ABSTRACT
Objective:To evaluate the clinical value of musculoskeletal ultrasound in the diagnosis of sarcopenia by measuring the muscle mass and hardness of medial head of gastrocnemius.Methods:According to the diagnostic criteria of Asian Working Group for Sarcopenia(AWGS), 60 patients with sarcopenia were selected as the case group and 24 normal elderly people with matched age as the control group.Two dimensional gray-scale ultrasound was used to measure the muscle thickness, pinnate angle and fascicle length of the right gastrocnemius muscle, and the shear wave elastography was used to measure the Young's modulus(the dynamic stiffness)of the muscle in the states of relaxation and contraction, respectively.The differences of various ultrasound parameters between the two groups were compared, and the relativity of muscle thickness of the medial head of the right gastrocnemius muscle, the feather horn, fascicle length in the case group with sarcopenia was analyzed.The value of the ultrasound measurements in predicting sarcopenia was analyzed by ROC curve.Results:The muscle thickness(10.0±2.1)mm, pinnate angle(16.9±3.2)°, fascicle length(30.5±3.2)mm and Young's modulus[(11.5±2.2)kPa in relaxation state, (23.2±4.0)kPa in contraction state]of the right gastrocnemius muscle were lower in the sarcopenia group than in the control group with matched age[(14.8±1.2)mm, (21.7±2.5)°, (34.2±1.6)mm, (15.0±1.5)kPa, (30.6±2.8)kPa, respectively, t=10.454, 3.612, 5.631, 6.922, 8.173, all P<0.05]. The Young's modulus value was lower in relaxed state than in the contraction state.Pearson correlation analyses showed the muscle thickness and Young modulus were negatively correlated with the age( r=-0.307, -0.285, P<0.05), and the muscle thickness was positively correlated with the limb skeletal muscle mass index( r=0.838, 0.761, P<0.01). Logistic regression analysis showed the muscle thickness and Young's modulus were significantly correlated with sarcopenia( OR=4.576, 3.867). ROC analysis revealed that the threshold values of ultrasound examination of the right gastrocnemius muscle medial head for diagnosis of sarcopenia were as follows: muscle thickness of 11 mm, pinnate angle of 17 degrees, fascicle length of 32 mm, Young modulus at the relaxation state of 12.4 kPa.The sensitivity and specificity of muscle thickness for diagnosis of sarcopenia were the best(86.7% and 100%, respectively)as compared with other measurements. Conclusions:The measurement of muscle mass and muscle hardness of the medial head of gastrocnemius by ultrasound can reflect the decrease of muscle mass and muscle hardness quantitatively, and provide imaging indicators for the prediction of sarcopenia.