Muscle compression improves reliability of ultrasound echo intensity.

Abstract

Muscle echo intensity has been shown to correlate with disease status in muscle disorders, including Duchenne muscular dystrophy (DMD). We report the effect of sonographer-applied load on measurements of muscle echo intensity. Quadriceps ultrasound scans were performed on 22 healthy boys and 16 boys with DMD between the ages of 2.2 and 15.3 years. Transducer contact force was increased linearly from 1.5 to 10 N, and echo intensity was measured throughout. Echo intensity increased linearly with strain at a rate of 42 (95% confidence interval [CI]: 21-63) and 74 (95% CI: 49-98) in the healthy and DMD populations, respectively. Echo intensity reliability was moderate at low strain (intraclass correlation coefficient [ICC] = 0.82) and was improved at high strain (ICC = 0.92). Sonographer-applied load introduces error in measurements of echo intensity, but it can be minimized by measuring echo intensity at near-maximal levels of compression. Muscle Nerve 57: 423-429, 2018.