The texture anisotropy index to differentiate healthy and disordered muscles with ultrasound

Dubois et al. (2018) introduce local pattern texture anisotropy as a novel parameter, expressed in a texture anisotropy index (TAI), to differentiate healthy and disordered muscles and to gauge the severity of muscle impairments based on B-mode ultrasound images.
Normal ultrasound images obtained along the longitudinal axis of the muscle reveal the perimysium as parallel echogenic lines on a background of the hypo echoic muscle fascicles. This main orientation of the signal can be easily identified with the eye at multiple scales. This phenomenon may be referred to as local texture anisotropy. In the normal muscle, local texture anisotropy may thus be considered high. As degenerative muscle changes intensify (i.e., increase fat content and fibrosis), this preferential orientation of the signal may be disrupted; that is, the local texture anisotropy is reduced.

The authors suggest that the TAI may be promising as an additional texture-based approach for quantitative muscle ultrasound imaging in order to diagnose, characterize and follow-up of muscle alterations using ultrasound imaging. More research and testing needs to be done before implementing it in clinical practice.