Salivary gland ultrasonography as a diagnostic aid in Sjögren syndrome: a prospective investigational study

Abstract

Objectives Salivary glands ultrasonography (SGUS) is an emerging diagnostic aid for Sjogren syndrome (SS) with positive potentials because of its availability, noninvasiveness, and safety. The aim of this investigation was to assess and compare the ultrasonographic features of the parotid and submandibular salivary glands in patients with SS or dry mouth (DM) and in healthy controls and to evaluate the sensitivity and specificity of SGUS in the diagnosis of SS. Study Design This was a prospective observational 3-group comparison study. Patients diagnosed with SS (according to the 2016 American College of Rheumatology [ACR] and European League Against Rheumatism [EULAR] criteria, patients with DM (diagnosed on the basis of the subjective reporting of oral dryness and unstimulated salivary flow of Results Thirty-four female patients were enrolled in this investigation, of whom 76.5% were white. Twelve patients (35.3%) had definitive diagnosis of SS; 12 (35.3%) had DM; and 10 (29.4%) were healthy controls. The median age (interquartile range [IQR]) of patients in all 3 groups was 56.6 (± 14.2) years. Ninety-two percent of patients in both the SS and DM groups were on sialogogues, with the majority using cevimeline (83.3% and 41.6%, respectively). Overall, patients with SS showed significant SGUS features and had higher scores compared with patients with DM and controls. The median inhomogeneity score was significantly higher in the SS group compared with the DM and control groups in the right parotid gland (RPG), left submandibular gland (LSMG), and left parotid gland (LPG) (P = .000, .000, and .012, respectively), with no statistically significant differences detected between the SS and DM groups in the right submandibular gland (RSMG) only (P = .604). The median size of the hypoechogenic bands was statistically higher in all salivary glands (i.e., RSMG, RPG, LSMG, and LPG) in the SS group compared with the DM and healthy control groups (P =.000). When comparing the sizes of the glands, there were no statistically significant differences among the 3 groups in the median transvers dimension and height of the RPG (P = .846 and .137, respectively) and LPG (P = .382 and .538, respectively). Moreover, no statistically significant differences were observed in the median anteroposterior dimension and depth of the RSMG (P = .470 and .147, respectively) and LSMG (P = .495 and .695, respectively) among the 3 groups. Lack of visibility of the posterior borders of all glands was detected in the majority of patients in the SS group (RSMG = 66.6%; RPG = 83.3%; LSMG = 75%; LPG = 83.3%), whereas all patients in the DM and control groups had visible posterior borders (P = .000). The size of the sialolith, if present, did not show any statistically significant differences among the 3 groups in RSMG, RPG, LSMG, and LPG (P = .160, .136, .065, and .377, respectively). The SGUS, with a cutoff value of ≥ 2, showed sensitivity of 100% and specificity of 81.6% for detecting SS ultrasonographic features. Conclusions SGUS is a useful, noninvasive diagnostic modality with high sensitivity and specificity. Parenchymal inhomogeneity scores, sizes of the hypoechogenic bands, and visibility of the glands’ posterior borders may all have a good potential for detection of SS. We propose that the ACR and the EULAR take SGUS into consideration when reviewing/updating the diagnostic criteria for SS in the future.