Quantitative evaluation of salivary gland scintigraphy in Sjögren’s syndrome: comparison of diagnostic efficacy and relationship with pathological features of the salivary glands

The value of salivary gland scintigraphy (SGS) in the evaluation of Sjögren’s syndrome (SS) remains controversial. The aim of this study was to evaluate the diagnostic efficacy of quantitative SGS in patients with xerostomia and to assess the correlation between scintigraphic parameters and pathological features of salivary glands. Medical records of 165 patients with xerostomia who underwent [99mTc] pertechnetate SGS and labial biopsy were retrospectively reviewed. The maximum accumulation ratio (MAR), maximum secretion ratio (MSR), and time interval from stimulation to minimum count (Tmin) of the parotid glands were calculated to quantify the glandular activity. Furthermore, pre-stimulatory oral activity index (PRI) and post-stimulatory oral activity index (POI) were calculated to quantify the oral activity. All parameters except for Tmin were significantly lower in patients with SS than in those without SS. Among the five SGS parameters, PRI showed the highest areas under the curve value (0.9005; p < 0.001), and PRI > 32.75 was associated with a sensitivity of 78.5% and specificity of 86.4% for the diagnosis of SS. A decrease in MAR, MSR, PRI, and POI and an increase in Tmin correlate significantly with the histopathologic grade of labial gland biopsy and disease severity of SS. No significant differences in glandular parameters (MAR, MSR, and Tmin) were found between the non-SS and early-stage SS groups. Conventional scintigraphic parameters could be used as simple, reliable, and sensitive indicators for the early diagnosis of SS and determination of disease severity.