title: Clinical benefit of 11C methionine PET imaging as a planning modality for radiosurgery of previously irradiated recurrent brain metastases.
abstract: OBJECTIVE
  Stereotactic radiosurgery with gamma knife (GK-SRS) generally improves the focal control of brain metastases. Yet in cases of focal recurrence at a previous radiation site, MRI is often imperfect in differentiating between active tumor and radiation injury. We have examined whether the use of C methionine (MET) with PET will facilitate this differentiation and improve the outcome of GK-SRS for focally recurrent brain metastases after prior treatment.
  
  
  METHODS
  Eighty-eight patients underwent GK-SRS for postirradiation recurrent brain metastases. Thirty-four patients received radiation in areas manifesting high MET uptake (PET group) in a dose-planning procedure using MET-PET/MRI fusion images. Fifty-four patients referred from other institutes received radiation based on dose planning information obtained from MRI (MRI group).
  
  
  RESULTS
  Sex, age, and the ratio of breast cancer differed significantly between the MRI and PET groups. The total irradiation volume was significantly smaller in the PET group, and the minimal irradiation dose was significantly higher. In a multivariable statistical analysis, the use of MET-PET (P = 0.02) was independently associated with prolonged overall survival after treatment, Karnofsky performance status (P = 0.002), the number of lesions (P = 0.03), and patient's sex (P = 0.02). The median survival time was significantly longer in the PET group (18.1 months) than in the MRI group (8.6 months) (P = 0.01).
  
  
  CONCLUSIONS
  11C methionine-PET/MRI fusion images for dose planning lengthened survival in patients undergoing GK-SRS for focally recurrent brain metastases.
authors.affiliation: From the *Department of Neurosurgery, Tokyo Medical and Dental University, Tokyo, Japan; †Katsuta Hospital Mito Gamma House, Hitachi-naka, Japan; ‡Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan; and §Departments of Neurosurgery, Tokyo Women's Medical University Medical Center East, Tokyo, Japan.
authors.forename: Toshiya
authors.initials: T
authors.lastname: Momose
authors.forename: Tadashi
authors.initials: T
authors.lastname: Nariai
authors.forename: Takuya
authors.initials: T
authors.lastname: Kawabe
authors.forename: Motoki
authors.initials: M
authors.lastname: Inaji
authors.forename: Yoji
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Shinya
authors.initials: S
authors.lastname: Watanabe
authors.forename: Taketoshi
authors.initials: T
authors.lastname: Maehara
authors.forename: Keiichi
authors.initials: K
authors.lastname: Oda
authors.forename: Kenji
authors.initials: K
authors.lastname: Ishii
authors.forename: Kiichi
authors.initials: K
authors.lastname: Ishiwata
authors.forename: Masaaki
authors.initials: M
authors.lastname: Yamamoto
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000556:secondary / Q000601:surgery*; D002250:Carbon Radioisotopes; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008715:Methionine; D008875:Middle Aged; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D016634:Radiosurgery / Q000379:methods*
chemical_list: D002250:Carbon Radioisotopes; D019275:Radiopharmaceuticals; D008715:Methionine