ROLE OF Gray Scale and Doppler Ultrasound in Diagnosis of Parotid and Submandibular Gland Diseases

* Salivary glands are affected by variety of disease processes which include infective, inflammatory, systemic, obstructive and neoplastic conditions . Clinical examination alone will not provide the correct diagnosis of salivary gland pathologies. Thus, radiological evaluation is essential in correct diagnosis .

USG plays a significant and crucial role in the diagnosis and management of salivary gland lesions. Results of the USG examination alone may suggest the final diagnosis or provide important differential diagnostic data . USG can differentiate intraglandular from extraglandular lesions in 98% of cases. It can differentiate salivary gland lesions as focal or diffuse. Characterisation of focal lesions into benign and malignant can be done by evaluation of edges. With high resolution transducers USG is better than CT or MRI in detection of unsharp borders .

Color Doppler findings are helpful in characterising the pathologies. It is helpful in diagnosing pleomorphic adenoma. Doppler findings of intralesional vascularity, type and grade of vascularity, PSV, RI and PI are useful in differentiating benign from malignant tumours . Pathological diagnosis can be established by Fine Needle Aspiration Cytology (FNAC). FNAC is preferably done under USG guidance. This helps in further enhancing ability of USG to differentiate between benign and malignant lesions .

Other radiological investigations for evaluation of salivary gland pathologies are plain radiography, sialography, CT, MRI and PET-CT .

Sometimes it is not possible to visualize lesions completely on USG because of their location, extension into the deep lobe of the parotid gland or behind the acoustic shadow of the mandible In these situations, further imaging with CT or MRI is necessary.