title: Impact of [18F]-fluoro-ethyl-tyrosine PET imaging on target definition for radiation therapy of high-grade glioma.
abstract: BACKGROUND
  We sought to assess the impact of amino-acid (18)F-fluoro-ethyl-tyrosine (FET) positron emission tomography (PET) on the volumetric target definition for radiation therapy of high-grade glioma versus the current standard using MRI alone. Specifically, we investigated the influence of tumor grade, MR-defined tumor volume, and the extent of surgical resection on PET positivity.
  
  
  METHODS
  Fifty-four consecutive high-grade glioma patients (World Health Organization grades III-IV) with confirmed histology were scanned using FET-PET/CT and T1 and T2/fluid attenuated inversion recovery MRI. Gross tumor volume and clinical target volumes (CTVs) were defined in a blinded fashion based on MRI and subsequently PET, and volumetric analysis was performed. The extent of the surgical resection was reviewed using postoperative MRI.
  
  
  RESULTS
  Overall, for ∼ 90% of the patients, the PET-positive volumes were encompassed by T1 MRI with contrast-defined tumor plus a 20-mm margin. The tumor volume defined by PET was larger for glioma grade IV (P < .001) and smaller for patients with more extensive surgical resection (P = .004). The margin required to be added to the MRI-defined tumor in order to fully encompass the FET-PET positive volume tended to be larger for grade IV tumors (P = .018).
  
  
  CONCLUSIONS
  With an unchanged CTV margin and by including FET-PET for gross tumor volume definition, the CTV will increase moderately for most patients, and quite substantially for a minority of patients. Patients with grade IV glioma were found to be the primary candidates for PET-guided radiation therapy planning.
authors.affiliation: Department of Oncology, Section of Radiotherapy, Rigshospitalet, Copenhagen, Denmark (P.M.a.R., J.C., S.A.E., M.J.L., L.O.); Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark (P.M.a.R., M.J.L.); Department of Clinical Physiology, Nuclear Medicine, and PET, Rigshospitalet, Copenhagen, Denmark (I.L., J.C.); Section of Radiation Oncology, Skåne University Hospital, Lund, Sweden (S.E.).
authors.forename: Per
authors.initials: P
authors.lastname: Munck Af Rosenschold
authors.affiliation: Department of Oncology, Section of Radiotherapy, Rigshospitalet, Copenhagen, Denmark (P.M.a.R., J.C., S.A.E., M.J.L., L.O.); Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark (P.M.a.R., M.J.L.); Department of Clinical Physiology, Nuclear Medicine, and PET, Rigshospitalet, Copenhagen, Denmark (I.L., J.C.); Section of Radiation Oncology, Skåne University Hospital, Lund, Sweden (S.E.).
authors.forename: Junia
authors.initials: J
authors.lastname: Costa
authors.affiliation: Department of Oncology, Section of Radiotherapy, Rigshospitalet, Copenhagen, Denmark (P.M.a.R., J.C., S.A.E., M.J.L., L.O.); Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark (P.M.a.R., M.J.L.); Department of Clinical Physiology, Nuclear Medicine, and PET, Rigshospitalet, Copenhagen, Denmark (I.L., J.C.); Section of Radiation Oncology, Skåne University Hospital, Lund, Sweden (S.E.).
authors.forename: Svend Aage
authors.initials: SA
authors.lastname: Engelholm
authors.affiliation: Department of Oncology, Section of Radiotherapy, Rigshospitalet, Copenhagen, Denmark (P.M.a.R., J.C., S.A.E., M.J.L., L.O.); Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark (P.M.a.R., M.J.L.); Department of Clinical Physiology, Nuclear Medicine, and PET, Rigshospitalet, Copenhagen, Denmark (I.L., J.C.); Section of Radiation Oncology, Skåne University Hospital, Lund, Sweden (S.E.).
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Lundemann
authors.affiliation: Department of Oncology, Section of Radiotherapy, Rigshospitalet, Copenhagen, Denmark (P.M.a.R., J.C., S.A.E., M.J.L., L.O.); Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark (P.M.a.R., M.J.L.); Department of Clinical Physiology, Nuclear Medicine, and PET, Rigshospitalet, Copenhagen, Denmark (I.L., J.C.); Section of Radiation Oncology, Skåne University Hospital, Lund, Sweden (S.E.).
authors.forename: Ian
authors.initials: I
authors.lastname: Law
authors.affiliation: Department of Oncology, Section of Radiotherapy, Rigshospitalet, Copenhagen, Denmark (P.M.a.R., J.C., S.A.E., M.J.L., L.O.); Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark (P.M.a.R., M.J.L.); Department of Clinical Physiology, Nuclear Medicine, and PET, Rigshospitalet, Copenhagen, Denmark (I.L., J.C.); Section of Radiation Oncology, Skåne University Hospital, Lund, Sweden (S.E.).
authors.forename: Lars
authors.initials: L
authors.lastname: Ohlhues
authors.affiliation: Department of Oncology, Section of Radiotherapy, Rigshospitalet, Copenhagen, Denmark (P.M.a.R., J.C., S.A.E., M.J.L., L.O.); Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark (P.M.a.R., M.J.L.); Department of Clinical Physiology, Nuclear Medicine, and PET, Rigshospitalet, Copenhagen, Denmark (I.L., J.C.); Section of Radiation Oncology, Skåne University Hospital, Lund, Sweden (S.E.).
authors.forename: Silke
authors.initials: S
authors.lastname: Engelholm
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy*; D005910:Glioma / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D060787:Neoplasm Grading; D049268:Positron-Emission Tomography; D014443:Tyrosine / Q000031:analogs & derivatives; D055815:Young Adult
chemical_list: C117289:O-(2-fluoroethyl)tyrosine; D014443:Tyrosine
keywords: FET-PET; MRI; glioma; radiation therapy; target definition