Diagnosis Value of 18 F-FDG PET/CT versus Whole Body CT Scan in Management of Patients with Fever of Unknown Origin, Inflammatory Syndrome of Unknown Origin or Episodic Fever of Unknown Origin: A Comparative Multicentre Prospective Clinical Trial

Background: 18F-fluorodesoxyglucose positron emission tomography (PET/CT) takes an increasing part in the management of patients with fever of unknown origin (FUO), inflammation of unknown origin (IUO) and episodic fever of unknown origin (EFUO). However, its costs keep on substantial and may have accessibility issues. Studies regarding the place of Whole Body Computed Tomography (WBCT) in this condition are outstanding. Methods: A prospective, multicentre study was driven to test the diagnosis value of PET/CT compared to WBCT in patients with FUO, IUO or EFUO. Diagnostic orientation (DO), diagnostic contribution (DC) and time to diagnosis of both imaging resources were evaluated. Logistic regression was used to define diagnostic's predictive parameters and to delimit a patient profile displaying the highest DC of PET/CT. Findings: 103 patients were included, 35 FUO, 35 IUO and 33 EFUO. Diagnosis, performed in 58 patients (56·3%), was mostly represented by non-infectious inflammatory diseases (n=35/58, 60·3%) in patients with FUO and IUO, while patients with EFUO had mainly miscellaneous diseases (n=6/14, 42.8%). PET/CT both showed higher DO (28·2% vs 7·8%, p 30 mg/L (p=0·03) were associated with obtaining a diagnosis. PET/CT was more relevant in patients over 60 years (p=0·003) and in those with a duration of symptoms shorter than 35 months (p=0·004). Interpretation: PET/CT performs better DO and DC than WBCT, especially in patients with FUO and IUO, and reduces the time to diagnosis in these populations. Elderly patients and those with a duration of symptoms shorter than 3 years are the ones who most benefit from PET/CT. Trial Registration: NCT01200771. Funding Statement: The study was sponsored by public grants from the French Ministry of Health. Declaration of Interests: The authors declare that they have no competing interests. Ethics Approval Statement: The trial was approved by all local ethical committees. All patients provided written informed consent before entering the study.