Sialocintigraphy versus ultrasonography of the salivary glands in patients first diagnosed with Sjögren's syndrome

Sjogren’s syndrome (SjS) is an autoimmune disease characterized by distraction of particularly salivary and lacrimal glands. The aim of the present study was to compare salivary gland scintigraphy (SGS) and salivary gland ultrasonography (SUS) in identifying salivary gland function in patients first diagnosed with SjS. We recruited 20 such patients with SjS (5 male, 15 female, aged from 35 to 65 y, mean age 52, standard deviation: ±5 y. All patients were submitted to SUS and SGS longitudinal and transverse images. Before the scintiscan, patients fasted for 6 h. Technetium-99m pertechnetate (99mTc-PT) 110 MBq was injected intravenously (i.v.) and simultaneous multi-frames dynamic acquisition was performed for 30 min. In two patients who had discordant results between SUS and US, labial biopsy was performed. Dynamic acquisition curves for 30 sec for the parotid and the submandibular glands were generated. For each gland we have calculated: (a) the maximum uptake (MU): the ratio between the mean counts in the gland at 20 min and the background activity and (b) the outflow efficiency (OE): the ratio between the minimum counts after lemon juice stimulation at 30 min and the counts at 20 min. The results showed abnormal scintiscans with low MU and high OE in one or more of the glands, in 17/20 patients. These results were confirmed by SUS in 15 cases and in two cases labial biopsy confirmed the diagnosis made by SGS while SUS was negative. In the remaining 3/20 cases of SjS both tests, SUS and SGS, showed normal results. Discrepancies between SGS findings and labial biopsy as found in two of our cases, have been reported by others and may be due among other causes, to early lymphocytic infiltration in SjS. Normal findings of SGS have also been reported. In conclusion, in cases first diagnosed with SjS, the function of the parotid and the submandibular glands was better identified by the SGS as compared to SUS. Although SGS is a more complex and expensive examination, it should be preferred to SUS as more sensitive and indicating the stage of SjS.