Correlation between intravoxel incoherent motion MR parameters and MR nodular grade of parotid glands in patients with Sjogren's syndrome: A pilot study

Purpose: To explore the correlation between intravoxel incoherent motion (IVIM) magnetic resonance (MR) parameters and MR nodular grade of parotid glands in patients with Sjogren's syndrome (SS). Materials and methods: A total of 31 consecutive patients with SS and 28 gender- and age -matched healthy volunteers underwent bilateral parotid 3.0T MR examination including the IVIM sequence (9 b values, 0-800 s/mm(2)). The apparent diffusion coefficient (ADC), diffusion coefficient D, pseudo -diffusion coefficient D*, and perfusion fractionf of bilateral parotid glands were obtained, and the nodular grade of each parotid gland was evaluated according to the MR morphological appearance. Results: Sixty-two parotid glands in 31 patients with SS consisted of 32, 14, 8, and 8 parotid glands at MR nodular grades 0, 1, 2, and 3, respectively. In parotid glands of grade 0, 1, 2, 3 and healthy volunteers, the ADC values were (1.13 +/- 0.25, 1.11 +/- 0.17, 1.05 +/- 0.24, 0.89 +/- 0.04 and 1.00 +/- 0.21) x 10(-3) mm(2)/s, D values were (0.92 +/- 0.13, 0.90 +/- 0.19, 0.90 +/- 0.03, 0.67 +/- 0.03, 0.81 +/- 0.03) x 10(-3) mm(2)/s, f values were 0.20 +/- 0.04, 0.18 +/- 0.02, 0.15 +/- 0.01, 0.11 +/- 0.01, 0.15 +/- 0.06, and D*values were (53.89 +/- 28.26, 41.78 +/- 16.35, 51.24 +/- 18.69, 31.83 +/- 18.03, 36.83 +/- 16.14) x 10(-3) mm(2)/s respectively. The ADC, D, f, and D* values of parotid glands in patients with SS at grade 0 were significantly higher than those in healthy volunteers (all P < 0.05). Significant differences were observed in the D and f values of parotid glands in patients with SS among different grades (P = 0.003, < 0.001, respectively). The IVIM parameters (D, f) of parotid glands at early (grades 0-1) and advanced (grades 2-3) stages in patients with SS were significantly higher and lower, respectively, than those in healthy volunteers (all P < 0.05). The D and f values inversely correlated with MR nodular grades significantly (r = - 0.297, P = 0.019; r = - 0.653, P < 0.001, respectively) Conclusion: The parotid glands with different MR nodular grades in patients with SS showed different IVIM parameters, reflecting different pathophysiological characteristics of parotid glands at different stages. (C) 2016 Elsevier Ireland Ltd. All rights reserved.