Sjögren's syndrome is a complex autoimmune disorder. The investigators hypothesize that striated ductal cells may function as non-professional antigen-presenting cells in Sjögren's syndrome. However, there are currently no established methods to assess the functional status of striated ductal cells or their relationship with clinical presentations. To address this knowledge gap, the investigators aim to investigate the potential of sialoscintigraphy, a non-invasive imaging technique, to evaluate the functional status of striated ductal cells. The sodium iodide symporter (NIS), predominantly expressed in striated ductal cells, facilitates the transport of technetium-99m, a radiotracer used in sialoscintigraphy. The investigators hypothesize that the expression level of NIS, as evaluated through sialoscintigraphy, may serve as an indicator of striated ductal cell function and potentially correlate with clinical manifestations in Sjögren's syndrome. However, the literature and our preliminary data lead us to hypothesize that age and the specific major salivary gland being evaluated may introduce confounding factors in the interpretation of sialoscintigraphy results. The investigators therefore proposed to 1) establish a nomogram of sialoscintigraphy stratified by age and specific salivary glands. The investigators will recruit healthy volunteers to receive sialoscintigraphy for the nomogram; 2) associate the expression level of NIS in the striated ductal cells from the major salivary glands with sialoscintigraphy, markers of antigen presentation, and disease manifestations of Sjögren's syndrome. The outcomes will help further applications of sialoscintigraphy in Sjögren's syndrome and formulate hypotheses to explore the pathological mechanisms underlying Sjögren's syndrome.