Combination of ultra-micro angiography and sound touch elastography for diagnosis of primary Sjögren's syndrome: a diagnostic test.

Background: Primary Sjogren's syndrome (PSS) is a prevalent systemic autoimmune disease. However, the current gold standard diagnostic method is invasive, increasing the difficulty of patient acceptance and then delaying treatment. Therefore, a non-invasive, convenient, and effective diagnostic method is required. Although salivary gland ultrasonography (SGUS) is a good choice, previous studies have not found suitable parameters to diagnose PSS. Salivary gland involvement in patients with PSS leads to changes in gland stiffness and vascularization, so we combined sound touch elastography (STE) and ultra-microangiography (UMA) to demonstrate the diagnostic effectiveness of ultrasonography in PSS. Methods: This prospective study included 27 patients with PSS and 20 healthy controls, with all participants forming a random series. Major salivary glands were examined with UMA and STE. Color pixel percentage (CPP), shear wave velocity (SWV), and Young's modulus values were investigated, and the combination of these parameters was evaluated by logistic regression analysis. Results: For Young's modulus and SWV in the elasticity index, combined evaluation of both parotid glands and submandibular glands yielded an area under the receiver operating characteristic (ROC) curve (AUC) and confidence interval (CI) of 0.819, 0.699-0.938 and 0.801, 0.677-0.925, respectively. The levels of CPP in the parotid glands were significantly elevated (P<0.003) among patients compared to those in the control group, whereas the CPP values in the submandibular glands were not statistically different (P>0.086). We evaluated the elasticity values of the total 4 glands and the CPP of parotid glands together by logistic regression modeling. The ROC curve yielded an AUC of 0.954 (95% CI: specificity 0.849-0.994) which showed the best accuracy, with 92.6% sensitivity and 85.0% specificity. Conclusions: The use of STE and UMA to examine the salivary glands may aid in the diagnosis of PSS, and their combination may be a promising method. This is good news for patients with PSS who are not suitable or unwilling to undergo labial gland biopsy.