The Validity of Salivary Gland Scintigraphy in Sjögren’s Syndrome Diagnosis: Comparison of Visual and Excretion Fraction Analysis

Abstract Introduction. The diagnostic value of salivary gland scintigraphy (SGS) in Sjögren’s syndrome (SS) is not completely known. Whether qualitative or quantitative methods of SGS interpretation are the most appropriate remains a matter of debate. We sought to determine whether the diagnostic discrimination of quantitative excretion fraction is higher compared to SGS qualitative visual analysis in a cohort of subjects with suspected SS. Materials and methods. Cross-sectional study that encompassed 204 subjects who underwent SGS for potential SS diagnosis. Based on clinical judgement, three groups were established: SS, non-SS autoimmune diseases (AID non-SS) and neither SS nor other AID (non-AID). In addition, American-European Consensus Group -AECG- and American College of Rheumatology -ACR- criteria were applied. Qualitative diagnosis through visual analysis -normal vs. abnormal and Schall’s classification grade- and semiquantitative and quantitative excretion fraction (EF%) scores were established following SGS assessment. The diagnostic discrimination of the different SGS scores for the various SS diagnostic modalities (clinical judgement and AECG and ACR criteria) was compared through their areas under the curve (AUC). Results. Most SGS parameters were significantly associated with SS-related clinical and laboratory features. Schall’s grade ≥ III was significantly more frequent in SS than in non-SS patients. In general, EF%-derived parameters did not show significant differences between groups. AUC of Schall’s classification reached statistical significance in its diagnostic discrimination for SS clinical judgement (AUC 0.704 [95%CI 0.597–0.811], p = 0.000) and AECG criteria (AUC 0.764 [95%CI 0.641–0.886], p = 0.000). Similarly the EF% submandibular mean (AUC 0.737 [95%CI 0.546–0.931] p = 0.032) was significantly associated with SS diagnosis through ACR criteria. However, AUC comparisons between qualitative and quantitative methods did not yield significant values. Conclusion. SS diagnostic discrimination of EF% is not superior to that obtained by qualitative visual analysis.