Objective: To validate ultrasonographic criteria for examination of the major salivary glands in the diagnosis of primary Sjögren's syndrome (SS).
Method: A total of 209 consecutive patients with rheumatic diseases were selected according to the American-European Consensus Group (AECG) classification criteria for SS. One hundred and fifteen patients had primary SS, 44 had secondary SS, and 50 had sicca symptoms, and 36 subjects served as asymptomatic controls. This cohort was analysed for size, echogenicity, parenchymal inhomogeneity, focal changes, and posterior borders of the major salivary glands by ultrasonography (US). A novel US score for parenchymal inhomogeneity (0-12) was assigned and its diagnostic accuracy evaluated.
Results: Ultrasonographic abnormalities of salivary glands were detected in 107/115 (93.0%) patients with primary SS, in 12/44 (27.3%) with secondary SS, in 25/50 (50.0%) with sicca symptoms, and in 4/36 (11.1%) asymptomatic controls. Area under the receiver operating characteristic curve (AUC-ROC) for US inhomogeneity score was highly significant [0.96 +/- 0.01; 95% confidence interval (CI) 0.94-0.99, p < 0.000] for primary SS, with a sensitivity to specificity ratio of 91/83 for parotid and 93/90 for submandibular glands. Setting the cut-off US inhomogeneity score at 6 resulted in the best ratio of specificity (90.0%) to sensitivity (95.1%), with a positive predictive value of 72% and a negative predictive value of 96%. A US inhomogeneity score >or= 6 was closely correlated with positive biopsy (p < 0.000) and scintigraphy findings (p < 0.000).
Conclusions: We demonstrate the high diagnostic value of a novel US score for parenchymal inhomogeneity (0-12) that could serve as a useful single US criterion in the evaluation of salivary gland involvement in primary SS.