Three-dimensional rotational shear wave elastography for muscle characterization: Opportunities and challenges

There is great interest in characterizing the material properties of heterogeneous transversely anisotropic media such as muscle and associated connective tissue for a number of clinical conditions. For example, alterations in tissue mechanical properties are a hallmark of many chronic musculoskeletal pain disorders, such as neck and lower back pain, which are leading causes of disability worldwide. Current diagnostic criteria are based on subjective physical examination, and there is a pressing need to develop reliable and objective image-based biomarkers. Ultrasound shear wave elastography (SWE) is an attractive modality due to its suitability for use in community-based pain management clinics. However, the complex architecture and heterogeneous material properties of muscle make it challenging to develop ultrasound-based biomarkers. This talk will describe the use of 3-D rotational SWE as a method for quantifying the anisotropic material properties of muscle. In this method, the ultrasound transducer is mechanically rotated at different angles and SWE images are acquired at each angle to develop a 3-D representation of the anisotropic shear wave propagation speed. Results from a recent clinical study of 90 subjects with and without chronic musculoskeletal neck pain highlight the opportunities and challenges associated with 3-D rotational SWE in this clinical application and the need for future research in this area.