Ultrasonography.  2017 Jan;36(1):25-32. 10.14366/usg.16003.

Shear wave elastography using ultrasound: effects of anisotropy and stretch stress on a tissue phantom and in vivo reactive lymph nodes in the neck

• Lee HY
• Lee JH
• Shin JH
• Kim SY
• Shin HJ
• Park JS
• Choi YJ
• Baek JH

• KMID: 2365573
• DOI: http://doi.org/10.14366/usg.16003

Abstract

PURPOSE
The purpose of this study was to evaluate how the anisotropy and the static stretch stress of the cervical musculature influence the measured shear modulus in a tissue-mimicking phantom and in cervical lymph nodes in vivo by using shear wave elastography (SWE).
METHODS
SWE was performed on a phantom using a pig muscle and on the middle jugular cervical lymph nodes in six volunteers. Tissue elasticity was quantified using the shear modulus and a supersonic shear wave imaging technique. For the phantom study, first, the optimal depth for measurement was determined, and then, SWE was performed in parallel and perpendicular to the muscle fiber orientation with and without strain stress. For the in vivo study, SWE was performed on the cervical lymph nodes in parallel and perpendicular to the sternocleidomastoid muscle fiber direction with and without neck stretching. The mean values of the shear modulus (meanSM) were then analyzed.
RESULTS
In the phantom study, the measured depth significantly influenced the meanSM with a sharp decrease at the depth of 1.5 cm (P<0.001). Strain stress increased the meanSM, irrespective of the muscle fiber orientation (P<0.001). In the in vivo study, the meanSM values obtained in parallel to the muscle fiber orientation were greater than those obtained perpendicular to the fiber orientation, irrespective of the stretch stress (P<0.001). However, meanSM was affected significantly by the stretch stress parallel to the muscle fiber orientation (P<0.001).
CONCLUSION
The anisotropic nature of the cervical musculature and the applied stretch stress explain the variability of the SWE measurements and should be identified before applying SWE for the interpretation of the measured shear modulus values.

Keyword

Neck; Lymph nodes; Elasticity imaging techniques; Shear wave imaging; Anisotropy; Elasticity imaging techniques

MeSH Terms

Anisotropy*
Elasticity
Elasticity Imaging Techniques*
Lymph Nodes*
Neck*
Ultrasonography*
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