Usefulness of a newly developed ultrasonic system to estimate skeletal muscle mass and muscle strength in community-dwelling older adults.

Measuring skeletal muscle mass index using bioelectrical impedance analysis or dual-energy X-ray absorptiometry is challenging for home care patients and those with implanted devices. Contrastingly, ultrasound measurement of skeletal muscle mass is a simple and non-invasive method. We aimed to investigate quadriceps muscle cross-sectional area measured using a newly developed ultrasonic muscle imaging system to serve as a diagnostic tool for sarcopenia. The cross-sectional study including 510 independent adults aged 65 years and older (180 men; median age, 75 years) was performed between October 2021 and December 2022. Quadriceps muscle cross-sectional area of the dominant leg was measured, and the average value was analyzed for correlation with body composition indices measured using the bioelectrical impedance analysis method, muscle strength and physical performance tests. Quadriceps muscle cross-sectional area showed a good correlation with skeletal muscle mass index (R = 0.78, P < 0.001), handgrip strength (R = 0.70, P < 0.001), and knee extension strength (R = 0.68, P < 0.001). This study demonstrated that quadriceps muscle cross-sectional area using a newly developed ultrasonic system shows a strong correlation with skeletal muscle mass index and muscle strength. These findings suggest that this system could be an alternative to bioelectrical impedance analysis for the diagnosis of sarcopenia.