The aim of this retrospective study was to evaluate the diagnostic value of semiquantitative parameters in salivary gland scintigraphy (SGS) in the diagnostic work-up of primary Sjögren's Syndrome (SS) using the American-European consensus criteria (AECC) as the gold standard.
99mTc-pertechnetate-SGS was performed in 110 patients with suspected primary SS. Uptake ratios (URs) and excretion fractions (EFs) for all parotid and submandibular salivary glands were calculated. Patients were divided into SS-positive, SS-negative, and SS-equivocal groups on the basis of the AECC criteria. SGS semiquantitative parameters were compared per group and cut-off values were defined.
Ninety-six (87%) women and 14 (13%) men with a mean age of 51 years (range: 18-77 years) were included. All patients underwent SGS, labial biopsy, Schirmer's test, and antibody tests (anti-SS-A and anti-SS-B). Twenty-four patients were SS positive, 56 patients were SS negative, and 30 patients were SS-equivocal.UR of the parotid glands did not differ between SS-positive and SS-negative groups [mean (range): 3.4 (1.4-6.9) and 3.9 (2.2-6.5), respectively], whereas UR of the submandibular glands were significantly lower in SS-positive patients [mean (range): 2.7 (1.1-5.6) and 3.5 (2.3-5.3), respectively]. EF in both parotid and submandibular glands was significantly lower in SS-positive patients compared with SS-negative patients: parotid 24% (range: -4 to 53%) and 36% (range: 15-58%), respectively; submandibular 16% (range: -5 to 46%) and 29% (range: 9-49%), respectively.On the basis of a cut-off value of 2.0 for UR and 20% for EF, the sensitivity, specificity, positive predictive value, and negative predictive value were 0.67, 0.86, 86, and 67%, respectively. Of 30 SS-equivocal patients, 15 had a positive SGS, whereas the other 15 were SGS negative. In both, there was no correlation with the AECC criteria IV (histopathology) and VI (antibodies). In these cases, the SGS result was decisive.
Quantitative SGS is a valuable tool in the diagnostic management of patients with suspected primary SS, especially in those in whom the nonscintigraphic AECC criteria are not conclusive. The straightforward quantitative analysis of SGS used in this study can be implemented in any nuclear medicine department.