Schonau V, et al. - A prospective study is done to explore the value of ¹⁸F-fluorodesoxyglucose positron emission tomography (¹⁸F-FDG-PET) in identifying the cause of fever of unknown origin (FUO) and inflammation of unknown origin (IUO). The current study showed that the ¹⁸F-FDG-PET/CT scanning is helpful in finding out the correct diagnosis in over half of the cases presenting with FUO and IUO. The absence of intermittent fever, higher age and raised C-reactive protein (CRP) level increase the likelihood for a diagnostic ¹⁸F-FDG-PET/CT.

Methods

• For this research, they designed a prospective study.
• In this study, they tested diagnostic utility of ¹⁸F-FDG-PET/CT in a large cohort of patients with FUO or IUO and to characterize parameters that increase the likelihood of diagnostic ¹⁸F-FDG-PET/CT.
• Patients with FUO or IUO received ¹⁸F-FDG-PET/CT scanning in addition to standard diagnostic work-up.
• ¹⁸F-FDG-PET/CT results were classified as helpful or non-helpful in establishing final diagnosis.
• Binary logistic regression was utilized to recognize clinical parameters related to a diagnostic ¹⁸F-FDG-PET/CT.

Results

• In this study, total 240 patients were enlisted.
• Out of these 240 patients, 72 with FUO, 142 with IUO and 26 had FUO or IUO previously (exFUO/IUO).
• In 190 patients (79.2%) diagnosis was established.
• The leading diagnoses were adult-onset Still’s disease (15.3%) in the FUO group, large vessel vasculitis (21.1%) and polymyalgia rheumatica (18.3%) in the IUO group and IgG4-related disease (15.4%) in the exFUO/IUO group.
• In 136 patients (56.7% of all patients and 71.6% of patients with a diagnosis), ¹⁸F-FDG-PET/CT was positive and helpful in finding the diagnosis.
• Predictive markers for a diagnostic ¹⁸F-FDG-PET/CT were age more than 50 years (p=0.019), C-reactive protein (CRP) level over 30 mg/L (p=0.002) and absence of fever (p=0.001).