Role of FDG-PET/CT in the evaluation of infectious and inflammatory disease

Infectious and inflammatory diseases are amongst the most common reasons for patients to visit the hospital, often presenting with symptoms such as fever and general malaise. In most cases, physicians can establish the correct diagnosis by recognizing guiding symptoms or conventional diagnostics. Some patients, however, may not exhibit any guiding symptoms, or may be suspected of multiple potential sources of infection. Especially in patients with bacteremia of unknown origin, it is of vital importance to identify the infection focus as soon as possible, as this allows targeted treatment and reduces morbidity and mortality. 18F-FDG-PET/CT is a nuclear imaging technique that allows visualization of glucose uptake throughout the entire body. As most inflammatory diseases and infection foci exhibit increased glucose uptake, it is a very promising technique in patients who are suspected of such a disease. The research in this thesis was aimed at exploring the added value of FDG-PET/CT in these patients. In patients with bacteremia of unknown origin, FDG-PET/CT can correctly identify the infection focus in approximately two thirds of patients. And in children with fever of unknown origin, the correct diagnosis can be established in approximately half of all patients based on FDG-PET/CT. Several factors that may affect the diagnostic sensitivity of FDG-PET/CT were analyzed as well, such as the use of antibiotics or immunosuppressants before the procedure, serum glucose level, infection parameters, and detected pathogens. Bottlenecks of FDG-PET/CT and promising new technologies are discussed as well.