Does a computed tomography (CT) scan of the head and neck for oral cancer require contrast?

From the Guidelines

A CT scan of the head and neck for oral cancer evaluation typically requires contrast to accurately assess the primary tumor site, regional nodal staging, and osseous involvement. The use of contrast-enhanced CT (CECT) is supported by recent evidence, including a 2023 study published in the Journal of the American College of Radiology, which highlights the importance of CECT in providing detailed anatomic delineation of the primary tumor site and aiding in correct T staging and regional nodal staging of the neck 1.

Key points to consider when using contrast in CT scans for oral cancer evaluation include:

• The standard approach involves intravenous iodinated contrast administered at a dose of approximately 1-2 mL/kg body weight immediately before scanning
• Contrast enhancement is essential for differentiating tumor tissue from surrounding structures, assessing tumor vascularity, and identifying lymph node involvement—critical factors in oral cancer staging
• However, contrast may be omitted in patients with severe renal impairment (GFR <30 mL/min), previous severe contrast reactions, or when evaluating only for bony invasion, in which case alternative imaging like MRI with non-iodinated contrast agents might be considered 1
• Patients should fast for 4-6 hours before the scan if contrast will be used, and should inform their provider about any allergies, kidney problems, or medications they take, particularly metformin, which may need to be temporarily discontinued

It's worth noting that while a 2017 clinical practice guideline published in Otolaryngology--head and neck surgery recommends ordering neck CT with contrast for patients with a neck mass deemed at increased risk for malignancy, the most recent and highest-quality evidence supports the use of contrast in CT scans for oral cancer evaluation 1. However, the 2023 study provides more specific and detailed information on the use of CECT in oral cancer staging, making it the preferred reference for guiding clinical practice 1.

From the Research

CT Scan for Oral Cancer

• The use of contrast in a computed tomography (CT) scan of the head and neck for oral cancer is not explicitly stated as a requirement in the provided studies 2, 3.
• However, a study comparing contrast-enhanced CT (CECT) and MRI for detecting neck metastasis of oral cancer found that CECT was able to identify a greater number of metastatic lymph nodes than MRI 4.
• The use of contrast agents, such as gadolinium-based contrast agents (GBCAs), has been associated with risks, including nephrogenic systemic fibrosis and deposition in the brain, bones, and other organs 5, 6.
• Research is underway to reduce the quantity of gadolinium injected and to develop new contrast agents with high relaxivity and stability, which may enable a reduction in the gadolinium dose administered while maintaining good image quality and diagnosis 6.

Imaging Modalities for Oral Cancer

• CT is often the first-line imaging tool used for oral cancer due to its rapid image acquisition and relatively low cost 2, 3.
• MRI is better suited for certain types of head and neck tumors, such as sinonasal, nasopharyngeal, and salivary gland tumors, due to its ability to provide better delineation of tumor extent 2.
• PET/CT is usually reserved for advanced disease to evaluate for distant metastatic disease and posttreatment residual and recurrent disease 2, 3.