Intraoperative C-arm CBCT versus early postoperative MRI for the assessment of fracture reduction and osteosynthesis material positioning in cranio-maxillofacial trauma surgery

PURPOSE: To compare intraoperative C-arm cone-beam computed tomography (CBCT) with dedicated in-house-optimized magnetic resonance imaging (MRI) protocols, including CT-like and metal artifact reduction sequences (MARS), using a novel 15-channel coil for the evaluation of fracture reduction, osteosynthesis material positioning, and the depiction of plates and screws. METHODS: Fifteen patients (13 men, 2 women; median age, 32 years; range, 18-65 years) with acute cranio-maxillofacial fractures underwent surgical treatment with intraoperative CBCT, followed by early postoperative MRI within 36 h. MRI protocols included 3D ultrashort echo time (UTE), slice-encoding for metal artifact correction (SEMAC), and 3D double-echo steady-state (DESS). Two independent maxillofacial surgeons performed qualitative and quantitative evaluations of fracture reduction, osteosynthesis material positioning, and implant morphology using a 5-point visual scale (5 = best; 1 = non-assessable) and dimensional measurements. Descriptive statistics were calculated, and inter-reader agreement was assessed using weighted kappa (κ) and intraclass correlation coefficients (ICC). RESULTS: UTE and SEMAC sequences provided excellent CT-like performance in visualizing fracture reduction and implant positioning (median 5, IQR 5-5 and 4-5, respectively), with minimal absolute differences in quantitative measurements and substantial to almost perfect inter-reader agreement (κ = 0.75-1.0; ICC = 0.89-0.99; all p < 0.001). In contrast, DESS demonstrated limited utility for assessing metallic implants due to pronounced signal voids and susceptibility artifacts. CONCLUSION: UTE and SEMAC provide high-quality, radiation-free imaging for evaluating fracture reduction and osteosynthesis material in cranio-maxillofacial trauma. These techniques demonstrate comparable diagnostic performance to intraoperative CBCT in a postoperative setting. They may serve as a radiation-free alternative for perioperative imaging in younger patients with anticipated repeated imaging needs, pending prospective intraoperative validation. TRIAL REGISTRATION NUMBER: Swiss National Clinical Trials Portal: SNCTP000006343, ClinicalTrials.gov ID: NCT07012850, Registration date: May 2025.