Visualizing Persistent Inflammation and Occult Infections in Nonrecovering ICU Patients with [¹⁸F]FDG PET/CT: VIPER...

The use of [¹⁸F]FDG PET/CT for detection of infectious and inflammatory foci in patients admitted to the intensive care unit (ICU) has gained interest as previous retrospective studies have shown promising results. [¹⁸F]FDG PET/CT in these studies was predominantly performed in patients with prolonged organ failure. These patients often acquire an immune dysregulated state, resulting in infectious complications impairing organ recovery. Early detection of infectious or inflammatory foci in this population may improve outcomes and reduce health care costs. We aim to explore the value of [¹⁸F]FDG PET in comparison to contrast-enhanced CT (ceCT) for the detection of infectious and inflammatory foci in patients with persistent critical illness. In addition, we will assess the influence of imaging findings on therapy changes after the scans and the relation between circulating biomarkers and [¹⁸F]FDG PET/CT findings. Methods: This study protocol describes a prospective, dual-center, international, head-to-head diagnostic comparison observational cohort study. Patients admitted to the ICU for at least 7 d with organ failure and persistently increased inflammatory parameters are eligible for inclusion. After inclusion, [¹⁸F]FDG PET/CT and ceCT will be performed simultaneously between day 8 and day 15 of ICU admission. For the primary endpoint, masked and standardized assessment of the scans will be ensured by exchanging the scans cross-over between both institutions. Primary outcome will be the incidence of findings for both imaging modalities, categorizing the results as PET-positive/CT-positive, PET-negative/CT-positive, PET-positive/CT-negative, or PET-negative/CT-negative. Direct clinical availability of the scans will allow for integration into decision-making. Therapy changes within 48 h after imaging will be recorded. Additionally, a questionnaire on the expected therapy plan and known or suspected foci is completed by the attending physician before the imaging procedure to better assess the impact of imaging on decision-making. Blood samples are taken on the day of inclusion and imaging. Conclusion: This first large prospective study will explore the application of [¹⁸F]FDG PET/CT compared with ceCT to image infectious and inflammatory foci in persistent critically ill patients. This study may help define the role of [¹⁸F]FDG PET/CT imaging in the ICU environment, supporting clinicians with an additional diagnostic tool for patient management.