Aims To compare the diagnostic accuracy of 18F-fluorodeoxyglucose (18F-FDG)- and 18F-fluoride-positron emission tomography/computed tomography (PET/CT) for detecting prosthetic joint infection (PJI). Methods Eighty-eight patients with symptomatic total hip (THA, n = 45) or knee arthroplasties (TKA, n = 43) who underwent both 18F-FDG- and 18F-fluoride-PET/CT within 30 days were retrospectively analysed. The standardised uptake values (SUVmax) were measured around each component. Infection status was determined according to EBJIS criteria and classified as “confirmed” or “likely” in 19 (21.6%) patients. Diagnostic accuracy was evaluated by measuring median SUVmax values with interquartile ranges (IQR) and by calculating the Area Under the Receiver Operating Characteristic Curve (AUC) with 95% confidence intervals (CI). Intra- and interobserver reliability were evaluated by intraclass correlation coefficients (ICC). Results 18F-FDG-PET/CT showed significantly higher SUVmax values around infected than non-infected components, except for THA cups: THA cups 3.9 (IQR 2.4–9.6) vs 2.9 (IQR 2.2–3.6; p = 0.66), THA stems 4.5 (IQR 3.3–5.9) vs 2.6 (IQR 2.0–3.6; p = 0.01), femoral TKA components 4.0 (IQR 2.8–5.8) vs 2.3 (IQR 1.6–2.9; p = 0.02), tibial TKA components 5.5 (IQR 4.2–7.7) vs 2.6 (IQR 2.1–3.7; p < 0.001). For 18F-fluoride-PET/CT, significant differences were found only in tibial TKA components. AUC values for 18F-FDG ranged from 0.91 (95% CI 0.81–1.00) for tibial TKA components to 0.55 (95% CI 0.27–0.83) for THA cups. Corresponding AUCs for 18F-fluoride were lower throughout. Intra-observer reliability was excellent for THA cups (ICC = 0.999), THA stem (0.983), and tibial TKA component (0.974), and fair for femoral TKA components (0.775). Conclusion 18F-FDG-PET/CT provided superior discrimination between infected and non-infected arthroplasty components compared with 18F-fluoride, achieving AUCs above 0.76 for all sites except THA cups. 18F-FDG should therefore be the preferred tracer in PET/CT for suspected PJI.
Sköld et al. (Thu,) studied this question.