Parotid and parapharyngeal tumours: tissue characterization with dynamic magnetic resonance imaging.

Prospective studies were performed to characterize parotid and parapharyngeal tumours using dynamic magnetic resonance (MR) imaging. Bolus injection of gadopentetate dimeglumine and a short SE sequence were used to evaluate 23 masses including seven pleomorphic adenomas, seven Warthin's tumours and nine malignant tumours. Contrast enhancement profiles helped to distinguish the different types of parotid and parapharyngeal tumours. Gradual increase in intensity during the first 260 s after the injection was characteristically found in pleomorphic adenomas and adenoid cystic carcinomas. Conversely, all Warthin's tumours showed a rapid increase during the first 20 s followed by a decrease in signal intensity. The other malignant tumours showed a rapid increase during the first 20 s followed by gradual decrease or increase at a slow rate. We suggests that the gradual increase in signal intensity of pleomorphic adenoma and adenoid cystic carcinoma may be due to their hypovascularity and an abundance of interstitial regions rich in connective tissue-type mucin. Dynamic MRI shows promise in tissue characterization of parotid and parapharyngeal tumours.