Interpretation of 2-[F]FDG PET/CT in Hodgkin lymphoma patients treated with immune checkpoint inhibitors.

The development of immunotherapy has revolutionized cancer treatment, improving the outcome and survival of many patients. Immune checkpoint inhibitors (ICIs), the most common form of immunotherapy, use antibodies to restore T-cells' anti-tumor activity. Immune checkpoint inhibitors are gaining ground in the therapeutic strategy across various cancers. Although widely used in solid tumors, ICIs have shown remarkable efficacy in patients with Hodgkin lymphoma. 2-[F]Fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET)/CT is the gold standard to stage and monitor responses in Hodgkin lymphoma. This article reviewed the use of 2-[F]FDG-PET/CT in patients with Hodgkin lymphoma treated with ICI, focusing on image interpretation for response monitoring and detecting adverse events. Key Points • Immune checkpoint inhibitors have dramatically improved the outcome of patients with cancer. Their mechanisms of action induce inflammatory processes that might translate into a high 2-[F]FDG uptake visible on 2-[F]FDG-PET/CT, requiring an adaptation of the evaluation criteria. • PET readers should be aware of new patterns of response observed with immunotherapy in assessing treatment response in HL patients. • -[F]FDG-PET/CT has an unparalleled ability of assessing tumor response, visualizing signs of immune activation as well as immune-related adverse events in a one-stop-shop examination.