3D Shear Wave Imaging in Muscle

Overview

Muscle in vivo is inherently anisotropic, but is modeled as an incompressible, elastic tranversely isotropic (TI) material. In recent years, ARFI excitation of soft tissue and subsequent 3D Shear Wave Elasticity Imaging (SWEI) shows shear wave motion in the SV and SH direction. The Nightingale lab hopes to better characterize this angle-dependent behavior and apply these methods to patients with neuromuscular disease, in hopes to produce better quantitative biomarkers for muscle health.

 

The most recent presentation on our work from IUS IEEE 2020 can be seen here:

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Link to warpwire - Anna Knight IUS IEEE 2020 Talk

 

In vivo shear wave propagation in 3D in the rectus femoris muscle, demonstrating transverse isotropy:

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rectus3slicevideo

This video shows the particle velocity of a shear wave produced in the rectus femoris muscle in vivo, with a Verasonics L7-4 transdcuer rotating around the z axis in 5 degree increments, and acquiring 36 SWEI acquistions over ~2 minutes. Although care was taken to align the transducer start position with the fiber direction as seen on B-mode, the maximum shear wave speed was found, using ellipse fitting of the SWS in all directions, to be actually 8.3 degrees rotation from the X axis. As such, the ~XZ and ~YZ planes shown here are rotated 8.3 degrees around the Z axis, to show the most accurate along and across the fibers shear wave propagation.

 

In vivo shear wave propagation in 3D in the vastus lateralis muscle, with an added imaging plane to demonstrate the presence of shear splitting:

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lateralis_4planes_showshearsplitting

This video shows the particle velocity of a shear wave produced in the rectus femoris muscle in vivo, with a Verasonics L7-4 transdcuer rotating around the z axis in 5 degree increments, and acquiring 36 SWEI acquistions over ~2 minutes. Although care was taken to align the transducer start position with the fiber direction as seen on B-mode, the maximum shear wave speed was found, using ellipse fitting of the SWS in all directions, to be actually 6.2 degrees rotation from the X axis. As such, the ~XZ and ~YZ planes shown here are rotated 6.2 degrees around the Z axis, to show the most accurate along and across the fibers shear wave propagation. Additionally, a fourth plane, is shown between the XZ and YZ plane here, (intersecting approximately with the -10 mm mark on the lat axis). This was included so as to show the shear splitting behavior present. As the wave propagates along this plane, there are two different shear wave fronts present, representing shear splitting.

 

TI Elastic Material, 45 degree tilt simulation:

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orthoxz45_3plane

This video shows Simulated 3D-SWE data in a TI elastic material with fibers oriented at a 45 degree tilt relative to the push (axial) direction. The shear moduli were 25 kPa (along) and 9 kPa (across) with the ratio of ET/EL=0.36

 

TI Elastic Material 0 degree tilt simulation:

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OrthoY_movie

This video shows Simulated 3D-SWE data in a TI elastic material with fibers oriented at a 0 degree tilt relative to the push (axial) direction. The shear moduli were 25 kPa (along) and 9 kPa (across) with the ratio of ET/EL=0.36

Related Publications

  • Knight, A. E., Trutna, C. A., Rouze, N. C., Hobson-Webb, L. D., Caenen, A., Jin, F. Q., Palmeri, M. L., & Nightingale, K. R. "Full Characterization of in vivo Muscle as an Elastic, Incompressible, Transversely Isotropic Material Using Ultrasonic Rotational 3D Shear Wave Elasticity Imaging." IEEE Transactions on Medical Imaging. 2022 41(1), 133–144. (https://doi.org/10.1109/TMI.2021.3106278)
  • Knight, A. E., Trutna, C. A., Rouze, N. C., Hobson-Webb, L. D., Palmeri, M. L., Caenen, A., & Nightingale, K. R. "Demonstration of Complex Shear Wave Patterns in Skeletal Muscle in vivo Using 3D SWEI". 2020 IEEE International Ultrasonics Symposium (IUS), 1–4. (https://doi.org/10.1109/IUS46767.2020.9251599)
  • Rouze, N. C., Palmeri, M. L., & Nightingale, K. R. "Tractable calculation of the Green’s tensor for shear wave propagation in an incompressible, transversely isotropic material. Physics in Medicine and Biology" 2020. 65(1). (https://doi.org/10.1088/1361-6560/ab5c2d)
  • Caenen, A., Knight, A. E., Rouze, N. C., Bottenus, N. B., Segers, P., & Nightingale, K. R. "Analysis of multiple shear wave modes in a nonlinear soft solid: Experiments and finite element simulations with a tilted acoustic radiation force" Journal of the Mechanical Behavior of Biomedical Materials, 107, 2020. (https://doi.org/10.1016/j.jmbbm.2020.103754)