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Purpose 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.

Patients and 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 …