18F FDG PET/CT plays an important role in the investigation of fever of unknown origin (FUO), particularly after failure of conventional investigations to identify the source. However, its diagnostic yield is highly influenced by a wide range of factors including patient preparation, physiological variant, and treatment related factors. This review aims to provide an overview of the most common causes experienced in clinical practice, and how to avoid common pitfalls that may affect scan interpretation. For instance, elevated blood glucose levels, prolonged steroid therapy and recent interventions may reduce scan sensitivity, while artefacts from injection sites and brown fat uptake may mimic sites of disease. Careful preparation - including dietary modification, activity restriction and appropriate access selection - combined with clinical correlation and review of non-attenuation corrected images enhances interpretation, and as always, multidisciplinary discussions remain key.
Nawwar et al. (2025) studied this question.