The Value of F-FDG PET/CT in Diagnosis and During Follow-up in 273 Patients with Chronic Q Fever.

In 1%-5% of all acute Q fever infections, chronic Q fever develops, mostly manifesting as endocarditis, infected aneurysms, or infected vascular prostheses. In this study, we investigated the diagnostic value of F-FDG PET/CT in chronic Q fever at diagnosis and during follow-up. All adult Dutch patients suspected of chronic Q fever who were diagnosed since 2007 were retrospectively included until March 2015, when at least one F-FDG PET/CT scan was obtained. Clinical data and results from F-FDG PET/CT at diagnosis and during follow-up were collected. F-FDG PET/CT scans were prospectively reevaluated by 3 nuclear medicine physicians using a structured scoring system. In total, 273 patients with possible, probable, or proven chronic Q fever were included. Of all F-FDG PET/CT scans performed at diagnosis, 13.5% led to a change in diagnosis. Q fever-related mortality rate in patients with and without vascular infection based on F-FDG PET/CT was 23.8% and 2.1%, respectively ( = 0.001). When F-FDG PET/CT was added as a major criterion to the modified Duke criteria, 17 patients (1.9-fold increase) had definite endocarditis. At diagnosis, 19.6% of F-FDG PET/CT scans led to treatment modification. During follow-up, 57.3% of F-FDG PET/CT scans resulted in treatment modification. F-FDG PET/CT is a valuable technique in diagnosis of chronic Q fever and during follow-up, often leading to a change in diagnosis or treatment modification and providing important prognostic information on patient survival.