Compression elastography in assessment of bicep muscle stiffness with controlled pressure in healthy adults

Abstract

Background Ultrasound Shear Elastography (USE) is used to quantify the stiffness of biological tissues by measuring muscle deformation or displacement. Compression Elastography (CE) involves applying pressure to the skin using an ultrasound (US) transducer, resulting in tissue displacement, and is used to assess tissue stiffness based on the principle that compression produces strain. Methods In this study, we estimated the strain in the biceps brachialis of healthy volunteers (n=11) and patients with post-stroke spasticity (n=2). The arms were evaluated using the Tardieu scale and strain measurements were obtained using an ultrasound probe with the elbow flexed at 30°. A semi-automatic algorithm for muscle thickness measurement was employed to qualitatively measure muscle elasticity. The application of controlled pressure from an electromechanical actuator allows for strain estimation without direct intervention by an operator, thereby reducing subjectivity in the results. The main aim of this study was to utilize CE to characterize the normal range of muscle elasticity in the biceps brachialis of healthy volunteers who exhibited no changes and were rated 0 on the modified Tardieu scale. Results The normal range of strain for both healthy male and female volunteers demonstrated an acceptable deviation for each strain measurement, as the standard deviation was considered small and relatively constant (with higher values observed under maximum pressure). The proposed measurement mechanism is sensitive, allowing for the observation of strain differences between healthy and spastic muscles in both men and women. Conclusions Comparison of the average curve for the healthy group with two examples of curves from individuals with spasticity showed evident differences. Thus, it would be worthwhile to continue this research by evaluating a group of subjects with spastic muscles.