Ultra-High Frequency Ultrasonography in Sjögren's Syndrome

Overview

Patients diagnosed with a diagnosis of Sjogren's syndrome performed according to the ACR/EULAR criteria will be included in the study. Sjogren's syndrome diagnosis will be performed following a complete diagnostic work-up involving rheumatologic assessment, glandular functional tests, and blood testing for anti-Ro(SSA) antibodies. Conventional ultrasonography of major salivary glands and ultra-high frequency ultrasonography (70 MHz) of minor salivary glands will be performed, and the scans assessed using the Outcome Measures in Rheumatology (OMERACT) scoring system (Score 0 normal glandular tissue, Score 1 mild glandular alteration, fine echogenicity or diffuse hypo-echogenicity, Score 2 moderate glandular alteration and focal hypoechoic areas with partial conservation of normal parenchyma, Score 3 diffuse presence of hypoechoic areas in the absence of normal glandular parenchyma with glandular fibrosis. Focus Score will be assessed following biopsy of minor salivary glands.

Primary Sjögren's syndrome is a complex autoimmune disease involving the exocrine salivary and lachrymal glands, with a progressive functional impairment caused by lymphocytic infiltration in the glandular tissue. The diagnosis is currently performed according to the criteria established in 2016 by the American College of Rheumatologists/European League Against Rheumatism (ACR/EULAR) and relies on 5 items, namely i) histologic Focus Score (FS) ≥1, ii) positivity to Anti-SSA (Ro) antibodies, iii) Ocular staining score ≥ 5 (or van Bijsterfeld score ≥ 4) on at least one eye, iv) Schirmer test ≤ 5 mm/5min on at least one eye and v) Unstimulated Salivary Flow Rate (USFR) ≤ 0.1 ml/min. Focus Score and positivity to antibodies are items with a weight of 3 points each, while the other items are assigned score 1. Diagnosis is performed with a total score ≥ 4 when summing the weights. While the improvement in the sensitivity of ACR/EULAR classification criteria by 5-10% has been previously reported for ultrasonography of major salivary glands, at present no evidence is available for minor salivary glands. Minor salivary glands ultrasonography with the use of ultra-high frequencies up to 70 MHz has been recently introduced in the diagnostic work-up of Sjögren's syndrome, and involves the assessment of glandular ultrasonographic structural alterations through the application of the Outcome Measures in Rheumatology (OMERACT) scoring system, which is routinely used for major salivary glands. The present study therefore aims to assess the correlation between minor salivary glands ultrasonography and ACR/EULAR items, in order to evaluate whether this technique may integrate the current evaluation of Sjögren's syndrome patients.