Quantitative Assessment of Muscle Morphology and Texture Features Using 3D Freehand Ultrasound
Time: Mon 2026-06-08 13.00
Location: D3, Lindstedtsvägen 5, Stockholm
Subject area: Engineering Mechanics
Doctoral student: Ruoyu Huang , Teknisk mekanik
Opponent: Christer Grönlund, Department of Radiation sciences, Umeå university, Umeå, Sweden
Supervisor: Ruoli Wang, Teknisk mekanik, Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden; Elena M. Gutierrez-Farewik, Teknisk mekanik, Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden; Matilda Larsson, Medicinteknik och hälsosystem
QC260521
Abstract
Skeletal muscle plays a central role in mobility, physical function, and overall health. Accurate quantification of skeletal muscle morphology and quality is essential for understanding muscle adaptations associated with impairment and aging, as well as for evaluating rehabilitation outcomes. This thesis investigates both the clinical application and technical advancement of three-dimensional freehand ultrasound (3DfUS) as a comprehensive tool for in vivo assessment of skeletal muscle.
In the first study, 3DfUS combined with quantitative texture analysis was used to examine muscle morphology and tissue quality in individuals with subacute stroke. In this randomized controlled study, tibialis anterior muscle volume (MV) and 3DfUS-derived texture features were evaluated before and after a four-week rehabilitation intervention. Participants were assigned to receive either only conventional rehabilitation (CR) or CR with functional electrical stimulation (FES). The results showed a significant increase in MV on the more-affected side and improved inter-limb asymmetry of MV in the FES group, whereas no significant changes were observed in the CR group. Moreover, alterations in texture features were observed on the less-affected side in the FES group, suggesting changes in muscle tissue heterogeneity. These findings support the potential of 3DfUS and texture analysis to detect muscle remodeling during the early phase of post-stroke rehabilitation.
To improve the clinical feasibility of 3DfUS, a low-cost fiducial marker-based tracking system (FM-3DfUS) was developed and validated in the second study as a practical alternative to conventional motion capture-based setups. FM-3DfUS demonstrated excellent agreement with the reference method for muscle morphological parameters of the rectus femoris muscle, including MV, fascicle length, and pennation angle. The system also showed high inter-operator reliability and inter-session repeatability, reflecting strong reproducibility across users and sessions. These findings support the feasibility of accurate 3D muscle assessment using a more clinically applicable setup, and highlight the potential of FM-3DfUS to facilitate broader implementation of quantitative muscle imaging in both research and clinical settings.