Diagnostic utility of FDG PET in prosthetic joint infection based on ICGPJI criteria.

Introduction

Prosthetic joint infection (PJI) and aseptic loosening in total hip arthroplasty (THA) can present with pain and osteolysis. The International Consensus Group on Periprosthetic Joint Infection (ICGPJI) have provided criteria for the diagnosis of PJI. The aim of our study was to analyse the utility of F18-Fluoro-deoxy-glucose (FDG) Positron Emission Tomography (PET) CT scan in the pre-operative diagnosis of septic loosening in THA based on the current ICGPJI definition of prosthetic joint infection.

Materials and method

130 painful unilateral cemented THAs were included in this prospective study. Pre- operative evaluation with inflammatory markers and aspiration were performed. F18-FDG PET scan was performed. Diagnostic utility tests were performed based on the ICGPJI criteria for PJI and three samples positive on culture alone.

Results

130 patients had FDG PET. The mean ESR, CRP and WCC were 47.83 mm/hr, 25.21 mg/l and 11.05×109/l respectively. The sensitivity, specificity, accuracy negative predictive value and false positive rate of FDG PET compared with ICGPJI criteria were 94.87%, 38.46 %, 56.38%, 94.59 % and 60.21% respectively. The false positive rate of FDG PET compared with culture alone was 77.4%. The mean follow-up was 5.17±1.12 years.

Conclusion

FDG PET has a definitive role in the pre-operative evaluation of suspected PJI. To the best of our knowledge this the first study to evaluate its utility based on ICGPJI criteria and compare it microbiology results alone. However, it has a high false positive rate. Therefore, we suggest that 18-F-FDG PET is useful in confirming the absence of infection, but if positive, may not be confirmatory of PJI.