MR imaging of salivary glands.

In conclusion, if a parotid gland mass is bilateral, it is more likely to be Warthin's tumor, especially if it does not enhance. Less likely, it could be lymphoepithelial cyst or necrotic lymph node. A unilateral, non-enhancing mass with a high T2 signal is more likely to be a Warthin's tumor and less likely a necrotic lymph node or first branchial cleft cyst. If the mass is unilateral, shows postcontrast enhancement, has a high T2 signal, and does not invade surrounding tissue planes, it is more likely to be a pleomorphic adenoma. An intermediate to low T2 signal mass-with or without invasion of surrounding tissue planes--is more likely to be a malignant mass such as adenocystic or mucoepidermoid carcinoma. Biopsy is superior and the gold standard for diagnosis and cannot be replaced by MR imaging, however.