Diagnostic value of hybrid FDG-PET/MR imaging of chronic osteomyelitis

BACKGROUND: Magnetic resonance imaging (MRI) and 2-[(18)F]-fluoro-2-deoxy-d-glucose ((18)F-FDG) Positron Emission Tomography, paired with Computed Tomography (PET/CT) are commonly used modalities in the complicated diagnostic work-up of osteomyelitis. PET/MRI is a relatively novel hybrid modality with suggested applications in bone infection imaging, based on expert opinion and previous qualitative research. (18)F-FDG PET/MRI has the advantages of reduced radiation dose, more soft tissue information, and is deemed more valuable for surgical planning compared to (18)F-FDG PET/CT. The goal of this study is to quantitatively assess the diagnostic value of hybrid (18)F-FDG PET/MRI for chronic osteomyelitis. METHODS: A retrospective analysis was performed by a nuclear medicine physician and radiologist on 36 patients with (18)F-FDG PET/MRI scans for suspected osteomyelitis. Sensitivity, specificity, and accuracy were determined with the clinical assessment by the orthopaedic surgeon (based on subsequent intraoperative microbiology or long-term follow-up) as the ground truth. Standardized uptake values (SUV) were measured and analysed by means of receiver operating characteristics (ROC). RESULTS: This first study to quantitatively report the diagnostic value of (18)F-FDG PET/MRI yielded a sensitivity, specificity, and accuracy of 78%, 100%, and 86% respectively. Area under the ROC curve was .736, .755, and .769 for the SUVmax, target to background ratio, and SUVmax_ratio respectively. These results are in the same range and not statistically different compared to diagnostic value for (18)F-FDG PET/CT imaging of osteomyelitis in literature. CONCLUSIONS: Based on the aforementioned advantages of (18)F-FDG PET/MRI and the diagnostic value reported here, the authors propose (18)F-FDG PET/MRI as an alternative to (18)F-FDG PET/CT in osteomyelitis diagnosis, if available.