Quantitative analysis for modified Schall's classification by stimulation test with dynamic scintigraphy in Sjögren's syndrome

OBJECTIVES: To update Schall's classification for Sjogren's syndrome (SS) by the new quantitative stimulation test with dynamic salivary glands scintigraphy (qsDSGS) and to standardize quantitative salivary gland scintigraphy. METHODS: The histopathology, oral, ocular, serological examination and qsDSGS of 268 consecutive patients with suggestive SS were evaluated in this retrospective cohort study. The serological examination included 15 autoantibodies, antinuclear antibodies (ANA) and so on. The diagnostic thresholds of the functional parameters were set by the quantitative method, and the modified Schall's classification is well established and verified. RESULTS: Based on the quantitative analysis of qsDSGS, the peak uptake level (PUL) and stimulation excretion fraction (sEF) of each parotid gland were determined as the key imaging features, which had good diagnostic performance for SS. By the modified Schall's classification, all patients were classified into: Class 1 (normal; n = 44), Class 2 (mild to moderate involvement; n = 130), Class 3 (severe involvement; n = 56) and Class 4 (very severe involvement, non-function; n = 38). Using the threshold PUL