Ultrasound for Measuring the Cross-Sectional Area of Biceps Brachii Muscle in Sarcopenia

Background: Ultrasound is emerging as an effective method for measuring muscle mass in elderly people. It has been applied in numerous studies to obtain measurement of lower limbs. The study aims to explore the relationship between sarcopenia and ultrasound measurements of biceps brachii. Methods: Participants (n=179) aged over 60 years were enrolled from the first affiliated hospital of Zhejiang University. The muscle thickness (MT), cross-sectional area (CSA) and fat thickness (FT) of these participants were recorded. Spearman test and partial correlation test was used to determine the correlation between indicators. Mann-Whitney U test was performed to compare ultrasonic parameters between sarcopenia group and non-sarcopenia group. The binary logistic regression analysis was employed to detect the potential indicators and prediction equation of sarcopenia. Receiver operating characteristic (ROC) curve analysis was performed for the accuracy of equation. Results: The prevalence of sarcopenia were 16.3% and 10.8% respectively in men and women. CSA was significantly lower in sarcopenia group than non-sarcopenia group in women (P<0.05). CSA was positively correlated with skeletal muscle mass index (SMI) and grip strength (men: r=0.460, 0.433; women: r=0.267, 0.392). After controlling of age and BMI, these correlations disappeared. Binary logistic regression analysis showed that age (OR=1.149, 95%CI: 1.060-1.246; P=0.001) and CSA (OR=0.465, 95%CI: 0.225-0.963; P=0.039) was significant indicators associated with sarcopenia. Area Under Curve was 0.822 (95%CI: 0.725-0.919, P<0.001) for the prediction equation composed of age, gender and CSA for sarcopenia. Conclusion: CSA of the biceps brachii measured with ultrasound is an important indicator associated with sarcopenia.