title: Comparison of the amino acid tracers 18F-FET and 18F-DOPA in high-grade glioma patients.
abstract: High-grade gliomas (HGGs) are the most common malignant primary tumors of the central nervous system. PET probes of amino acid transport such as O-(2-(18)F-fluoroethyl)-l-tyrosine ((18)F-FET), 3,4-dihydroxy-6-(18)F-fluoro-l-phenylalanine ((18)F-DOPA), and (11)C-methionine ((11)C-MET) detect primary and recurrent tumors with a high accuracy. (18)F-FET is predominantly used in Europe, whereas amino acid transport imaging is infrequently done in the United States. The aim of this study was to determine whether (18)F-FET and (18)F-DOPA PET/CT provide comparable information in HGG.
  
  
  METHODS
  Thirty (18)F-FET and (18)F-DOPA PET/CT scans were obtained before surgery or biopsy in 27 patients with high clinical suspicion for primary or recurrent HGG (5 primary, 22 recurrent tumors). (18)F-FET and (18)F-DOPA PET/CT images were compared visually and semiquantitatively (maximum standardized uptake value [SUV(max)], mean SUV [SUV(mean)]). Background (SUV(max) and SUV(mean)) and tumor-to-background ratios (TBRs) were calculated for both PET probes. The degree of (18)F-DOPA uptake in the basal ganglia (SUV(mean)) was also assessed.
  
  
  RESULTS
  Visual analysis revealed no difference in tumor uptake pattern between the 2 PET probes. The SUV(mean) and SUV(max) for (18)F-FET were higher than those of (18)F-DOPA (4.0 ± 2.0 and 4.9 ± 2.3 vs. 3.5 ± 1.6 and 4.3 ± 2.0, respectively; all P < 0.001). TBRs for SUV(mean) but not for SUV(max) were significantly higher for (18)F-FET than (18)F-DOPA (TBR SUV(mean): 3.8 ± 1.7 vs. 3.4 ± 1.2, P = 0.004; TBR SUV(max): 3.3 ± 1.6 and 3.0 ± 1.1, respectively; P = 0.086). (18)F-DOPA uptake by the basal ganglia was present (SUV(mean), 2.6 ± 0.7) but did not affect tumor visualization.
  
  
  CONCLUSIONS
  Whereas visual analysis revealed no significant differences in uptake pattern for (18)F-FET and (18)F-DOPA in patients with primary or recurrent HGG, both SUVs and TBRs for SUV(mean) were significantly higher for (18)F-FET. However, regarding tumor delineation, both tracers performed equally well and seem equally feasible for imaging of primary and recurrent HGG. These findings suggest that both PET probes can be used based on availability in multicenter trials.
authors.affiliation: Department of Nuclear Medicine, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Constantin
authors.initials: C
authors.lastname: Lapa
authors.affiliation: Department of Neurosurgery, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Linsenmann
authors.affiliation: Department of Neuropathology, Institute of Pathology, University of Würzburg, Würzburg, Germany.
authors.forename: Camelia Maria
authors.initials: CM
authors.lastname: Monoranu
authors.affiliation: Department of Nuclear Medicine, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Samuel
authors.initials: S
authors.lastname: Samnick
authors.affiliation: Department of Nuclear Medicine, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Andreas K
authors.initials: AK
authors.lastname: Buck
authors.affiliation: Department of Nuclear Medicine, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Bluemel
authors.affiliation: Ahmanson Translational Imaging Division, Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California; and.
authors.forename: Johannes
authors.initials: J
authors.lastname: Czernin
authors.affiliation: Department of Neurosurgery, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Almuth F
authors.initials: AF
authors.lastname: Kessler
authors.affiliation: Department of Neuroradiology, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Gyoergy A
authors.initials: GA
authors.lastname: Homola
authors.affiliation: Department of Neurosurgery, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Ralf-Ingo
authors.initials: RI
authors.lastname: Ernestus
authors.affiliation: Department of Neurosurgery, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Mario
authors.initials: M
authors.lastname: Löhr
authors.affiliation: Department of Nuclear Medicine, University Hospital Würzburg, Würzburg, Germany Ahmanson Translational Imaging Division, Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California; and herrmann_k1@ukw.de.
authors.forename: Ken
authors.initials: K
authors.lastname: Herrmann
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000596:Amino Acids / Q000493:pharmacokinetics*; D001479:Basal Ganglia / Q000000981:diagnostic imaging; D001706:Biopsy; D001921:Brain / Q000000981:diagnostic imaging; D001932:Brain Neoplasms / Q000000981:diagnostic imaging*; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D005260:Female; D005910:Glioma / Q000000981:diagnostic imaging*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011877:Radionuclide Imaging; D012008:Recurrence; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics
chemical_list: D000596:Amino Acids; C545932:(18F)fluoroethyltyrosine; C043437:fluorodopa F 18; D014443:Tyrosine; D004295:Dihydroxyphenylalanine
keywords: F-DOPA; FET; PET; amino acids; glioblastoma; positron emission tomography