Positron Emission Tomography in Lymphoma: Comparison with Computed Tomography and Gallium-67 Single Photon Emission Computed Tomography

With the advent of positron emission tomography (PET), metabolic imaging has become a reality for tumor staging and monitoring response to therapy in lymphoma. Increased Fluorine-18 fluorodeoxyglucose ([¹⁸F]FDG) uptake in lymphomas has been well documented in the literature; it is based upon elevated glycolysis and longer residence time of FDG in malignant cells compared to most normal tissues. This suggests that in tumor staging, FDG-PET may be more sensitive and specific than the anatomic imaging modalities. Computed tomography (CT) is the standard imaging modality for the staging and restaging of lymphoma, and Gallium-67 (⁶⁷Ga) scintigraphy has played an important role in monitoring response to therapy and follow-up of patients. Published results suggest that FDG-PET is superior to ⁶⁷Ga imaging and may be equal or superior to CT for the detection of nodal as well as extranodal involvement in lymphoma.