Sonography of Salivary Glands

Abstract

Patients with salivary gland abnormalities present most commonly with painful or painless focal swelling, dryness of mouth or pain on eating certain type of food. The Sonography of Salivary glands needs to answer certain questions. Is there a focal mass? Is it benign or malignant? Is the lesion single or multiple? What is the location? Are there any Lymph nodes? US is accepted as the first imaging method for assessment of diseases of major salivary glands. Lesions in the deep lobe of parotid gland or behind the mandible are difficult to see. US needs to be complimented by MRI, and also when the tumors are large or appear to bulge into oral cavity or oropharynx. CT is considered better in assessment of inflammatory diseases of salivary glands. In acute inflammation, salivary glands are enlarged and are often hypoechoic. The glands may be inhomogeneous; may contain multiple small, oval, hypoechoic areas. In chronic inflammation, salivary glands are normal sized or smaller, hypoechoic, and inhomogeneous and usually do not have increased blood flow. Multiple small hypoechoic foci on a heterogeneous background. 60-90%Salivary calculi occur in the submandibular gland. Parotid calculi are relatively less commonUS and MR are the main modalities for detection of calculi and assessment of ducts. Bilateral glandular involvement. Parotid & Submandibular glands are commonly involved. Sometimes lacrimal glands are also involved. USG reveals heterogeneous echopattern, multiple round hypoechoic areas, reticulated pattern. Salivary gland neoplasms are not common. Most of them occur in Parotid glands (80-90%). Most of them are benign (70-80%). Neoplasm in submandibular gland is rare (10-20%) but almost 50% of them are malignant. The most common malignant neoplasms occurring in salivary glands are mucoepidermoid carcinoma and adenoid cystic carcinoma. Less than 30% of focal lesions in the parotid gland are malignant, whereas almost 50% of focal lesions in the submandibular gland are malignant. Ultrasound characteristics are Irregular shape, Irregular borders, Ill defined margins, and Hypoechoic inhomogeneous structure.