Applicability of shear wave elastography for lacrimal gland evaluation in primary Sjogren syndrome

INTRODUCTION Primary Sjogren syndrome (pSS) is a systemic autoimmune disease that mainly affects the salivary and lacrimal glands, leading to their progressive destruction. OBJECTIVES The primary aim of this study was to verify whether shear wave elastography (SWE) of the lacrimal glands can be used to differentiate patients with pSS from healthy controls. The secondary aim was to assess whether there are any associations between SWE values, results of other ocular tests included in pSS diagnosis (the Schirmer test, ocular staining score [OSS]), and subjective symptoms of eye dryness. PATIENTS AND METHODS The study included 45 patients with pSS (41 women, 4 men) and 108 healthy controls (104 women, 4 men). All pSS patients met the 2016 American College of Rheumatology / European League Against Rheumatism pSS classification criteria. The participants underwent bilateral SWE of the lacrimal glands with the results expressed in kilopascals (kPa). The Schirmer test was performed in all patients, and OSS was calculated only in the pSS group. RESULTS The patients with pSS had significantly higher SWE values for the lacrimal glands than the controls. No significant differences in SWE results were observed between the groups of pSS patients with or without eye dryness confirmed by the Schirmer test and OSS, or the pSS patients with or without subjective symptoms of eye dryness. The optimal cutoff point for the diagnosis of pSS for the mean result of left and right lacrimal gland elastography was 7.2 kPa (sensitivity, 88.9%; specificity, 88%). Lacrimal gland SWE values may be a good classifier for the diagnosis of pSS, with an area under the receiver operating characteristic curve of 89.8 (95% CI, 81.5-98.1). CONCLUSIONS SWE of the lacrimal glands is a noninvasive, quantitative method that seems to be a reliable additional examination tool to support the diagnosis of pSS. Its role among the functional tests has not yet been well defined. To confirm the usefulness of SWE for pSS diagnosis, a standardized and widely accepted study protocol should be defined first.