POS0771 ULTRA HIGH-FREQUENCY ULTRASOUND (UHFUS) OF MINOR LABIAL SALIVARY GLANDS (MLSGS): DIAGNOSTIC ACCURACY IN ANTI-Ro/SSA POSITIVE AND ANTI-Ro/SSA NEGATIVE PATIENTS WITH PRIMARY SJÖGREN’S SYNDROME (pSS)

Abstract

BackgroundLast-generation Ultra High-frequency ultrasound (UHFUS) transducers are highly sensitive tools for the study of tiny superficial structures such as minor labial salivary glands (MLSGs). Compared to conventional ultrasound, UHFUS operates with higher frequencies allowing for outstanding image resolution, up to 30 µm.ObjectivesTo determine the diagnostic accuracy of MLSG UHFUS in primary Sjogren’s syndrome (pSS) and to assess its contribution in anti-Ro/SSA positive and anti-Ro/SSA negative patientsMethodsConsecutive patients undergoing a MLSG biopsy for clinically suspected pSS were included in this cross-sectional study from January 2018 to October 2021. MLSG UHFUS was performed by using a 70 MHz probe, evaluating parenchymal inhomogeneity (score 0-3, similar to major salivary glands four-grade OMERACT scoring system). Patients’ clinical, biological, and histological features were collected. Anti-Ro/SSA antibody specificity was determined by immunoblotting. Receiver operating characteristic (ROC) curves, optimal cut-off point, AUC (area under curve), sensitivity (SE), specificity (SP), positive (PPV) and negative predictive values (NPV) were identified.ResultsA total of 194 patients were enrolled. Out of them, 88 patients fulfilled the ACR/EULAR 2016 criteria for pSS and 74 were anti-Ro/SSA+ (69 pSS and 5 no-SS). The distribution of UHFUS grades was significantly different in patients with pSS than in no-SS subjects: grade 0: 0/88 (0) vs 17/106 (16%); grade 1: 28/88 (31.8%) vs 55/106 (51.9%); grade 2: 46/88 (52.3%) vs 31/106 (29.2%); grade 3: 14 (15.9%) vs 3(2.8%); p<0.0001. ROC curve analysis indicated that at the optimal cut-off value of 2, UHFUS identified pSS and no-SS patients with a SE=68.2%, a SP=67.9%, a PPV= 63.8%, and a NPV= 72% (AUC=0.722, 95%CI: 0.651-0.793) and can predict a FS≥1 at the MLSG biopsy with a SE =73%, a SP=63.4%, a PPV= 48.9% and a NPV = 83% (AUC= 0.732, 95% CI: 0.657-0.806). Subgroup analyses highlighted significant differences in UHFUS diagnostic accuracy between anti-Ro/SSA+ and anti-Ro/SSA- patients. Particularly, in the latter group UHFUS showed a higher diagnostic accuracy (AUC= 0.754, 95% CI: 0.641-0.867) with a NPV increased up to 93.3%; similarly, UHFUS showed a higher accuracy (AUC= 0.755, 95% CI: 0.650-0.860) in predicting a MLSG FS≥1 with a NPV raised up to 90.7%.ConclusionMLSG UHFUS score system presents a good SE and SP in distinguishing pSS from no-SS subjects. The diagnostic accuracy of MLSG UHFUS may be significantly enhanced when combined with anti-Ro/SSA antibodies status. If anti-SSA antibodies are negative and UHFUS grade is 0 or 1, the diagnosis of pSS is very improbable and MLSG biopsy could be avoided. Further studies are in progress to define the added value of UHFUS with respect to major salivary gland ultrasonography.Table 1.UHFUS diagnostic accuracy in pSS (A) and for predicting a MLSG FS≥1 in all the cases and in anti-Ro/SSA negative patients. OCP, optimal cut-off value.SESPPPVNPVAUC (95%CI)OCPpSS diagnosis (all pts)60/88 (68.2%)72/106 (67.9%)60/94 (63.8%)72/100 (72%)0.722 (0.651-0.793)2FS≥1 prediction (all pts)46/63 (73%)83/131 (63.4%)46/94 (48.9%)83/100 (83%)0.732 (0.657-0.806)2pSS diagnosis (SSA- pts)14/19 (73.7%)70/101 (63.9%)14/45 (31.1%)70/75 (93.3%)0.754 (0.641-0.867)2FS≥1 prediction (SSA- pts)17/24 (70.8%)68/96 (70.8%)17/45 (37.9%)68/75 (90.7%)0.755 (0.650-0.860)2Figure 1.ROC curves showing UHFUS diagnostic accuracy in pSS (A) and for predicting a MLSG FS≥1Disclosure of InterestsNone declared