Ultrasonography of the salivary glands.

Sonography and computed tomography play complementary roles in imaging mass lesions in the salivary glands and their surroundings. Ninety per cent of parotid tumors originate from the superficial lobe, and we consider sonography to be the method of choice for imaging these lesions. The sensitivity of high-resolution sonography in detecting intraparotid tumors approaches 100 per cent, and ultrasound is therefore an excellent method to evaluate patients with parotid swelling. It may provide clinically useful information by precisely outlining the tumor borders or by detecting multiple or bilateral lesions. We restrict our use of CT to tumors that appear to extend beyond the borders of the parotid gland with possible invasion of surrounding soft tissues or bone. CT is also the method of choice for differentiating lesions of the deep lobe from parapharyngeal tumors and for staging carcinomas. Although ultrasound supplemented with computed tomography should replace conventional sialography in the work-up of parotid neoplasms, sialography remains the method of choice for evaluating patients with chronic sialadenitis, autoimmune diseases, and sialolithiasis. The role of sonography in these conditions is limited to ruling out a parotid neoplasm, assessing the extent of abscess formation, or assisting in localizing calculi in selected patients.