Sonoelastography of parotid gland tumours: initial experience and identification of characteristic patterns

Abstract

Objectives: The aim of this study was to investigate B-mode and elastographical ultrasound criteria capable of differentiating between benign and malignant parotid tumours and to define characteristic elastographical patterns for pleomorphic adenomas and Warthin's tumours.

Methods: Fifty-seven patients with parotid gland tumours were examined using a combination of B-mode and elastographic ultrasounds. The data acquired were analysed retrospectively by two experienced ultrasound operators to identify specific sonographical features of benign and malignant lesions. Additionally, elastographical patterns were defined and analysed for their specificity.

Results: A blurred margin proved to be the only significant criterion in B-mode ultrasound capable of differentiating between malignant and benign tumours. The garland sign was defined as an elastographical pattern found significantly more frequently in malignant tumours, improving sonographical prediction of the benign or malignant nature of a parotid lesion. A logistic regression model was developed that achieved a correct prediction in 87.7% of cases. A "dense core" sign was also specifically defined for pleomorphic adenomas and a "half-half" sign for Warthin's tumours.

Conclusions: Elastography is an innovative and powerful diagnostic tool that can improve the sonographical examination of parotid gland tumours by revealing easily recognised and characteristic patterns of tissue distribution.

Key points: • Elastography can help differentiate benign from malignant parotid tumours during parotid ultrasound. • The elastographical "garland sign" is more frequent in malignant than benign parotid tumours. • Pleomorphic adenomas show an elastographical "dense core sign". • Warthin's tumours show an elastographical "half-half sign". • Parotid cysts show an elastographical "bull's-eye sign".