What is the best imaging modality, ultrasound versus computed tomography (CT), for a mobile, non-tender, rubbery mass located on the posterior neck, near the skull base, that has increased in size over the past year?

From the Guidelines

Computed Tomography (CT) is the preferred initial imaging modality for a mobile, non-tender, rubbery mass located on the posterior neck, near the skull base, that has increased in size over the past year.

Key Points

• CT has superior spatial resolution and is beneficial in evaluating the extent of deep neck inflammation and identifying a dental source of infection 1.
• CT is more readily available, costs less, and is generally more easily tolerated by patients compared to MRI, with a shorter scanning time and larger scanner bore 1.
• CT can help identify fat-containing lesions in the neck using Hounsfield units and is useful in guiding the search for an unknown primary malignancy 1.
• The American College of Radiology recommends CT neck with IV contrast or MRI neck without and with IV contrast as equivalent alternatives for the initial imaging of nonpulsatile neck masses 1.
• CT is preferred over MRI in this case, as the mass is located near the skull base and CT is better suited for evaluating bony structures and detecting potential malignancies 1.

From the Research

Imaging Modalities for Posterior Neck Mass

The choice between ultrasound and computed tomography (CT) for imaging a mobile, non-tender, rubbery mass located on the posterior neck, near the skull base, depends on various factors.

• Ultrasound:
  • Advantages: fast, safe, and cost-effective 2
  • Disadvantages: may require advanced clinical knowledge and experience to distinguish diseased tissues 2
  • Diagnostic accuracy: variable, with studies showing a range of sensitivities and specificities 3, 4, 5
• Computed Tomography (CT):
  • Advantages: clear anatomical structures, high diagnostic accuracy 3, 4
  • Disadvantages: radiation exposure, higher cost compared to ultrasound 6
  • Diagnostic accuracy: generally high, but may vary depending on the specific clinical scenario 3, 4, 5

Comparison of Ultrasound and CT

• Diagnostic Yield: similar diagnostic yields for ultrasound and CT have been reported in some studies 6
• Complication Rate: lower complication rates have been reported for ultrasound-guided biopsies compared to CT-guided biopsies 6
• Time to Diagnosis: ultrasound may offer a faster time to diagnosis compared to CT 6

Clinical Considerations

• Clinical Context: the choice of imaging modality may depend on the specific clinical context, including the patient's symptoms, medical history, and physical examination findings
• Imaging Guidelines: adherence to established imaging guidelines, such as those from the American College of Radiology, can help ensure appropriate use of imaging modalities 3, 4