Objectives: Salivary glands ultrasonography has recently been shown to be useful in the diagnosis of Primary Sjögren's Syndrome (pSS). Shear-wave elastography (SWE) is a promising tool for the quantitative assessment of tissues stiffness, but studies evaluating its role in pSS diagnosis are limited. This study aimed at investigating the diagnostic performance of SWE in pSS.
Materials and methods: Cross-sectional study including patients fulfilling the 2016 ACR/EULAR classification criteria for pSS and healthy subjects. The four major salivary glands were assessed using SGUS. B-mode scans were rated using the Hočevar score, and shear-wave velocity (SWV) values were obtained using SWE. Intraclass-correlation coefficient (ICC) estimates were used to assess reliability. Cut-off values for differentiating pSS patients from healthy subjects were calculated using Receiver-Operating Characteristics (ROC) curves.
Results: We included 50 pSS and 25 healthy subjects. Inter-rater reliability of SWE was moderate (ICC=0.64) and intra-rater reliability was moderate to good (ICC= 0.73 to 0.83). Total SWV (2.09 m/s (0.32); p < 0.001), parotid SWV (2.25 m/s (0.40)) and submandibular SWV (1.92 m/s (0.38)) were significantly higher in pSS patients. Total and parotid SWV presented good diagnostic performance for pSS diagnosis (AUROC= 0.80 and 0.81, respectively). The Hočevar score demonstrated excellent diagnostic performance (AUROC= 0.98) and combining it with total SWV did not result in statistically significant improvement (p=0.301).
Conclusions: SWE may contribute to the diagnosis of pSS. Large prospective studies including sicca and secondary SS patients, as well as the standardisation of SWE protocols, are warranted to assess the role of SWE in pSS management.