Shear wave elastography (SWE) estimates shear modulus in muscle. This is interpreted as an index of muscle stiffness, but depends on muscle characteristics. This study evaluated relationship between shear modulus and myoelectric activity of lumbar multifidus and longissimus muscles to assess its validity. Intramuscular electromyography (EMG) of multifidus (deep [DM], superficial [SM] fibres) at L4/5, longissimus [LG] at L2, were recorded in nine healthy participants. Participants performed isometric trunk extension in side-lying from 0 to 30% maximal voluntary contraction (MVC) with EMG amplitude feedback. Using SWE, two regions of interest (ROI) were investigated in each muscle. Generally, shear modulus was moderately correlated with root mean squared (RMS) EMG (r = 0.50–0.78). Univariate and multiple regression analyses showed ultrasound/SWE features of ‘B-mode quality’ (24.5%), ‘%Void pixels’ (17.9%) and ‘Connective tissue’ (16.2%) explained most variation in the shear modulus/EMG relationship. Regression prediction scores generated using imaging features were correlated with r-coefficients of shear modulus/EMG relationship. When analysis was restricted to high quality data (i.e., regression prediction score above an a priori defined threshold), the shear modulus/EMG relationship increased to r = 0.70–0.96. Although a linear relationship between shear modulus/EMG was confirmed, supporting validity of SWE measures in anatomically distinct back muscles, this depends on image quality.

剪切波弹性成像（SWE）估计肌肉中的剪切模量。这被解释为肌肉僵硬的指标，但取决于肌肉特性。本研究评估了腰椎多裂肌和经肌的剪切模量与肌电活动之间的关系，以评估其有效性。在9名健康参与者中，记录了L4 / 5处的多纤维（深[DM]，浅层[SM]纤维），L2的长肌[LG]的肌内肌电图（EMG）。参与者以EMG振幅反馈从0到30％的最大自主收缩（MVC）侧卧进行等距躯干伸展。使用SWE，在每个肌肉中研究了两个感兴趣的区域（ROI）。通常，剪切模量与均方根（RMS）EMG呈中等相关性（r = 0.50–0.78）。单变量和多元回归分析显示超声/ SWE特征为“ B型质量”（24.5％），“％空隙像素”（17.9％）和“结缔组织”（16.2％）解释了剪切模量/ EMG关系的大部分变化。使用成像特征生成的回归预测得分与剪切模量/ EMG关系的r系数相关。当分析仅限于高质量数据时（即回归预测得分高于先验定义的阈值），剪切模量/ EMG关系增加到r = 0.70–0.96。尽管证实了剪切模量/ EMG之间的线性关系，但在解剖学上不同的背部肌肉中，SWE量度的有效性得到支持，但这取决于图像质量。