Emerging Trends in Radionuclide Imaging of Infection and Inflammation in Pediatrics: Focus on FDG PET/CT and Immune Reactivity

The most common indication for 18F-FDG PET/CT is tumor imaging, which may be performed for initial diagnosis, staging, therapeutic response monitoring, surveillance, or suspected recurrence. In the routine practice of pediatric nuclear medicine, most infectious, inflammatory, and autoimmune processes that are detected on 18F-FDG PET/CT imaging -except for imaging in fever or inflammation of unknown origin -are coincidental and not the main indication for image acquisition. However, interpreting these coincidental findings is of utmost importance to avoid erroneously attributing these findings to a neoplastic process. We review the recent literature on fever of unknown origin as well as inflammation of unknown origin in pediatrics and then focus on the 18F FDG PET/CT imaging findings seen in two specific entities with increased immune reactivity: hemophagocytic lymphohistiocytosis syndrome and the immune -related adverse events associated with checkpoint inhibitors. We will subsequently close with two sections highlighting related topics and relevant references for further reading.Semin Nucl Med 53:18-36 (c) 2022 Elsevier Inc. All rights reserved.

Automated summary

The most common indication for 18F-FDG PET/CT is tumor imaging, but in pediatric nuclear medicine, most coincidental findings of infectious, inflammatory, and autoimmune processes are not the main indication and it is important to interpret these findings correctly. This review focuses on recent literature on fever of unknown origin and inflammation of unknown origin in pediatrics, as well as the PET/CT imaging findings in two specific diseases with increased immune reactivity.