Salivary gland scintigraphy is a non invasive method widely accepted as an objective assessment of salivary gland function and a diagnostic criterion of primary Sjögren's Syndrome. In this study we evaluated the performance of qualitative and semi--qualitative salivary gland scintigraphy in primary Sjögren's Syndrome. Additionally we aimed to identify the scintigraphic patterns of salivary gland involvement in this condition.
Patients and methods: Observational study of fifty--six women with suspected primary Sjögren's Syndrome (pSS). Investigation included clinical history and observation, ophtalmologic examination, autoantibodies (SSA and SSB) determination, minor salivary gland biopsy and salivary gland scintigraphy interpreted according to Schall classification, visual quality of radioactivity uptake, morphology of time-activity curves and semi-quantitative parameters of uptake and excretion.
Results: Twenty patients fulfilled diagnostic criteria for pSS. Submandibular glands showed more pronounced functional impairment. In pSS patients, all scintigraphic parameters were significantly lower on these glands: a) qualitative evaluation ' visual quality of uptake (p=0,003), morphology of time-activity curves (p=0,001) and Schall classification (p<0,001); b) semi-quantitative parameters ' maximum counts (p=0,005), maximum counts/second/MBq administered (p=0,01), index of maximum counts versus counts at first minute (p=0,002) and excretion index (p=0,006).
Conclusions: Despite being qualitative and observer-dependent, Schall classification is valuable for the diagnosis of primary Sjögren's Syndrome. Nevertheless, semi-quantitative evaluation of salivary gland scintigraphy reveals significant differences in pSS patients and may have incremental value for the interpretation of salivary gland scintigraphy results.