Immersion ultrasound improves the repeatability of shear-wave elastography for measuring median nerve elasticity

Abstract

Abstract Objective To study the factors that influence the measurement of median nerve elasticity, to provide a more reproducible test for the assessment of median nerve elasticity using shear wave elasticity (SWE), and to reduce operator empirical dependence. To compare the repeatability of the median nerve elasticity measurement using immersion SWE with that using contact SWE, analyze the factors affecting SWE measurement, and provide a more repeatable method for doctors without SWE operation experience. Methods Two doctors without SWE operation experience measured the median nerve mean elastic modulus (Emean) at the same position and at different time points on the right wrist of 58 healthy volunteers using immersion and contact ultrasound methods. The intraobserver and interobserver repeatability of measurements was assessed using the interclass correlation coefficient (ICC), while the repeatability was assessed using the Bland–Altman diagram. Results The intraobserver and interobserver repeatability of the median nerve elasticity measured via contact SWE by inexperienced operators were classified as good, with ICCs of 0.633 (95% CI 0.380–0.783) and 0.552 (95% CI 0.243–0.735), respectively. The intraobserver and interobserver repeatability of the median nerve elasticity measured by immersion SWE were very good, with ICCs of 0.975 (95% CI 0.958–0.985) and 0.942 (95% CI 0.902–0.966), respectively. The intraobserver and interobserver Bland–Altman diagram of median nerve elasticity measured by immersion SWE showed that 98% of the points fell within the 95% limits of agreement. The intraobserver and interobserver Bland–Altman diagram of median nerve elasticity measured by contact SWE showed that 94% of the points fell within the 95% limits of agreement. Conclusion Immersion ultrasound can improve the repeatability of median nerve elasticity measurements by inexperienced operators.