This issue provides a complete update on PET imaging of lymphoma, starting with a clinical assessment of lymphoma and the role of medical imaging. The role of structural imaging in lymphoma is then discussed.  From a Nuclear Medicine perspective, FDG-PET in lymphoma is reviewed, as is the role of FDG-PET in pediatric lymphoma.  Next, the role of non-FDG tracers in lymphoma is reviewed.  Other articles cover the role of fMRI and optical imaging in lymphoma, the role of diffusion-weighted MRI in lymphoma, FDG-PET in personalization of therapy in patients with lymphoma, and PET and radiation oncology in lymphoma.