title: Clinical use of (11)C-methionine and (18)F-FDG-PET for germinoma in central nervous system.
abstract: OBJECTIVE
  The purpose of this study was to examine the (11)C-methionine (MET) and (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) findings of central nervous system (CNS) germinoma and the diagnostic utility of these findings.
  
  
  METHODS
  We retrospectively evaluated the cases of 10 patients who were diagnosed with CNS germinoma according to their histopathological or clinical findings. All the patients underwent pretreatment MET and/or FDG-PET scans, and the resultant images were assessed qualitatively and quantitatively. In the qualitative assessments, we used 3- and 5-grade visual scoring systems for the MET- and FDG-PET images, respectively. In the quantitative assessments, the maximal standardized uptake value (SUVmax) and the ratio of the SUVmax of the tumor (T) divided by the mean SUV for the normal white or gray matter [T/N (WM), T/N (GM)], was calculated.
  
  
  RESULTS
  The mean and SD values of SUVmax, T/N (WM), and T/N (GM) were 1.9 ± 1.4, 2.5 ± 1.3, and 1.7 ± 0.9 on MET-PET and 5.8 ± 2.2, 1.6 ± 0.5, and 0.8 ± 0.2 on FDG-PET, respectively. On MET-PET, only one lesion was not detected. On the other hand, on FDG-PET all of the lesions exhibited uptake values that were intermediate between those of the normal white matter and gray matter.
  
  
  CONCLUSIONS
  In terms of its tumor-contouring ability, MET is a good tracer for diagnosing CNS germinomas; therefore, MET-PET is considered to be useful for planning biopsies or surgery. Although FDG-PET is capable of detecting CNS germinomas, it produced insufficient image contrast in the present study. Further studies are needed before FDG-PET can be used in clinical examinations of CNS germinoma.
authors.affiliation: Department of Radiology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Shouwa-ku, Nagoya, 466-8550, Japan, y.ookouchi@med.nagoya-u.ac.jp.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Okochi
authors.forename: Takashi
authors.initials: T
authors.lastname: Nihashi
authors.forename: Masazumi
authors.initials: M
authors.lastname: Fujii
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Kato
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Okada
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Ando
authors.forename: Satoshi
authors.initials: S
authors.lastname: Maesawa
authors.forename: Shigenori
authors.initials: S
authors.lastname: Takebayashi
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Wakabayashi
authors.forename: Shinji
authors.initials: S
authors.lastname: Naganawa
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging / Q000473:pathology; D002250:Carbon Radioisotopes / Q000493:pharmacokinetics; D016543:Central Nervous System Neoplasms / Q000000981:diagnostic imaging*; D002648:Child; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D018237:Germinoma / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008715:Methionine / Q000493:pharmacokinetics; D009413:Nerve Fibers, Myelinated / Q000000981:diagnostic imaging; D036421:Nerve Fibers, Unmyelinated / Q000000981:diagnostic imaging; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D002250:Carbon Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D008715:Methionine