Viscoelasticity-based MR elastography of skeletal muscle

Area of Science:

• Biomechanics
• Biophysics
• Medical Imaging

Background:

• Skeletal muscle viscoelasticity is crucial for function.
• Assessing muscle mechanical properties in vivo is challenging.
• Understanding changes during contraction is key for diagnosing dysfunction.

Purpose of the Study:

• To develop an in vivo multifrequency MRE protocol for human skeletal muscle.
• To investigate the viscoelastic properties of muscle in relaxed and contracted states.
• To establish a baseline for future assessments of muscular dysfunction.

Main Methods:

• Developed a multifrequency MRE protocol for in vivo human skeletal muscle.
• Applied low-frequency shear vibrations (25-62.5 Hz) to femoral muscles.
• Used the springpot model to derive viscoelastic constants (μ and α) from complex shear modulus dispersion.

Main Results:

• Shear elasticity (μ) significantly increased from 2.68 ± 0.23 kPa (relaxed) to 3.87 ± 0.50 kPa (contracted).
• The viscoelastic constant α varied with muscle load, indicating altered mechanical network geometry.
• Demonstrated changes in muscle rheology between relaxed and contracted states.

Conclusions:

• The developed MRE protocol effectively measures in vivo muscle viscoelasticity.
• Muscle contraction alters both shear elasticity and mechanical network geometry.
• These rheological parameters offer potential for assessing muscular dysfunction.