Real-time MR elastography for viscoelasticity quantification in skeletal muscle during dynamic exercises

Area of Science:

• Biomedical Engineering
• Musculoskeletal Imaging
• Rheology

Background:

• Skeletal muscle viscoelasticity is crucial for dynamic movement.
• Quantifying these properties in real-time during exercise remains challenging.
• Magnetic Resonance Elastography (MRE) offers a non-invasive method to assess tissue stiffness.

Purpose of the Study:

• To develop and validate real-time MRE for quantifying viscoelastic parameters in skeletal muscle during dynamic exercises.
• To assess the feasibility of mapping dynamic changes in muscle properties.

Main Methods:

• Real-time MRE was implemented using a single-shot, steady-state spiral gradient-echo sequence.
• Lower-leg muscles of 15 healthy participants were imaged during isometric plantar and dorsiflexion.
• 180 consecutive maps of shear-wave speed and loss angle (φ) were reconstructed at a 5.9-Hz frame rate.

Main Results:

• Viscoelastic parameters (shear-wave speed and φ) increased with muscle activation.
• Significant changes were observed in the soleus during plantar flexion and tibialis anterior during dorsiflexion.
• Loss angle (φ) showed significant changes in 5 muscles during both exercises.

Conclusions:

• Real-time MRE enables high-resolution, real-time mapping of dynamic viscoelasticity in skeletal muscle.
• This technique provides a novel approach for in vivo functional elastography of muscles.
• It opens new avenues for studying physiological processes in soft tissues.