title: Comparison of C-11 methionine and C-11 choline for PET imaging of brain metastases: a prospective pilot study.
abstract: OBJECTIVE
  The aim of the study was the comparison of C-11 methionine (MET) and C-11 choline (CHO) in the positron emission tomography (PET) imaging of brain metastases in correlation to the histopathology findings in stereotactic biopsy.
  
  
  METHODS
  In all, 8 patients underwent MET and CHO PET and magnetic resonance imaging, in 7 of these, the metastases were previously treated by radiation therapy. Histopathologic diagnosis was made for each patient by frame-based stereotactic serial biopsy. Standardized uptake values of tumor uptake and lesion-to-normal brain tissue ratios (LNRs) of the lesions were determined. LNRs for each tracer were compared with the histopathology findings and follow-up.
  
  
  RESULTS
  In 6 patients, biopsy revealed viable metastases, 1 patient suffered from tumor recurrence in follow-up and 1 patient was tumor free in biopsy and follow-up. In the last mentioned patient, LNR was the lowest determined in all patients for CHO, but not for MET. Mean standardized uptake values of the lesions were in median 1.8 for MET and 1.1 for CHO, median LNRs were 1.5 for MET and 6.6 for CHO. LNRs for CHO were significant higher than those for MET (P = 0.007).
  
  
  CONCLUSIONS
  In the direct comparison to the well-established amino acid tracer MET, CHO seems to be promising for the imaging of brain metastases because of significantly higher LNRs in tumor tissue compared with MET without evidence for a lower specificity of CHO uptake.
authors.affiliation: Clinic for Nuclear Medicine, University Hospital Freiburg, Germany. christof.rottenburger@uniklinik-freiburg.de
authors.forename: Christof
authors.initials: C
authors.lastname: Rottenburger
authors.forename: Michael
authors.initials: M
authors.lastname: Hentschel
authors.forename: Thomas
authors.initials: T
authors.lastname: Kelly
authors.forename: Michael
authors.initials: M
authors.lastname: Trippel
authors.forename: Ingo
authors.initials: I
authors.lastname: Brink
authors.forename: Thomas
authors.initials: T
authors.lastname: Reithmeier
authors.forename: Philipp Tobias
authors.initials: PT
authors.lastname: Meyer
authors.forename: Guido
authors.initials: G
authors.lastname: Nikkhah
mesh_terms: D000328:Adult; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary* / Q000601:surgery; D002250:Carbon Radioisotopes; D002794:Choline; D006801:Humans; D008715:Methionine; D008875:Middle Aged; D010865:Pilot Projects; D049268:Positron-Emission Tomography / Q000379:methods*; D011446:Prospective Studies; D013238:Stereotaxic Techniques
chemical_list: D002250:Carbon Radioisotopes; C086242:carbon-11 methionine; D008715:Methionine; D002794:Choline