Sonoelastography techniques in the evaluation and diagnosis of parotid neoplasms

Ultrasound is the first-line imaging investigation in the evaluation of parotid gland lesions; however, ultrasound alone cannot differentiate between benign and malignant lesions. An imaging technique with this capability would be of great value, as fine needle aspiration cytology (FNAC) is not always accurate and partial/total parotidectomy is associated with facial nerve palsy and Frey's syndrome. Sonoelastography is a novel imaging technique that has been employed in the research setting in the evaluation of tissues including breast, thyroid, prostate and the salivary glands. More recently it has been used as a diagnostic adjunct in the sonographic evaluation of major salivary gland lesions. This review article outlines the current role of sonoelastography in the diagnostic imaging of parotid lesions, with particular reference to the findings of two research papers published in European Radiology. These papers employ slightly different techniques: the first utilises shear wave elastography whilst the second uses real-time sonoelastography. Sonoelastography may have potential as a diagnostic imaging adjunct to conventional ultrasound. However, it seems likely that FNAC/core biopsy will continue to be necessary. Further studies to evaluate the reproducibility of sonoelastographic results across a range of operators and systems are also needed. Key Points • Ultrasound is the initial and often definitive investigation for parotid lesions • Ultrasound-based strain elastography has been attempted but offered little additional information • New shear wave elastographic techniques did not confer much advantage either • However, analysis of elastographic patterns seems to provide advantages over ultrasound alone.