Evaluation of diagnostic parameters from parotid and submandibular dynamic salivary glands scintigraphy and unstimulated sialometry in Sjögren's syndrome

Abstract

Our aim was to validate eight scintigraphic salivary gland (SG) parameters, as diagnostic parameters in patients with Sjörgen's syndrome (SS). We used the standardized stimulated dynamic salivary gland scintigraphy (DSGS) protocol and correlated this with the unstimulated whole sialometry (UWS) functions. The DSGS and UWS tests meeting the European and the USA diagnostic classification criteria for SS were applied in twenty patients and in ten normal controls. The DSGS tests were performed 60min after the intravenous (i.v.) injection of 370MBq of technetium-99m-pertechnetate (99mTcO-4) and after per os stimulation with a 0.5g tablet of ascorbic acid administered 40min after the injection. Using time-activity curves, eight different parameters were calculated for each parotid gland (PG) and each submandibular salivary gland (SMG): a) time at maximum counts (Tmax), b) time at minimum counts (Tmin), c) maximum accumulation (MA), d) accumulation velocity (AV), e) maximum secretion (MS), f) maximum stimulated secretion (MSS), g) stimulated secretion velocity (SSV), and h) uptake ratio (UR). Values of UWS below 2.5mL/15min were considered abnormal. All these parameters, as for the PG, showed significant abnormality in SS patients (P<0.001), especially of the secretion function. All SMG parameters also showed a significant abnormality (P<0.001), but especially of the accumulation function. There was a greater impairment of the above parameters in SMG than in PG in the SS patients. Sensitivity of the standardized DSGS was 100%, specificity 80%, negative prognostic value 100%, and positive prognostic value 91%. Sensitivity of UWS was 75%. In conclusion, this paper suggested that the best diagnostic parameters for the SS patients were those of: a) the maximum secretion, b) the maximum stimulated secretion for both the parotid and the submandibular glands, c) maximum accumulation and d) accumulation velocity of submandibular glands. The times at maximum and at minimum counts were non diagnostic.