Visualization of muscle mechanical properties assessed with ultrafast ultrasound imaging

Abstract

Injured and dysfunctional tissue often demonstrates abnormal mechanical properties including muscle stiffness. Muscle stiffness can be evaluated via methods such as simple palpation, myotonometry, and standard ultrasonography. Using models based on ultrasound B-mode imaging, changes in the viscoelastic properties of an individual muscle after intervention in clinical practice have been inferred, but more direct quantification of the changes would provide objective insights into these inferences and advance more detailed assessment of rehabilitation efficacy. Recently, developed ultrasound elastography has an advantage in that it is simple to use, virtually real time, mobile, does not require vibrators, and is more affordable. This new ultrasound technology has opened the possibility for objectively quantifying the stiffness of muscle belly in vivo. This technology serves as a foundation for exploring the use of muscle shear modulus as clinically relevant information for assessing the severity of musculoskeletal disorders and potential improvements due to various treatments. In this review, we describe the basic principles of ultrasound elastography techniques and review the current muscle research, including the strengths and limitations of their measurement capabilities.