3D ultrasound-based determination of skeletal muscle fascicle orientations

Abstract

Architectural parameters of skeletal muscle such as pennation angle provide valuable information on muscle function, since they can be related to the muscle force generating capacity, fiber packing, and contraction velocity. In this paper, we introduce a 3D ultrasound-based workflow for determining 3D fascicle orientations of skeletal muscles. We used a custom-designed automated motor driven 3D ultrasound scanning system for obtaining 3D ultrasound images. From these, we applied a custom-developed multiscale-vessel enhancement filter-based fascicle detection algorithm and determined muscle volume and pennation angle. We conducted trials on a phantom and on the human tibialis anterior (TA) muscle of 10 healthy subjects in plantarflexion (157 ± 7$$^\circ$$ ∘ ), neutral position (109 ± 7$$^\circ$$ ∘ , corresponding to neutral standing), and one resting position in between (145 ± 6$$^\circ$$ ∘ ). The results of the phantom trials showed a high accuracy with a mean absolute error of 0.92 ± 0.59$$^\circ$$ ∘ . TA pennation angles were significantly different between all positions for the deep muscle compartment; for the superficial compartment, angles are significantly increased for neutral position compared to plantarflexion and resting position. Pennation angles were also significantly different between superficial and deep compartment. The results of constant muscle volumes across the 3 ankle joint angles indicate the suitability of the method for capturing 3D muscle geometry. Absolute pennation angles in our study were slightly lower than recent literature. Decreased pennation angles during plantarflexion are consistent with previous studies. The presented method demonstrates the possibility of determining 3D fascicle orientations of the TA muscle in vivo.

Determination of muscle shape deformations of the tibialis anterior during dynamic contractions using 3D ultrasound

“…This means that 3D deformation changes can be determined between different muscle lengths during dynamic movements. By reducing the effects of movement and fixing the leg, it is possible to examine not only the external deformation of the muscle, but also its internal architecture, for which the method described in Sahrmann et al (2024) can be used. Furthermore, with our algorithm, 3D images were reconstructed if the maximum distance between two images did not exceed 25 mm.…”

“…This study presents a novel approach for determining 3D deformation of the tibialis anterior (TA) muscle during dynamic movement. The approach represents an extension of an automated 3D ultrasound system for acquisition of muscle volumes in static conditions ( Sahrmann et al, 2024 ; Sahrmann et al, 2024 ), and a sophisticated implementation of the methods employed in Sahrmann et al (2022) . By using motion capture for determination of the ankle joint angle and encoder data for recording the ultrasound probe position and orientation, each 2D ultrasound image contains a corresponding probe position/orientation and an ankle joint angle.…”