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Magnetic Resonance Elastography of Upper Trapezius Muscle
Emi Hojo1,2, Wiraphong Sucharit3, Saranya Jaruchainiwat4
1Centre for Reproductive Health (CRH), Institute for Regeneration and Repair (IRR), Edinburgh BioQuarter, University of Edinburgh, Edinburgh, UK.
NMR in Biomedicine
|February 27, 2025
Summary
Magnetic resonance elastography (MRE) assessed upper trapezius muscle stiffness. Positioning the actuator parallel to muscle fibers yielded higher stiffness measurements than orthogonal positioning, with no benefit above 60 Hz.
Area of Science:
- Biomechanics
- Musculoskeletal Imaging
- Medical Engineering
Background:
- Accurate measurement of muscle stiffness is crucial for diagnosing and managing musculoskeletal conditions.
- Magnetic Resonance Elastography (MRE) is a non-invasive technique for quantifying tissue stiffness.
- Optimizing MRE acquisition parameters, including actuator orientation and vibration frequency, is essential for reliable results.
Purpose of the Study:
- To investigate the impact of actuator orientation (parallel vs. orthogonal to muscle fibers) on upper trapezius (UT) muscle stiffness measurements using MRE.
- To evaluate the effect of different vibration frequencies (60 Hz, 80 Hz, 100 Hz) on UT stiffness.
- To assess the reliability and agreement of MRE stiffness measurements between two observers.
Main Methods:
- A soft, flexible tube-based actuator was used to induce vibrations in the UT muscle.
- MRE data were acquired using a 2D gradient-echo sequence on a 1.5 T MRI system.
- Wave images were generated using multimodel direct inversion (MMDI) and analyzed by two observers using manual calipers.
Main Results:
- Substantial to perfect agreement was observed between the two observers for wave quality scores and UT stiffness measurements.
- UT stiffness was significantly higher when acoustic waves propagated parallel to muscle fibers compared to orthogonal propagation (p < 0.005).
- A significant dispersion effect (stiffness increased with frequency) was observed only for parallel propagation (p < 0.05). No significant asymmetry was found between left and right UT stiffness measurements (p = 0.29).
Conclusions:
- The soft, flexible tube-based actuator is comfortable and effective for MRE of the UT muscle.
- Inducing wave propagation parallel to the principle muscle fiber direction is recommended for accurate stiffness measurements.
- A vibration frequency of 60 Hz is sufficient for reliable UT stiffness assessment, with no added benefit from higher frequencies.
