The role of PET in lymphoma

Malignant lymphomas are a heterogeneous group of diseases whose treatment and prognosis depend on accurate staging and evaluation of histologic features. The conventional imaging procedure is CT; however, nuclear medicine imaging has also had a prominent role. Single-photon imaging with 67Ga-citrate has been widely used for lymphomas. PET with 18F-FDG has gained a role in the staging and follow-up of lymphomas, largely replacing gallium as the nuclear medicine study of choice. 18F-FDG PET has proved useful in the staging and follow-up of Hodgkin's disease and non-Hodgkin's lymphoma (especially more aggressive types), and the widespread use of PET/CT has also increased the sensitivity and specificity. Its usefulness for the staging of slow-growing lymphomas has not been established. After the basics of staging and classification of lymphomas have been outlined, this article will review the role of 18F-FDG PET in the management of patients with lymphoma. PET tracers other than (18)F-FDG, such as positron-emitting isotopes of gallium and the cellular proliferation marker 18F-3'-deoxy-3'-fluorothymidine, will be discussed and future directions for PET in lymphoma proposed.