Shear Wave Elastography for Assessment of Muscular Abnormalities Related to Systemic Sclerosis.

Rationale and Objectives: To assess muscular abnormalities related to systemic sclerosis (SSc) using shear wave elastography and correlate results with those of clinical tests.
Materials and Methods: We evaluated 55 patients (mean age: 50.4 years; range: 18-88; 34 female) with SSc before treatment and choose muscle groups based on cutaneous involvement and functional impairment [forearms (9); thighs (41); thenar/hypothenar (5)]. We performed shear wave elastography in two orientations to access heterogeneity using virtual touch IQ and mean shear wave velocity values (SWV) and measured skin and fascia thickness. We compared SWVs to the modified Rodnan skin score (mRSS). Twenty-two healthy controls (mean age: 52.0; range: 19-88; 7 female) underwent the same protocol.
Results: SWV pattern analysis (homogeneous vs heterogeneous) detected SSc with sensitivity/specificity/negative predictive value/positive predictive value0.79/0.81/0.91/0.62 in transverse and 0.75/0.18/0.91/0.56 in longitudinal orientation. In patients we found poor correlation between SWVs and mRSS but a cutoff of mRSSE = 20 separated them significantly (p < 0.01). Skin and muscle fascia were significantly thicker in patients vs. controls (p < 0.001).
Conclusion: SSc involves more than increased skin and fascial thickness which is not fully represented by mRSS. Elasticity differs in muscles with and without SSc. The former shows higher SWV and increased heterogeneity in transversal planes of muscular fibers.
Competing Interests: Funding Jan Fritz received institutional research support from Siemens Healthcare USA, DePuy, Zimmer. Micorsoft, and BTG International; is a scientific advisor of Siemens Healthcare USA, Alexion Pharmaceuticals, and BTG International; received speaker's honorarium from Siemens Healthcare USA' and has shared patents with Siemens Healthcare and Johns Hopkins University. Horger Marius received institutional research support from Siemens Healthineers Germany; he is a scientific advisor of Siemens Healthineers Germany and received speaker's honorarium from Siemens Healthineers Germany.
(Copyright © 2020 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.)