PET/MRI as a complement to PET/CT in chronic osteomyelitis with soft-tissue involvement: implications for surgical...

Chronic osteomyelitis with soft-tissue involvement carries high risks of recurrence and reoperation. Accurate preoperative delineation of bone and soft-tissue infection is critical but challenging with conventional imaging. [¹⁸F]fluorodeoxyglucose positron emission tomography/computed tomography ([¹⁸F]FDG PET/CT) is sensitive for osseous lesions but limited for soft tissue, while magnetic resonance imaging (MRI) provides soft-tissue detail but lacks specificity. This study evaluated whether hybrid positron emission tomography/magnetic resonance imaging (PET/MRI) could overcome these limitations and improve surgical management.

We retrospectively reviewed 52 patients with chronic osteomyelitis and soft-tissue infection (2018-2024). Patients were stratified into a combined group (PET/CT + PET/MRI, n = 10) and a standard group (PET/CT + MRI, n = 42). Imaging accuracy was compared with intraoperative findings. Twelve-month outcomes included recurrence-free survival (RFS), functional recovery [Lower Extremity Functional Scale (LEFS), Musculoskeletal Tumor Society (MSTS) score], and neurovascular complications.

PET/CT identified cortical destruction and intraosseous infection but underestimated soft-tissue involvement. PET/MRI delineated abscesses, sinus tracts, and muscle infiltration with close concordance to surgical findings and less overestimation than MRI. The combined group showed lower recurrence (10.0% vs. 35.7%), longer RFS, and superior function (LEFS 55.7 ± 7.1 vs. 48.3 ± 7.4; MSTS 19.6 ± 2.1 vs. 16.4 ± 2.4; all p < 0.05). Neurovascular complication rates were also reduced (10.0% vs. 21.4%).

PET/MRI integrated with PET/CT improved infection mapping, guided precise debridement, and was associated with reduced recurrence, better recovery, and enhanced neurovascular safety. These findings support PET/MRI as a valuable adjunct in complex chronic osteomyelitis, warranting validation in larger studies.