To assess the correlation between MR imaging (MRI) of parotid glands with X-ray sialography, histopathology of the labial salivary glands, and salivary secretion, in patients with secondary Sjögren's syndrome (SS) associated with rheumatoid arthritis (RA).
Non-contrast MRI of the parotid glands was performed in 13 secondary SS patients associated with RA who satisfied the revised Japanese diagnostic criteria for SS (1999), and the ACR/EULAR classification criteria for RA (2010). The MRI findings were classified according to the degree of high-intensity signal on T1-weighted images (T1WI) and short inversion time inversion recovery (STIR) images into five grades (0-4), using the modified Nagasaki University grading method. The results of MRI grading were compared with the Rubin and Holt staging of X-ray sialography (0-4), the Greenspan grading of labial salivary gland histopathology (0-4), and salivary secretion by the gum test (ml/10 min).
All 13 patients were females, with a mean age of 50.2 ± 11.3 years. According to the MRI grading, 3 patients were Grade 1, 5 were Grade 2, 5 were Grade 3, and none was Grade 0 or Grade 4. The mean stage by X-ray sialography was 1.7 ± 1.0, the mean grade by histopathology was 2.4 ± 1.2, and the mean volume of salivary secretion was 9.7 ± 3.9 ml. The MRI grading correlated significantly with the Rubin and Holt staging and Greenspan grading (P < 0.01 each, Spearman's rank correlation), and significantly and inversely with the results of the gum test (P < 0.05).
The results suggest that MRI of the parotid glands is a useful noninvasive tool for evaluating destruction and inflammation in the salivary glands.