Reliability of Ultrasound Elastography According to Experience Level and Anatomic Location.

Backgroud: Strain elastography (SE) and shear wave elastography (SWE) are emerging techniques for evaluating the elasticity of soft tissue. This study aimed to determine interobserver and intraobserver reliability for elasticity measurements of different tissues and anatomic locations using SE and SWE.

Methods: Ten healthy adult male individuals with 20 upper extremities participated in this study. The elasticities of the wrist extensor muscle, the common extensor tendon, and supraspinatus tendon were measured. Strain ratio and shear wave velocity were measured twice by 2 different examiners (examiner 1 with over 20 years of experience in musculoskeletal sonography and examiner 2 with 1 year of experience). Interobserver and intraobserver reliability was assessed using the intraclass correlation coefficient (ICC).

Results: The 10 individuals' age ranged from 28 to 35 years. In SE, interobserver reliabilities at the 3 anatomic locations (wrist extensor muscle, common extensor tendon, and supraspinatus tendon) showed fair to moderate agreement (ICC = 0.489, = 0.076; ICC = 0.408, = 0.131; and ICC = 0.296, = 0.711, respectively). The intraobserver reliabilities of examiner 1 were moderate to substantial only at the wrist extensor muscle and the common extensor tendon (ICC = 0.563, = 0.039 and ICC = 0.702, = 0.006, respectively). In SWE, interobserver reliabilities for the wrist extensor muscle and the supraspinatus tendon were moderate to substantial (ICC = 0.756, = 0.002 and ICC = 0.565, = 0.039, respectively). The intraobserver reliabilities of examiner 1 at the 3 anatomic locations were almost perfect (ICC = 0.843, = 0.001; ICC = 0.800, = 0.001; and ICC = 0.825, = 0.001, respectively). The results of examiner 2 showed almost perfect agreement at the wrist extensor muscle (ICC = 0.886, = 0.001) and moderate to substantial agreement at the tendons of the common extensor and supraspinatus (ICC = 0.592, = 0.029 and ICC = 0.682, = 0.008, respectively).

Conclusions: SWE is a reliable method for assessing the flexibility of soft tissue, but it is affected by expertise and the specific anatomical site.