title: Impact of [11C]methionine positron emission tomography for target definition of glioblastoma multiforme in radiation therapy planning.
abstract: OBJECTIVE
  The purpose of this work was to define the optimal margins for gadolinium-enhanced T(1)-weighted magnetic resonance imaging (Gd-MRI) and T(2)-weighted MRI (T(2)-MRI) for delineating target volumes in planning radiation therapy for postoperative patients with newly diagnosed glioblastoma multiforme (GBM) by comparison to carbon-11-labeled methionine positron emission tomography ([(11)C]MET-PET) findings.
  
  
  METHODS
  Computed tomography (CT), MRI, and [(11)C]MET-PET were separately performed for radiation therapy planning for 32 patients newly diagnosed with GBM within 2 weeks after undergoing surgery. The extent of Gd-MRI (Gd-enhanced clinical target volume [CTV-Gd]) uptake and that of T(2)-MRI of the CTV (CTV-T(2)) were compared with the extent of [(11)C]MET-PET (CTV--[(11)C]MET-PET) uptake by using CT--MRI or CT--[(11)C]MET-PET fusion imaging. We defined CTV-Gd (x mm) and CTV-T(2) (x mm) as the x-mm margins (where x = 0, 2, 5, 10, and 20 mm) outside the CTV-Gd and the CTV-T(2), respectively. We evaluated the relationship between CTV-Gd (x mm) and CTV-- [(11)C]MET-PET and the relationship between CTV-T(2) (x mm) and CTV-- [(11)C]MET-PET.
  
  
  RESULTS
  The sensitivity of CTV-Gd (20 mm) (86.4%) was significantly higher than that of the other CTV-Gd. The sensitivity of CTV-T(2) (20 mm) (96.4%) was significantly higher than that of the other CTV-T(2) (x = 0, 2, 5, 10 mm). The highest sensitivity and lowest specificity was found with CTV-T(2) (x = 20 mm).
  
  
  CONCLUSIONS
  It is necessary to use a margin of at least 2 cm for CTV-T(2) for the initial target planning of radiation therapy. However, there is a limit to this setting in defining the optimal margin for Gd-MRI and T(2)-MRI for the precise delineation of target volumes in radiation therapy planning for postoperative patients with GBM.
authors.affiliation: Department of Radiation Oncology, Kizawa Memorial Hospital, Minokamo, Japan. matsuo@kizawa-memorial-hospital.jp
authors.forename: Masayuki
authors.initials: M
authors.lastname: Matsuo
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Miwa
authors.forename: Osamu
authors.initials: O
authors.lastname: Tanaka
authors.forename: Jun
authors.initials: J
authors.lastname: Shinoda
authors.forename: Hironori
authors.initials: H
authors.lastname: Nishibori
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Tsuge
authors.forename: Hirohito
authors.initials: H
authors.lastname: Yano
authors.forename: Toru
authors.initials: T
authors.lastname: Iwama
authors.forename: Shinya
authors.initials: S
authors.lastname: Hayashi
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Hoshi
authors.forename: Jitsuhiro
authors.initials: J
authors.lastname: Yamada
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kanematsu
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Aoyama
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy; D003287:Contrast Media; D005260:Female; D005682:Gadolinium; D005909:Glioblastoma / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008715:Methionine; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods; D019275:Radiopharmaceuticals; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012680:Sensitivity and Specificity; D036542:Tomography, Spiral Computed / Q000379:methods; D047368:Tumor Burden; D055815:Young Adult
chemical_list: D003287:Contrast Media; D019275:Radiopharmaceuticals; C086242:carbon-11 methionine; D008715:Methionine; D005682:Gadolinium