Quantifying symmetry in mandibular condyle motion: a real-time MRI approach

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Orthodontics

Background:

• Temporomandibular joints (TMJs) are crucial for jaw function, requiring synergistic movement.
• Real-time magnetic resonance imaging (RT-MRI) visualizes mandibular condyle motion but its symmetry assessment utility is underexplored.
• This study evaluates the consistency of TMJ symmetry assessments using RT-MRI data.

Purpose of the Study:

• To identify optimal methods for assessing condylar pathway symmetry using RT-MRI.
• To compare the consistency of symmetry assessments from raw image series, 3D trajectories, and quantitative parameters.
• To determine the reliability of different parameters and planes for TMJ motion analysis.

Main Methods:

• 18 volunteers underwent 2D RT-MRI in sagittal and axial planes.
• Mandibular condyles were segmented using a neural network for quantitative analysis.
• Symmetry parameters (displacement, amplitude, latency, velocity) were extracted; 3D trajectories were generated.
• Qualitative visual scoring by experts and quantitative correlation analyses (Cohen's kappa, Spearman's test) were performed.

Main Results:

• The axial plane showed higher intra-observer (κ=0.68) and inter-observer (κ=0.44) agreement than the sagittal plane (κ=0.51, 0.20).
• Inter-planar correlations were weak to moderate (ρ=0.21-0.48).
• Latency demonstrated the strongest correlation among temporal parameters.

Conclusions:

• Latency is the most robust temporal parameter for TMJ symmetry assessment in this dataset.
• The axial plane offers greater consistency for both quantitative and qualitative symmetry analysis via RT-MRI.
• Axial plane analysis may be preferable for evaluating TMJ motion symmetry.