Ultrasound Elastography for the Assessment of Sarcopenia

Background: Sarcopenia is an age-related syndrome characterized by progressive loss of skeletal muscle mass and strength, representing a major contributor to disability and increased mortality in older adults. Current diagnostic frameworks increasingly emphasize muscle quality alongside quantity, creating a clinical need for bedside tools that can objectively assess muscle mechanical properties. Shear-wave elastography (SWE), an ultrasound-based technique that quantifies muscle stiffness, has emerged as a promising biomechanical biomarker of muscle quality. Aim: This narrative review evaluates the evidence supporting SWE for assessing muscle quality and its association with aging, sarcopenia, and functional outcomes. Methods: We searched PubMed, Embase, and Web of Science (from January 2010 to December 2025) using terms related to elastography and sarcopenia. Based on relevance and methodological quality, approximately 50 key studies were selected for in-depth discussion and synthesis. Synthesis: Observational studies consistently demonstrate that SWE detects age-related reductions in muscle stiffness, which correlate significantly with declines in muscle strength and physical performance. Unlike conventional B-mode ultrasound, which primarily provides morphological parameters, SWE directly reflects intrinsic tissue mechanics, enabling more direct assessment of muscle quality. In high-risk populations such as patients with type 2 diabetes, reduced muscle stiffness is also associated with sarcopenia and poor functional outcomes. However, reported stiffness trends with aging remain heterogeneous, and validated diagnostic thresholds are lacking. Stiffness changes vary by muscle group, acquisition protocol, and loading state. Clinical implementation is currently limited by inter-device variability, operator dependence, and sensitivity to muscle loading conditions. Conclusions: Current evidence suggests that SWE holds promise as an adjunctive research tool for assessing muscle quality and risk stratification, but it is not yet ready for standalone clinical diagnosis due to methodological heterogeneity, lack of validated cutoffs, and limited longitudinal data. Future large-scale, longitudinal, multicenter studies with standardized protocols are needed to establish its definitive diagnostic utility.