The Diagnostic Value of FDG-PET in Patients with Suspected Chronic Bone Infection

Abstract

Background: Diagnosing an active deep bone infection is difficult as the cardinal clinical signs of infection are often discrete in case of a low-grade infection such as chronic osteomyelitis (COM). Recent studies have demonstrated that fluoro-deoxy-glucose (FDG) positron emission tomography (PET) has an excellent diagnostic accuracy in chronic osteomyelitis. The aim of the present study was to evaluate the diagnostic accuracy of FDG-PET for patients with suspected chronic osteomyelitis. Methods: A retrospective study of patients who were evaluated with FDG-PET for suspected chronic osteomyelitis was performed. Results: In the period between February 1999 and October 2004 twenty patients were identified; 15 men and five women, aged between 12 and 79 years (median age, 43 years). The reference test for the diagnostic imaging procedure was in thirteen patients preoperative microbiological culture whereas seven patients had clinical follow-up for at least six months (mean 2.4 years). Nine bone infections (9/11) were correctly identified by FDG-PET (TP). Two bone infections were missed (FN). In eight patients (8/9), a suspicion for osteomyelitis was correctly invalidated (TN), in six patients a soft-tissue infection could be delineated and in two patients no site of infection was found. In one patient, osteomyelitis in the femoral condyl was suggested by FDG-PET whereas histological analyses demonstrated a sterile giant cell reaction (FP). Sensitivity, specificity, and accuracy were 82 %, 89 %, 85 %, respectively. The positive and negative predictive values (PPV and NPV) were 90 % and 80 %, respectively, with a corresponding prevalence of 55 %. Conclusions: In conclusion, we have found a relatively high diagnostic accuracy of FDG-PET in the evaluation of patients with a suspected chronic bone infection. However, FDG-PET is currently not widely available and is associated with relatively higher costs. Therefore, future cost-effectiveness studies have to determine whether the additional diagnostic value of this technique alters patient management.