Q000031:analogs & derivatives*; D055815:Young Adult
chemical_list: C117289:O-(2-fluoroethyl)tyrosine; D019788:Fluorodeoxyglucose F18; D014443:Tyrosine