Positron Emission Tomography in the Diagnosis and Monitoring of Lymphomas

Currently, 18F FDG-PET and 18F FDG-PET/CT are widely used for diagnosis and monitoring of lymphomas. The majority of aggressive lymphomas are characterized by high glycolytic activity, which enables the visualization by using 18F FDG-PET/CT. The use of PET/CT makes it possible to clarify the stage of the disease in 10–30 % of patients, with additional tumor sites typical for advanced stage of lymphomas, which in turn effects on treatment and disease prognosis. The 18F FDG-PET/CT has the advantage over other methods of radiation diagnosis in detecting bone marrow lesions in patients with lymphomas. It has been shown that 18F FDG-PET/CT performed at early stages of chemotherapy allows differentiating patients with favorable lymphoma, which is sufficient for standard therapy and high-risk patients who require more intensive treatment with high-dose regimens of chemotherapy. After completion of therapy over 60 % of patients with HL and 40 % with aggressive non-Hodgkin’s lymphomas, have residual masses containing necrotic and/or fibrotic tissue and residual neoplastic cells. 18F FDG-PET and 18F FDG-PET/CT has been shown to be useful in identifying residual masses in 30–64 % of patients, by demonstration of persistent metabolic activity on FDG-PET. Between 62–100 % of patients with residual FDG-positive masses have been shown to relapse after first-line chemotherapy. Identification of patients with partial response to chemotherapy indicates the need for continued treatment. New radiopharmaceuticals for the diagnosis of lymphoma and evaluation of therapy effectiveness are developed. Such promising radiopharmaceuticals are 18F fluorothymidine, a biomarker of cellular proliferation and Ga-68 CXCR4, a chemokine receptor imaging biomarker.