From the Guidelines
A contrast-enhanced CT scan is recommended for evaluating the parotid gland. This is based on the most recent and highest quality study available, which suggests that CT neck with IV contrast is usually appropriate for the initial imaging of parotid region masses 1. The use of contrast enhancement allows for better visualization of the parotid gland's internal architecture, vascular structures, and any pathological processes such as tumors, inflammation, or stones.
Key Considerations
- A slice thickness of 1-3 mm is generally used to provide adequate detail, and both axial and coronal reconstructions should be obtained for comprehensive evaluation 1.
- CT scanning is particularly valuable for assessing calcifications, bone involvement, and deep lobe extension of parotid masses.
- It also helps in distinguishing between intra- and extra-parotid pathologies and evaluating adjacent structures.
- While MRI provides superior soft tissue contrast for parotid imaging, CT remains valuable due to its wider availability, lower cost, faster acquisition time, and better visualization of calcifications and bony structures.
Special Considerations
- For patients with contraindications to contrast agents (such as severe renal impairment or allergy), non-contrast CT may be performed but offers less diagnostic information 1.
- Regular follow-up is recommended following treatment of malignant salivary gland neoplasms, with CT scans being a valuable tool for surveillance and detecting recurrences 1.
From the Research
Types of CT Scans for Parotid Gland Evaluation
- Contrast-enhanced CT is regarded as the preoperative imaging modality of choice for parotid gland tumor evaluation 2
- High-resolution CT scanning with contrast can provide enough preoperative information to enable the surgeon to counsel the patient concerning possible risks and the extent of surgery that may be indicated 3
- The most helpful scanning delay for predicting histologic subtypes of parotid gland tumors is 50 seconds after the start of contrast injection 2
Comparison with Other Imaging Modalities
- Magnetic Resonance (MR) imaging appears to be superior to CT for evaluating parotid masses and for distinguishing neoplasms of the parotid gland from those originating within the parapharyngeal space 4
- MR imaging has better contrast resolution than CT, making it superior in distinguishing the parotid gland from surrounding structures 4
Considerations for CT Scan Interpretation
- The density of parotid and/or submandibular glands on contrast-enhanced CT scans can be increased after radiation therapy for tumors of the head and neck 5
- Volumetric changes of parotid glands during intensity-modulated radiotherapy (IMRT) in head and neck cancer patients should be taken into account, with a significant volume loss observed during the third week of treatment 6