Evaluation of Salivary Gland Function in Sjogren Syndrome with Diffusion-weighted MR Imaging and Dynamic MR Sialography

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This study was conducted to assess the utility of diffusion-weighted (DW) MR imaging with use of SPLICE technique and dynamic MR sialography after administration of tartaric acid, and to estimate the salivary gland function in patients with Sjogren syndrome (SS). Imaging parameters of DW MR imaging were: TR=5.9 msec, TE=65 msec, slice thickness=6 mm, gradient factor b= 205.38 and 1496.43 sec/mm^2. The ADC values of the parotid glands were calculated according to the signal intensities in the ROI on DW MR images. Dynamic MR sialography was obtained using a single-shot RARE sequence. Imaging parameters of dynamic MR sialography were: echo spacing=11. 5 msec, effective TE=1100 msec, ETL=240, slab thickness=30 mm. Immediately after intraoral administration of 2-ml of tartaric acid, sequential MR sialograms were obtained for 5 min. The study population was composed of 12 healthy subjects and 54 patients with SS. Labial gland biopsy and Saxon test were performed in all patients. The histopathologic grading was done by means of focus score. Calculated ADC values and morphologic pattern of dynamic MR sialography were compared with the results of labial gland biopsy and Saxon test. As to the ADC values between healthy subjects and patients with SS, no significant difference was observed. On the other hand, the ADC values in patients at early stage of the disease (focus score < 2) were statistically higher than those of healthy subjects. In all patients with SS, lack or reduced response to acid stimulation was seen on dynamic MR sialography. Even in patients with early disease condition in whom static MR sialography showed no significant morphologic abnormalities, dynamic MR sialography showed abnormal response to acid stimulation. Significant correlation was present between the results of dynamic MR sialography and Saxon test. We conclude that DW MR imaging and dynamic MR sialography are extremely useful for detecting the early disease condition of SS.