In the evaluation of patients with skull base osteomyelitis, does 18F-FDG PET CT have a role?

Purpose To evaluate the diagnostic performance of regional fluorine-18 fluorodeoxyglucose (F-18-FDG) positron emission tomography-computed tomography (PET-CT) in patients with skull base osteomyelitis (SBO) and to compare with magnetic resonance imaging (MRI) whenever available. Materials and methods A total of 77 patients (male:female = 56:21; mean age 66.4 +/- 9.4 years) with clinically suspected SBO, who underwent regional F-18-FDG PET-CT were included in this retrospective study. F-18-FDG PET-CT images were analyzed for presence, localization and intensity of FDG uptake. Diagnostic performance of F-18-FDG PET-CT was analyzed based on histopathology, culture, and clinical/imaging follow-up. The agreement analysis between F-18-FDG PET-CT and MRI findings was performed in 56 patients. Results The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of F-18-FDG PET-CT for diagnosing SBO were 96.7, 93.3, 98.3, 87.5, and 96.1%, respectively. The average SUVmax of the lesions was 5.9 +/- 3.5. The SUVmax of the fungal lesions was lower than that of bacterial lesions with P-value of <0.001. On comparing variables like C-reactive protein, erythrocyte sedimentation rate, and SUVmax for prediction of recurrence/progression, by plotting an ROC curve, the SUVmax was found to be an independent prognostic marker. 56 out of 77 patients had undergone both F-18-FDG PET-CT and MRI. The agreement analysis between the modalities showed almost perfect agreement for delineation of soft tissue and bony involvement with kappa values of 0.82 and 0.81, respectively. Conclusion F-18-FDG PET-CT is a sensitive tool in evaluation of patients with SBO. It shows a very good agreement with the MRI. It plays a critical role in treatment response evaluation.