Usefulness of 18F-FDG PET-CT for the management of invasive fungal infections: A retrospective cohort from a tertiary university hospital

Background F-18-FDG PET-CT is a potentially useful technique to help manage invasive fungal infection (IFI), but information on this topic is scarce. Objectives To describe our experience using F-18-FDG PET-CT for IFI management. Patients/MethodsRetrospective cohort of IFI episodes in a university hospital from 2018 to 2023 with a(18)F-FDG PET-CT performed during the episode. We analysed its impact on IFI management compared to conventional imaging. ResultsThirty-five patients diagnosed with 36 episodes of IFI (52.8% moulds, 44.4% yeasts and 2.8% Pneumocystis) underwent 55 F-18-FDG PET-CT. 74.3% were immunocompromised, including 45.7% solid organ transplant recipients. Indications for F-18-FDG PET-CT were diagnostic (10.9%), staging (47.3%) and follow-up (41.8%). Altogether F-18-FDG PET-CT added value to IFI management in 50.9% episodes. In 26 patients who had both staging F-18-FDG PET-CT and conventional imaging, sites of IFI dissemination were detected in 53.8% and 19.2%, respectively. Staging F-18-FDG PET-CT unveiled occult sites in 34.6%, uncovering unknown dissemination in 19.2%. In the evaluation of endocarditis in patients with fungemia, it contributed in at least 38.5%. Follow-up F-18-FDG PET-CTs had an added value in 47.8% episodes. They were allowed to de-escalate antifungal therapy in 26.1%. There were discordant findings between F-18-FDG PET-CT and CT follow-up in 40% cases. Results Thirty-five patients diagnosed with 36 episodes of IFI (52.8% moulds, 44.4% yeasts and 2.8% Pneumocystis) underwent 55 F-18-FDG PET-CT. 74.3% were immunocompromised, including 45.7% solid organ transplant recipients. Indications for F-18-FDG PET-CT were diagnostic (10.9%), staging (47.3%) and follow-up (41.8%). Altogether F-18-FDG PET-CT added value to IFI management in 50.9% episodes. In 26 patients who had both staging F-18-FDG PET-CT and conventional imaging, sites of IFI dissemination were detected in 53.8% and 19.2%, respectively. Staging F-18-FDG PET-CT unveiled occult sites in 34.6%, uncovering unknown dissemination in 19.2%. In the evaluation of endocarditis in patients with fungemia, it contributed in at least 38.5%. Follow-up F-18-FDG PET-CTs had an added value in 47.8% episodes. They were allowed to de-escalate antifungal therapy in 26.1%. There were discordant findings between F-18-FDG PET-CT and CT follow-up in 40% cases. Conclusions Overall, F-18-FDG PET-CT added value to IFI management in more than 50% of the episodes. It increased the diagnosis of occult sites, unveiled disseminated disease missed out by conventional imaging, and contributed to diagnose or rule out endocarditis in fungemia. Follow-up F-18-FDG PET-CT helped adjust the treatment duration and deserves further study.