2.2 Aim(s) of the Research (50 words max): To investigate the diagnostic accuracy of Sonoelastography in the evaluation of major salivary gland lesions using histopathology as gold standard.

Salivary gland diseases are ranging from the minor inflammatory conditions to a group of benign and malignant neoplasms. Most of the salivary gland disorders manifest themselves as the enlargement of the gland which may be associated with pain or swelling. Physical examination together with laboratory analyses may not be sufficient to discriminate these diseases . Therefore, an accurate, non invasive diagnostic method is needed to discriminate these diseases (1).

Although ultrasound-guided fine-needle aspiration cytology (FNAC) is considered the gold standard for preoperative diagnosis (2), it is an invasive method requiring significant experience to avoid complications like injury of the facial nerve as it courses within the parotid gland. This explains the continuing desire for further non-invasive diagnostic options (3).

The current imaging modalities are ultrasonography, Computed Tomography (CT) and Magnetic Resonance Imaging (MRI). Despite being highly sensitive, they lack the accuracy in differentiating benign and malignant lesions because of considerable overlap between the imaging features of benign and malignant salivary gland lesions.

Sonoelastography is a new technique that depends on the elastic properties of soft tissues, with the idea of malignant lesions being stiffer than benign or normal tissue. It may have a dependable role in diagnosing different salivary gland diseases, the same way it has been used in different parts of the body, such as the breast, lymph nodes, and thyroid (4). To the best of our knowledge, there are few studies concerning the role of elastography in the field of salivary gland disease.

Inclusion Criteria

• All patients with clinically suspected lesions of parotid or submandibular glands .
• An equal number of healthy volunteers will be included during the same period as control group .

Exclusion Criteria:

• A mass with ulcerated or raw surface, involvement of the whole gland by the lesion or previous surgical treatment

Patients will be scanned in the supine position during free-breathing, with subtle neck hyperextension and tilt to the opposite side of the evaluation. The parotid and submandibular glands will be carefully examined in the transverse and longitudinal dimensions with an 8-12 MHz linear array transducer. Doppler assessment will then be done Subsequently, sonoelastography will be performed with the same depth and focus and gained settings as for grey scale imaging. First, strain elastography will be performed. The elastogram image of the detected lesion, will be evaluated using color coding . stiffness compared to normal parenchyma using a 4-grade system like the performed. Strain ratio values of all the lesiongrading presented by Dumitriu D et al. Second, shear wave elastography will be ps ,will also be calculated individually. All will be compared with histopathology results.