Quantification of masseter muscle deformation during palpation using MRI and image-analysis procedure

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Anatomy

Background:

• Muscle palpation is a common clinical technique.
• Quantifying deformation during palpation can offer objective insights.
• Magnetic resonance imaging (MRI) provides detailed anatomical visualization.

Purpose of the Study:

• To quantify masseter muscle deformation during palpation using MRI.
• To explore the clinical significance of objective muscle palpation measurements.
• To validate an image-analysis procedure for assessing muscle deformation.

Main Methods:

• Ten male volunteers underwent MRI scans under compressed and noncompressed conditions.
• Cross-sectional images were superimposed to measure deformation parameters.
• Key metrics included cross-sectional area, length, thickness, and anterior/posterior extension.

Main Results:

• Masseter muscle compression led to a 14% decrease in cross-sectional area and a 31% reduction in circular convolution.
• Muscle thickness decreased by 6.7 mm, while the surrounding area length increased by 11%.
• Significant anterior extension (10%) with high individual variability was observed, contrasting with smaller posterior extension (3%).

Conclusions:

• The developed MRI method successfully quantifies masseter muscle deformation.
• Compression primarily causes anterior deformation with substantial inter-individual differences.
• These findings underscore the potential of quantitative MRI in evaluating muscle biomechanics during palpation.