REAL-TIME strain elastography: Applications in musculoskeletal system

Strain or compression sonoelastography (CE) provides a colour-coded elastogram representing tissue elasticity by measuring tissue deformability after repeated probe compression. Elastographic ultrasound (EUS) is a valuable tool for screening diagnosis and follow-up of inflammatory, degenerative, benign and malignant neoplastic pathologies of skin, subcutaneous tissue, muscles, tendons, ligaments, fascia and nerves; help in targeted biopsy; monitor healing tendons after surgery or nerve stiffness changes during physiotherapy.

To assess stiffness of normal tendons, muscles and nerve. To diagnose cellulitis, fasciitis, abscess, tendinopathy, myositis, muscle/tendon rupture/contusion and differentiate between benign and malignant soft tissue tumours. To derive elastic score (ES) and strain ratio (SR) in cases and controls. To correlate B-mode findings with CE.

A prospective study on 50 healthy subjects between 25 and 30 years and 50 cases of diffuse and focal musculoskeletal pathologies was done using B-mode and CE over 2 years. Statistical analysis of distribution, mean, associations, sensitivity, specificity, area under Receiver Operating Characteristic curve (AUROC) for B-mode, ES, SR combined B-mode/CE and their comparison was done.

Significant association was noted between SR in muscles and tendons with sex. Significant correlation was noted between ES/SR with B-mode. CE and B-mode had 100% and 52.4% sensitivity respectively for diagnosing diffuse pathologies. For differentiating benign and malignant masses sensitivity, specificity, and diagnostic accuracy of B-mode was 71.43%, 86.36% and 82.76%; of SR was 71.43%, 90.91% and 86.21%; of Combined B-mode with CE was 100%, 90.91% and 93.1% respectively. Elastographic pattern had highest diagnostic accuracy and largest AUROC.

CE as a screening test had higher diagnostic accuracy, supporting need for standardizing it for clinical use in MSK. EUS being a widely available, fast and affordable modality, can aid follow up of chronic MSK pathologies, response to medication, physiotherapy and surgery and mitigate the need for MRI.