Impact of sequence selection on postoperative MRI interpretability and artifact reduction in simulated mandibular...

This ex vivo study evaluated the diagnostic performance of different MRI sequences for postoperative imaging of simulated mandibular fractures stabilized with titanium and bioresorbable osteosynthesis materials.

Six porcine mandibles with standardized fractures of the mandibular angle, body, and parasymphysis were stabilized using titanium microplates, titanium reconstruction plates, or bioresorbable systems. All specimens underwent photon-counting computed tomography (CT) as a reference and 3 Tesla MRI, including five sequences: T1-weighted turbo spin echo (T1-TSE), DIXON-based imaging (DIXON), T1-TSE with vendor-specific artifact reduction techniques (WARP), ultrashort echo time (UTE), and slice encoding for metal artifact correction (SEMAC). Three blinded observers rated general image interpretability, fracture visibility, artifact extent, and soft- as well as hard-tissue interpretability using five-point Likert scales. Quantitative analysis included signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and two-dimensional artifact measurements.

Advanced artifact-reduction sequences outperformed conventional T1-TSE and DIXON (p < 0.001). UTE and WARP achieved the highest general image interpretability (median 5) and excellent fracture line visibility, alongside SEMAC. WARP provided the best soft-tissue interpretability (median 5), highest muscle SNR (median 207.9 vs. 74.4 for SEMAC and 51.9 for UTE; p ≤ 0.013), and highest CNR (median 184.8 vs. 59.6 for SEMAC and 23.5 for UTE; p ≤ 0.043), while UTE demonstrated superior hard-tissue SNR (median 30.0 vs. 13.2 for SEMAC; p < 0.001). SEMAC showed the greatest reduction in artifact extent (135% relative to CT vs. 209% for WARP and 220% for UTE; p ≤ 0.004). There was good inter-reader agreement (α = 0.76).

Advanced MRI sequences, such as SEMAC, UTE and WARP, substantially improved postoperative image interpretability and reduced implant-related artifacts. A tailored MRI protocol may complement CT in selected postoperative scenarios.