Non-invasive biomechanical characterization of intervertebral discs by shear wave ultrasound elastography: a feasibility study

Objectives Although magnetic resonance is widely spread to assess qualitatively disc morphology, a simple method to determine reliably intervertebral disc status is still lacking. Shear wave elastography is a novel technique that allows quantitative evaluation of soft-tissues’ mechanical properties. The aim of this study was to assess preliminary the feasibility and reliability of mechanical characterization of cervical intervertebral discs by elastography and to provide first reference values for asymptomatic subjects. Methods Elastographic measurements were performed to determine shear wave speed (SWS) in C6-C7 or C7-T1 disc of 47 subjects; repeatability and inter-operator reproducibility were assessed. Results Global average shear wave speed (SWS) was 3.0 ± 0.4 m/s; measurement repeatability and inter-user reproducibility were 7 and 10 %, respectively. SWS was correlated with both subject’s age (p = 1.3 × 10−5) and body mass index (p = 0.008). Conclusions Shear wave elastography in intervertebral discs proved reliable and allowed stratification of subjects according to age and BMI. Applications could be relevant, for instance, in early detection of disc degeneration or in follow-up after trauma; these results open the way to larger cohort studies to define the place of this technique in routine intervertebral disc assessment. Key Points • A simple method to obtain objectively intervertebral disc status is still lacking • Shear wave elastography was applied in vivo to assess intervertebral discs • Elastography showed promising results in biomechanical disc evaluation • Elastography could be relevant in clinical routine for intervertebral disc assessmentThe authors are grateful to the ParisTech BiomecAM chair program on subject-specific musculoskeletal modelling for funding (with the support of ParisTech and Yves Cotrel Foundations, Société Générale, Proteor and Covea)