Introduction:
The salivary glands are exocrine glands which have two functions,firstly is the production of saliva which helps the passage of food through the oesophagus to the stomach, secondly the salivary enzymes which are responsible for the breakdown of nutrients so it is responsible for the first step of digestion.
The salivary glands are divided into major and minor groups.The major glans are three pairs which are the parotid, submandibular and sublingual while the minor glands are numerous and scattered in the nasal and oral cavities, paranasal sinuses, soft palate, larynx and pharynx.
Diseases may affect salivary glands either as a separate disease or as a part of systemic disease.
These diseases may be benign non-neoplastic, benign neoplastic or
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Most malignant lesions of the parotid are mucoepidermoid carcinoma.
Cutaneous malignancies may lead to malignant lymphadenopathy in the parotid especially basal cell carcinoma and melanoma.
MRI can be used to image salivary gland masses but can not differentiate the histologic types as all tumors are hypotense to gland on T1WMR image and all of them enhance on postcontrast MR images, but it can differentiate between solid and cystic lesions. [5]
MRI is preferred over CT when there is neural and meningeal involvement. Imaging of malignancies shows invasion of the adjacent structures (nerves, bone, skull base, meninges and adjacent cervical spaces) and capsule rapture in pleomorphic adenoma all of them are better viewed by MRI.
Postgadolinium, fat-supporetd T1W images are preferred for determining the invasions.
Malignancies are also characterized by ill-defined margins in post contrast images. [5]
Pleomorphic adenoma is homogeneously hyperintense on T2W, while the presence of mass with low to intermediate intensity on T2W images is an indication of