Diffusion-weighted echoplanar MR imaging of the salivary glands

OBJECTIVE. We determined the apparent diffusion coefficients of normal and dysfunctional salivary glands. SUBJECTS AND METHODS. A diffusion-weighted single-shot spin-echo type of echoplanar MR imaging was performed on the parotid or submandibular glands, or both, in 36 healthy subjects, 20 patients with Sjogren's syndrome, and six patients with sialoadenitis. The apparent diffusion coefficient of the salivary gland was calculated using two b factors (b = 500 and 1,000 scc/mm(2)). RESULTS. The apparent diffusion coefficient was lower in the parotid glands (0.28 x 10(-3) mm(2)/sec) than that of the submandibular glands (0.37 x 10(-3) mm(2)/sec). The apparent diffusion coefficient was increased in sialoadenitis, whereas it decreased with abscess formation. The apparent diffusion coefficients of the parotid glands in patients with Sjogren's syndrome correlated with the salivary flow rates but not with the sialographic gradings of the glands. We also found a correlation of the decreases in apparent diffusion coefficients with the severity of gland damage as assessed on T1-weighted MR images. CONCLUSION. Diffusion-weighted echoplanar MR imaging may reveal diseased states of the salivary glands.