Shear Wave Elastography (SWE) for the Evaluation of Patients with Tendinopathies.

RATIONALE AND OBJECTIVES: Shear wave elastography (SWE) has been shown to be a powerful tool to estimate tissue stiffness. The aim of this study was to compare the diagnostic accuracy of SWE to that of standard ultrasound (US) (combined use of B-mode US and power Doppler [PD] US) for diagnosing tendinopathies.

MATERIALS AND METHODS: This is a prospective institutional review board-approved study on 112 participants (mean age 42 ± 13.4 years) with chronic (>6 months) tendon pain in Achilles, patellar, or epicondylar tendons. Participants were systematically examined with US, PD, and SWE using a high-resolution linear 15 MHz probe (SuperSonic Imagine). A semiquantitative analysis of SWE color charts and a quantitative region of interest-based analysis of tendon elasticity were performed. SWE values of symptomatic and healthy tendons were compared by using Student t test. Clinical symptom scores served as the standard of reference. US findings were compared to clinical symptom scores by using Spearman correlation.

RESULTS: At semiquantitative analysis of SWE color charts, symptomatic tendons were rated as "soft" in 80/140 (57.1%), as "intermediate" in 54/140 (38.6%), and as "rigid" in 6/140 (4.3%). Healthy tendons were rated as "soft" in 8/84 (10%), as "intermediate" in 31/84 (37%), and as "rigid" in 45/84 (53%). At quantitative analysis, symptomatic tendons exhibited significantly lower mean SWE values (60.3 kPa/4.48 m/s; range 15.3-201.4 kPa/2.26-14.18 m/s) than healthy tendons (185 kPa/7.85 m/s; range 56-265 kPa/4.32-9.23 m/s) (P = 0.0004). SWE values correlated closely with patients' clinical symptoms obtained by clinical scores (r = 0.81). Overall sensitivity of conventional US and PD in detecting tendinopathies could be enhanced from 67.1% (94/140) to 94.3% (132/140) when combined with SWE.

CONCLUSIONS: SWE is a simple way to estimate tissue stiffness and, by reduced tissue rigidity, to identify tendon pathology. SWE significantly increases the diagnostic accuracy of tendon sonography and may prove to be a sensitive tool to early detect or monitor tendinopathy.