Is 18 F-FDG-PET/CT an Optimal Imaging Modality for Detecting Immune-Related Adverse Events after Immune-Checkpoint Inhibitor Therapy? Pros and Cons.

Simple Summary: Recent advances in cancer therapy have spotlighted immune checkpoint inhibitors (ICIs) as a breakthrough in treating various cancers. These treatments, however, can lead to immune-related adverse events (irAEs) that mirror the body's heightened immune response, affecting multiple organs. Recognizing and managing these irAEs is critical, and imaging modalities such as ¹⁸F-FDG PET/CT have emerged as a potential tool for early detection. This review delves into the capability of ¹⁸F-FDG PET/CT to identify irAEs, exploring the patterns of metabolic activation indicative of these events. While highlighting the current utility of PET/CT scans in oncology for tracking therapy response and irAEs, the review also speculates on future directions, suggesting a potential role in refining immunotherapy strategies and enhancing patient care. The insights obtained could transform patient monitoring during ICI therapy, potentially improving outcomes by facilitating prompt management of irAEs. Immunotherapy with immune checkpoint inhibitors (ICIs) has revolutionized contemporary oncology, presenting efficacy in various solid tumors and lymphomas. However, ICIs may potentially overstimulate the immune system, leading to immune-related adverse events (irAEs). IrAEs may affect multiple organs, such as the colon, stomach, small intestine, kidneys, skin, lungs, joints, liver, lymph nodes, bone marrow, brain, heart, and endocrine glands (e.g., pancreas, thyroid, or adrenal glands), exhibiting autoimmune inflammation. ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) is commonly used in oncology for staging and assessment of therapy responses, but it may also serve as a tool for detecting irAEs. This review aims to present various patterns of metabolic activation associated with irAEs due to ICI treatment, identifiable through ¹⁸F-FDG PET/CT. It describes the advantages of early detection of irAEs, but also presents the challenges in differentiating them from tumor progression. It also delves into aspects of molecular response assessment within the context of pseudoprogression and hyperprogression, along with typical imaging findings related to these phenomena. Lastly, it summarizes the role of functional PET imaging in oncological immunotherapy, speculating on its future significance and limitations. [ABSTRACT FROM AUTHOR]