From the Guidelines
Ultrasound (US) is the recommended initial imaging modality for parotid gland evaluation, as it allows for the detection and localization of major salivary gland tumors, as well as regional nodal staging, and is particularly effective for assessing masses in the superficial lobe of the parotid gland 1. The use of US as a first-line examination is supported by its ability to provide information on tissue characterization, anatomic delineation, and intralesional vascular pattern via Doppler technique. Additionally, US can serve as guidance for fine-needle aspiration and may be used to establish nodal involvement.
Some key benefits of using US for parotid gland evaluation include:
- High-resolution imaging of accessible salivary masses
- Effective and safe modality for initial assessment
- Ability to provide information on tissue characterization and anatomic delineation
- Can serve as guidance for fine-needle aspiration
However, it is important to note that US may have limitations, such as:
- Insufficient detection and characterization of masses located in the deep lobe of the parotid gland
- Inability to assess deep compartment extension, perineural tumor spread, bone invasion, and oropharyngeal/retropharyngeal nodal involvement
Other imaging modalities, such as CT and MRI, may be considered as secondary options or for further evaluation, as they offer additional benefits, such as:
- CT: provides information on bone invasion and can be used for staging
- MRI: offers excellent soft tissue contrast and can detect perineural spread and evaluate involvement of adjacent structures
However, according to the most recent and highest quality study 1, US is the preferred initial imaging modality for parotid gland evaluation, due to its effectiveness, safety, and ability to provide valuable information for diagnosis and management.
From the Research
Parotid Imaging Modalities
The recommended initial imaging modality for parotid evaluation is ultrasound, as it provides high-resolution images, is non-invasive, and does not expose patients to ionizing radiation 2, 3, 4, 5.
Advantages of Ultrasound
- Ultrasound is an excellent method for evaluating patients with parotid swelling, with a sensitivity of nearly 100% in detecting intraparotid tumors 3.
- It can provide clinically useful information by precisely outlining tumor borders or detecting multiple or bilateral lesions 3.
- Ultrasound is also useful for guiding fine-needle aspiration cytology, allowing for safe and accurate tissue sampling 2, 5.
Limitations of Ultrasound
- Ultrasound has limited visualization of the deep lobe of the parotid gland, which is obscured by the mandible 5.
- It may not be suitable for evaluating lesions in the sublingual gland or minor salivary glands, where MRI or CT is preferred 5.
Additional Imaging Modalities
- MRI or CT may be necessary for further evaluation if deep tissue extension is suspected or malignancy is confirmed on cytology 2, 5.
- These modalities can provide additional information on tumor extent, local invasion, and perineural spread 5.
- Sialography may be used to delineate the salivary ductal system, but it has a limited role in assessing tumor extent 5.