Sjögren's syndrome of the parotid gland: value of diffusion-weighted echo-planar MRI for diagnosis at an early stage based on MR sialography grading in comparison with healthy volunteers.

PURPOSE: To investigate the value of diffusion-weighted echo-planar imaging (DW-EPI) for quantifying functional changes of the parotid gland in Sjogren’s disease and to evaluate whether ADC mapping allows for early diagnosis based on MR sialography grading. MATERIALS AND METHODS: Using a DW-EPI sequence at 1.5T (b-factors: 0, 500 and 1000 sec/mm 2 ), the parotid glands of 52 healthy volunteers and 13 patients with histologically verified affection of Sjogren’s disease were examined. All scans were performed prior to and following gustatory stimulation with 5 ml of lemon juice. ADC maps were evaluated by placing an inordinate region-of-interest (ROI) enclosing the entire parotid gland. Sjogren’s disease was graded based on MR sialography findings using a 4-point grading-scale. Statistics included student t-test and kappa-analysis. RESULTS: In healthy volunteers mean ADCs of 1.14 × 10 -3 mm 2 /sec before and 1.2 × 10 -3 mm 2 /sec after stimulation were observed. Higher ADCs were determined for early-stage Sjogren’s disease, averaging 1.22 × 10 -3 mm 2 /sec before and 1.29 × 10 -3 mm 2 /sec after stimulation. Advanced disease revealed significantly lower ADCs (0.97 × 10 -3 mm 2 /sec (p = 0.002) before and 1.01 × 10 -3 mm 2 /sec (p < 0.001) after stimulation). CONCLUSION: DW-EPI seems to display functional changes of the parotid gland affected by Sjogren’s disease. Combined with MR sialography, it might be a useful tool for discriminating healthy from affected glands and seems to allow differentiation between the early and advanced disease.