Supersonic Shear Imaging Elastography in Skeletal Muscles: Relationship Between In Vivo and Synthetic Fiber Angles...

Area of Science:

• Biomechanics
• Medical Imaging
• Musculoskeletal Ultrasound

Background:

• Supersonic shear imaging (SSI) elastography is an advanced ultrasound technique used to measure tissue stiffness.
• Muscle architecture, including fiber pennation angle, influences mechanical properties.
• Understanding the relationship between pennation angle and shear modulus is crucial for accurate SSI applications in muscles.

Purpose of the Study:

• To investigate the correlation between pennation angle and shear modulus (μ) using SSI elastography.
• To compare the anisotropy of synthetic and in vivo pennate muscle fibers.
• To assess the applicability of SSI in various muscle architectures.

Main Methods:

• An Aixplorer ultrasound scanner was used to measure shear modulus (μ) in synthetic and in vivo muscle fibers.
• The probe was positioned parallel and transverse to fibers to evaluate anisotropy in the x2-x3 plane.
• The probe was inclined at various angles (0° to 36.86°) relative to the fibers in the x1-x3 plane.

Main Results:

• Shear modulus (μ) was significantly lower in both synthetic and vastus lateralis fibers when the probe was transverse versus longitudinal (P < .0001).
• For synthetic fibers, shear modulus (μ) significantly decreased with increasing probe angle in the x1-x3 plane (P < .0001).
• No significant relationship was found between pennation angle and shear modulus (μ) for in vivo gastrocnemius and vastus lateralis muscles.

Conclusions:

• The pennation angle does not influence shear modulus (μ) measurements by SSI elastography in in vivo human muscles.
• Synthetic fibers exhibit a reduction in shear modulus (μ) as pennation angle increases.
• These findings enhance the potential of SSI elastography for analyzing diverse muscle architectures in both normal and pathological states.