The Value of 18F-FDG PET/CT in Diagnosis and During Follow-up in 273 Patients with Chronic Q Fever

Abstract

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 ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG-PET/CT) in chronic Q fever at diagnosis and during follow-up. Methods: All Dutch adult patients suspected of chronic Q fever who were diagnosed since 2007 were retrospectively included until March 2015 when at least one ¹⁸F-FDG-PET/CT was performed. Clinical data and results from ¹⁸F-FDG-PET/CT at diagnosis and during follow-up were collected. ¹⁸F-FDG-PET/CT scans were prospectively reevaluated by three nuclear medicine physicians using a structured scoring system. Results: In total, 273 patients with possible, probable, and proven chronic Q fever were included. Of all ¹⁸F-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 ¹⁸F-FDG-PET/CT was 23.8% and 2.1%, respectively (P = 0.001). When adding ¹⁸F-FDG-PET/CT as a major criterion to the modified Duke criteria, 17 patients (1.9-fold increase) had definite endocarditis. At diagnosis, 19.6% of ¹⁸F-FDG-PET/CT led to treatment modification. During follow-up, 57.3% of ¹⁸F-FDG-PET/CT resulted in treatment modification. Conclusion: ¹⁸F-FDG-PET/CT is a valuable diagnostic technique in diagnosis of chronic Q fever and during follow-up often leading to a change in diagnosis and/or treatment modification, also providing important prognostic information on patient survival.