title: Dynamic O-(2-18F-fluoroethyl)-L-tyrosine positron emission tomography differentiates brain metastasis recurrence from radiation injury after radiotherapy.
abstract: The aim of this study was to investigate the potential of dynamic O-(2-[18F]fluoroethyl)-L-tyrosine (18F-FET) PET for differentiating local recurrent brain metastasis from radiation injury after radiotherapy since contrast-enhanced MRI often remains inconclusive.
  
  
  
  Sixty-two patients (mean age, 55 ± 11 y) with single or multiple contrast-enhancing brain lesions (n = 76) on MRI after radiotherapy of brain metastases (predominantly stereotactic radiosurgery) were investigated with dynamic 18F-FET PET. Maximum and mean tumor-to-brain ratios (TBRmax, TBRmean) of 18F-FET uptake were determined (20-40 min postinjection) as well as tracer uptake kinetics (ie, time-to-peak and slope of time-activity curves). Diagnoses were confirmed histologically (34%; 26 lesions in 25 patients) or by clinical follow-up (66%; 50 lesions in 37 patients). Diagnostic accuracies of PET parameters for the correct identification of recurrent brain metastasis were evaluated by receiver-operating-characteristic analyses or the chi-square test.
  
  
  
  TBRs were significantly higher in recurrent metastases (n = 36) than in radiation injuries (n = 40) (TBRmax 3.3 ± 1.0 vs 2.2 ± 0.4, P < .001; TBRmean 2.2 ± 0.4 vs 1.7 ± 0.3, P < .001). The highest accuracy (88%) for diagnosing local recurrent metastasis could be obtained with TBRs in combination with the slope of time-activity curves (P < .001).
  
  
  
  The results of this study confirm previous preliminary observations that the combined evaluation of the TBRs of 18F-FET uptake and the slope of time-activity curves can differentiate local brain metastasis recurrence from radiation-induced changes with high accuracy. 18F-FET PET may thus contribute significantly to the management of patients with brain metastases.
authors.affiliation: Department of Neurology, University of Cologne, Cologne, Germany.
authors.forename: Garry
authors.initials: G
authors.lastname: Ceccon
authors.affiliation: Institute of Neuroscience and Medicine, Research Center Jülich, Jülich, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Lohmann
authors.affiliation: Institute of Neuroscience and Medicine, Research Center Jülich, Jülich, Germany.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Stoffels
authors.affiliation: Institute of Neuroscience and Medicine, Research Center Jülich, Jülich, Germany.
authors.forename: Natalie
authors.initials: N
authors.lastname: Judov
authors.affiliation: Institute of Neuroscience and Medicine, Research Center Jülich, Jülich, Germany.|Department of Neurology, University of Aachen, Aachen, Germany.
authors.forename: Christian P
authors.initials: CP
authors.lastname: Filss
authors.affiliation: Department of Neurosurgery, University of Düsseldorf, Düsseldorf, Germany.
authors.forename: Marion
authors.initials: M
authors.lastname: Rapp
authors.affiliation: Department of Neurology, University of Cologne, Cologne, Germany.
authors.forename: Elena
authors.initials: E
authors.lastname: Bauer
authors.affiliation: Department of Neurosurgery, University of Cologne, Cologne, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Hamisch
authors.affiliation: Department of Stereotaxy and Functional Neurosurgery, University of Cologne, Cologne, Germany.
authors.forename: Maximilian I
authors.initials: MI
authors.lastname: Ruge
authors.affiliation: Department of Radiation Oncology, University of Cologne, Cologne, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Kocher
authors.affiliation: Department of Neuropathology, University of Bonn, Bonn, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Kuchelmeister
authors.affiliation: Department of Neuropathology, University of Aachen, Aachen, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Sellhaus
authors.affiliation: Department of Neurosurgery, University of Düsseldorf, Düsseldorf, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Sabel
authors.affiliation: Department of Neurology, University of Cologne, Cologne, Germany.|Institute of Neuroscience and Medicine, Research Center Jülich, Jülich, Germany.
authors.forename: Gereon R
authors.initials: GR
authors.lastname: Fink
authors.affiliation: Institute of Neuroscience and Medicine, Research Center Jülich, Jülich, Germany.|Department of Neurology, University of Aachen, Aachen, Germany.|Jülich-Aachen Research Alliance (JARA) - Section JARA-Brain, Jülich and Aachen, Germany.
authors.forename: Nadim J
authors.initials: NJ
authors.lastname: Shah
authors.affiliation: Institute of Neuroscience and Medicine, Research Center Jülich, Jülich, Germany.|Department of Neuropathology, University of Aachen, Aachen, Germany.|Department of Nuclear Medicine, University of Aachen, Aachen, Germany.
authors.forename: Karl-Josef
authors.initials: KJ
authors.lastname: Langen
authors.affiliation: Department of Neurology, University of Cologne, Cologne, Germany.|Institute of Neuroscience and Medicine, Research Center Jülich, Jülich, Germany.|Center of Integrated Oncology (CIO), University of Cologne, Cologne, Germany.
authors.forename: Norbert
authors.initials: N
authors.lastname: Galldiks
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000556:secondary*; D003937:Diagnosis, Differential; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography / Q000379:methods*; D011379:Prognosis; D011832:Radiation Injuries / Q000000981:diagnostic imaging* / Q000209:etiology / Q000378:metabolism; D019275:Radiopharmaceuticals / Q000378:metabolism; D011878:Radiotherapy / Q000009:adverse effects*; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism; D055815:Young Adult
chemical_list: C117289:O-(2-fluoroethyl)tyrosine; D019275:Radiopharmaceuticals; D014443:Tyrosine
keywords: FET PET; kinetic analysis; radiation-induced changes; radionecrosis; stereotactic radiosurgery