title: (11)C-methionine PET/CT and MRI of primary central nervous system diffuse large B-cell lymphoma before and after high-dose methotrexate.
abstract: OBJECTIVE
  Although the optimum treatment of primary central nervous system lymphoma (PCNSL) remains a challenge, there is increasing interest in methotrexate-based chemotherapy as an effective strategy. Here, we report evidence supporting the utility of methionine PET/CT for evaluating PCNSL disease extent and response to high-dose methotrexate therapy.
  
  
  METHODS
  Four patients newly diagnosed with diffuse large B-cell PCNSL underwent methionine PET/CT and MRI of the brain at baseline and again after completion of high-dose methotrexate combination chemotherapy. Three patients also received pretreatment FDG PET/CT, and the intervals between MRI and both PET/CTs were within 3 weeks. The results of methionine PET/CT were compared with MRI and clinical findings.
  
  
  RESULTS
  Pretreatment methionine PET/CT demonstrated clear demarcation of PCNSL tumors with high contrast in 3 patients and only faint uptake in the remaining patient, which also showed low FDG uptake. In 1 patient, methionine PET/CT displayed more tumor lesions than FDG PET/CT did. After high-dose methotrexate chemotherapy, methionine images displayed complete disappearance of abnormal uptake in all 4 patients. In 3 of the patients, posttreatment MRI and clinical follow-up corroborated findings of complete remission. In the remaining patient, MRI showed nonenhancing T2 hyperintensities in the periventricular white matter, for which the significance was inconclusive.
  
  
  CONCLUSIONS
  Methionine PET/CT may provide clinically useful information complementary to MRI for monitoring the response to systemic chemotherapy in patients with PCNSL.
authors.affiliation: Department of Nuclear Medicine, CHA Bundang Medical Center, CHA University, Seoul, Korea.
authors.forename: Su Jin
authors.initials: SJ
authors.lastname: Jang
authors.forename: Kyung-Han
authors.initials: KH
authors.lastname: Lee
authors.forename: Ji Young
authors.initials: JY
authors.lastname: Lee
authors.forename: Joon Young
authors.initials: JY
authors.lastname: Choi
authors.forename: Byung-Tae
authors.initials: BT
authors.lastname: Kim
authors.forename: Seok Jin
authors.initials: SJ
authors.lastname: Kim
authors.forename: Won Seog
authors.initials: WS
authors.lastname: Kim
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use; D001921:Brain / Q000000981:diagnostic imaging* / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D016403:Lymphoma, Large B-Cell, Diffuse / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000188:drug therapy*; D008279:Magnetic Resonance Imaging; D008297:Male; D008715:Methionine; D008727:Methotrexate / Q000494:pharmacology / Q000627:therapeutic use*; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents; C086242:carbon-11 methionine; D008715:Methionine; D008727:Methotrexate