What is the best imaging modality, Computed Tomography (CT) scan or Magnetic Resonance Imaging (MRI), for evaluating a lump on the nose?

Imaging Modality for Evaluating a Lump on the Nose

CT maxillofacial is the recommended first-line imaging modality for evaluating a lump on the nose, with MRI reserved for cases requiring better soft tissue characterization or when intracranial extension is suspected. 1

Initial Imaging Approach

CT Maxillofacial (First-Line)

• Best depicts osseous changes and can distinguish between bony remodeling (typical of slow-growing or benign masses) and lytic destruction (seen with aggressive malignancies) 1
• Demonstrates lesion mineralization, including osseous matrix of osteomas, chondroid matrix of cartilaginous tumors, and ground glass density of fibro-osseous lesions 1
• Provides detailed depiction of sinonasal anatomy essential for surgical planning 1
• Can be used with surgical image-guidance systems when acquired with appropriate protocol 1

When to Consider MRI (Second-Line or Complementary)

• When better soft tissue characterization is needed 1
• When intracranial extension is suspected 1
• When perineural involvement needs to be evaluated 1
• To distinguish tumor from inflammatory changes (MRI shows better T2 contrast between tumor and inflammatory tissue) 1

Comparative Advantages

CT Advantages

• Superior visualization of bony anatomy and erosion 1
• Better detection of calcifications within masses 1
• More widely available and typically less expensive than MRI 2
• Shorter acquisition time (important for claustrophobic patients) 3

MRI Advantages

• Superior soft tissue contrast 1
• Better characterization of specific pathologies through signal characteristics 1
• Better detection of intracranial and perineural involvement 1
• No radiation exposure 2
• Can better detect osseous marrow invasion compared to CT 1

Clinical Decision Algorithm

1. Initial presentation of nasal lump:

   • Start with CT maxillofacial as the first-line imaging study 1
   • Consider contrast-enhanced CT if soft tissue involvement is suspected 1

2. Add MRI when:

   • CT shows concerning features suggesting malignancy 1
   • Soft tissue characterization is inadequate on CT 1
   • Intracranial or orbital extension is suspected 1
   • Perineural spread needs evaluation 1

3. Specific scenarios requiring both modalities:

   • Suspected malignancy (complementary information from both modalities improves staging) 1
   • Pre-surgical planning for complex cases 1
   • When initial imaging is inconclusive 2

Important Considerations

• Plain radiography is not recommended for evaluating sinonasal masses due to limited diagnostic value and high false-negative rates 1
• Cone beam CT is not useful for sinonasal mass evaluation due to limitations in assessing soft tissue structures 1
• If both CT and MRI are planned, the CT can be performed without IV contrast since its main purpose is to evaluate osseous involvement 1
• Most sinonasal neoplasms ultimately require histologic sampling for specific diagnosis, regardless of imaging findings 1

Pitfalls to Avoid

• Relying solely on plain radiography, which has limited usefulness and high false-negative rates 1
• Delaying imaging after recent infection (imaging should be performed >2 weeks after upper respiratory tract infection and >4 weeks after acute bacterial sinusitis) 1
• Failing to consider complementary imaging when initial findings are concerning 1
• Misinterpreting inflammatory changes as tumor (MRI can help differentiate) 1