Objectives: To measure speed of sound (SoS) with a novel hand-held ultrasound technique as a quantitative indicator for muscle loss and fatty muscular degeneration.
Methods: Both calf muscles of 11 healthy, young females (mean age 29 years), and 10 elderly females (mean age 82 years) were prospectively examined with a standard ultrasound machine. A flat Plexiglas® reflector, on the opposite side of the probe with the calf in between, was used as timing reference for SoS (m/s) and ΔSoS (variation of SoS, m/s). Handgrip strength (kPA), Tegner activity scores, and 5-point comfort score (1 = comfortable to 5 = never again) were also assessed. Ultrasound parameters (muscle/adipose thickness, echo intensity) were measured for comparison.
Results: Both calves were assessed in less than two minutes. All measurements were successful. The elderly females showed significantly lower SoS (1516 m/s, SD17) compared to the young adults (1545 m/s, SD10; p < 0.01). The ΔSoS of elderly females was significantly higher (12.2 m/s, SD3.6) than for young females (6.4 m/s, SD1.5; p < 0.01). Significant correlations of SoS with hand grip strength (r = 0.644) and Tegner activity score (rs = 0.709) were found, of similar magnitude as the correlation of hand grip strength with Tegner activity score (rs = 0.794). The average comfort score of the elderly was 1.1 and for the young adults 1.4. SoS senior/young classification (AUC = 0.936) was superior to conventional US parameters.
Conclusions: There were significant differences of SoS and ΔSoS between young and elderly females. Measurements were fast and well tolerated. The novel technique shows potential for sarcopenia quantification using a standard ultrasound machine.
Key points: • Speed of sound ultrasound: a novel technique to identify sarcopenia in seniors. • Measurements were fast and well tolerated using a standard ultrasound machine. • The novel technique shows potential for sarcopenia quantification.
Keywords: Adipose tissue; Aging; Sarcopenia; Skeletal muscle; Ultrasonography.