What is the role of contrast-enhanced (Computed Tomography) CT of the neck in cancer screening and diagnosis?

Role of Contrast-Enhanced CT of the Neck in Cancer Screening and Diagnosis

Contrast-enhanced CT of the neck is the primary imaging modality for diagnosing suspected head and neck malignancies in adults, but it has no role in cancer screening—it should only be ordered when clinical findings suggest increased malignancy risk. 1

Not a Screening Tool

Contrast-enhanced CT neck is not used for cancer screening in asymptomatic individuals. 1 It is a diagnostic tool reserved for patients with:

• Neck masses present >2 weeks without infectious etiology 2
• Persistent symptoms (chronic throat pain, hoarseness >2 weeks, non-healing oral ulcers, dysphagia, unexplained weight loss) 1
• High-risk features (tobacco/alcohol use, age >40, prior head/neck malignancy) 1, 2
• Palpable cervical lymphadenopathy requiring evaluation 3

Diagnostic Role: When and Why to Order

Primary Indications

Clinicians should order contrast-enhanced CT neck for any adult neck mass deemed at increased malignancy risk. 1 This represents a strong recommendation based on its ability to:

• Localize and characterize the primary tumor with detailed anatomic delineation for accurate T-staging 1
• Assess depth of invasion in oral cavity cancers (accurate for lesions >5mm) 1
• Detect osseous involvement with high sensitivity and specificity—CT performs equal to or better than MRI for bone destruction 1
• Evaluate cartilage invasion in laryngeal/hypopharyngeal cancers (though MRI has slightly higher sensitivity) 1
• Stage regional lymph nodes throughout all neck levels from skull base to thoracic inlet 1
• Screen for occult primary tumors in the upper aerodigestive tract when presenting with metastatic neck nodes 1

Specific Cancer Types

For oral cavity, oropharynx, hypopharynx, and larynx cancers: Contrast-enhanced CT neck is mandatory for initial staging, providing accurate tumor thickness measurements and nodal staging comparable to MRI. 1

For salivary gland malignancies: CT with IV contrast is strongly recommended when bone involvement is suspected (temporal bone, skull base, mandible, palate), as it provides superior osseous detail compared to MRI. 1

For sinonasal cancers: CT neck with contrast allows detection and localization while providing excellent delineation of skull base and sinonasal skeleton. 1

Technical Requirements

Protocol Specifications

• Coverage: Skull base (top of frontal sinuses) to aortic arch 1
• Contrast: IV iodinated contrast is imperative to distinguish tumor from normal soft tissue 1
• Reconstructions: Thin slices with multiplanar reformats using both soft tissue and bone algorithms 1
• Timing: Optimal tumor contrast occurs 50-75 seconds after contrast injection start 4

Special Techniques

The puffed-cheek technique (patient inflates cheeks with pursed lips during scanning) improves delineation of oral cavity tumors along gingiva and buccal mucosa by separating tumor from normal mucosa. 1

Advantages Over Other Modalities

CT is preferred as the primary imaging modality because it: 1

• Is more readily available than MRI
• Costs considerably less than MRI
• Has shorter scan time (<5 minutes vs >30 minutes for MRI)
• Better tolerated by claustrophobic patients
• Provides superior bone detail for surgical planning 1
• Acceptable radiation dose (3 mSv, equivalent to ~150 chest x-rays) in adults 1

Limitations and When to Add MRI

CT alone may be insufficient when: 1

• Perineural invasion or skull base involvement is suspected—MRI with gadolinium provides superior soft tissue contrast and perineural spread detection 1
• Nasopharyngeal primary is suspected—MRI has improved sensitivity for skull base abnormalities 1
• Dental artifact obscures tonsillar fossa/tongue base—MRI or specialist examination needed 1
• Cartilage invasion assessment in laryngeal cancers—MRI shows slightly higher sensitivity 1

Role of PET/CT

PET/CT is not sufficient for initial staging alone but is recommended as an adjunct for stage III-IV cancers to detect distant metastases and synchronous tumors. 1 It should be used in conjunction with contrast-enhanced CT or MRI, not as a replacement. 1

Common Pitfalls to Avoid

• Never order CT without contrast for suspected malignancy—it provides inadequate soft tissue characterization and cannot distinguish tumor from normal structures 1
• Do not use CT without and with contrast routinely—there is no literature supporting dual-phase imaging for head and neck cancer staging 1
• Avoid empiric antibiotics for neck masses without clear infectious etiology, as this delays cancer diagnosis 2
• Do not rely on imaging alone—histologic confirmation via FNA or biopsy is mandatory for any suspected malignancy 1, 2

Contraindications and Modifications

Contrast administration protocols may require modification in: 1

• Contrast allergy (consider premedication or alternative imaging)
• Renal insufficiency (assess creatinine clearance)
• Pregnancy (imaging recommendations altered; consider MRI without gadolinium)