Contrast-enhanced ultrasound in the evaluation of parotid gland lesions: an update of the literature

Abstract

High-resolution ultrasound is the first line examination for parotid gland diffuse disease and focal lesions, normally using grey-scale and colour-Doppler ultrasound. Unfortunately, grey-scale and colour-Doppler ultrasound features of benign and malignant salivary gland lesions may overlap, particularly with benign tumors, where pleomorphic adenomas are often indistinguishable from malignant lesions. With atypical lesions, contrast-enhanced magnetic resonance imaging is usually the second level imaging modality requested. The introduction of ultrasound contrast agents has opened further possible perspectives to improve the interpretation of parotid diseases, particularly the differentiation between benign and malignant lesions. We present a review of the current literature on contrast-enhanced ultrasound for the assessment of parotid gland lesions, considering all characteristics of the technique, evidence of usefulness, future perspectives and limitations.

The EFSUMB Guidelines and Recommendations for the Clinical Practice of Contrast-Enhanced Ultrasound (CEUS) in Non-Hepatic Applications: Update 2017 (Long Version)

“…CEUS investigations were initially performed with high MI US using color Doppler [394] and later with low MI techniques [397,398]. The role of CEUS assessment of parotid gland lesions is limited by a paucity of studies, and relies on expert opinion [399,400].…”

Ultrasonography techniques in the preoperative diagnosis of parotid gland tumors – an updated review of the literature

“…Current US techniques can contribute to the differential diagnosis of parotid lesions. In 80-90% of cases tumors are localized in the superficial lobe [6][7][8]. Usually US is the initial method of choice for parotid tumors diagnosis, due to a large number of advantages (low-cost, accessible, non-invasive and non-irradiating technique).…”

“…US can make the differential diagnosis between benign and malignant tumors, can locate the intra-or extra-glandular lesions and is very helpful for the guidance of fine needle aspiration biopsy (FNAB). The technique presents a series of limitations such as: dependence of the operator, lack of standardized sections, low specificity in assessment of parotid tumors histological type, difficulty in evaluating tumors located in the deep parotid lobe or posterior to bone structures [1,5,[7][8][9][10][11][12][13][14].…”

“…A Warthin tumor (WT) usually has well-defined margins, internal cystic changes, hyperechoic internal septation, a more inhomogeneous structure and acoustic enhancement. Small, low-grade malignant tumors may appear well defined, homogeneous and hypoechoic, while large, high-grade malignant tumors present irregular, poorly defined margins, heterogeneous echotexture; extra-glandular spread and pathologic cervical adenopathy can be identified (fig 1, fig 2) [4,8,16,17].…”

“…On Doppler US, WTs and malignancies have a rich capsular and/or internal vascularization. PMA shows reduced vascularization [4,8,16,17].…”