Is MRI with or without contrast better for diagnosing thoracic spine fracture?

MRI Without Contrast is Superior for Diagnosing Thoracic Spine Fractures

MRI without contrast is the preferred imaging modality for diagnosing thoracic spine fractures as it provides excellent visualization of both bony and soft tissue injuries without the need for contrast administration. 1

Imaging Options for Thoracic Spine Fractures

Initial Imaging

• Plain radiographs may serve as an initial screening tool, especially in patients with risk factors for osteoporotic fractures without neurologic deficits
• CT without contrast is useful in emergency settings or for presurgical planning, particularly when radiographs are negative
• MRI without contrast provides superior soft tissue resolution and can identify:
  • Compression fractures (even when radiographs are negative)
  • Marrow edema (helpful for planning interventions)
  • Soft tissue injuries
  • Neurologic compressive injuries

Role of MRI Without Contrast

MRI without contrast is particularly valuable in thoracic spine fractures because:

1. It offers excellent visualization of bone marrow edema, which helps determine fracture acuity
2. It can detect posterior ligamentous complex injuries that may affect stability
3. It directly visualizes effects of fractures on the spinal cord 2
4. It provides superior assessment of soft tissue and neural structures 1

When to Consider MRI With Contrast

MRI with contrast is generally not recommended as a standalone initial study for thoracic spine fractures 1. According to the American College of Radiology guidelines, contrast-enhanced MRI:

• Is not typically performed as an initial study unless there is concern for underlying neoplasm, infection, or inflammation
• Is most informative when correlated with standard non-contrast sequences
• May be helpful in specific scenarios such as:
  • Suspected postoperative infection
  • Hematoma evaluation
  • Assessment of postoperative collections
  • Canal compromise evaluation

Evidence Comparison

Research has shown that MRI with contrast offers no significant advantage over non-contrast MRI in the diagnosis of major traumatic injuries such as hematoma and edema 3. The only advantage of contrast-enhanced MRI is slightly better visualization of soft tissue injuries, but this rarely changes clinical management in acute trauma settings.

A 2019 study found that MRI after CT scan changed clinical management in only 15% of patients with thoracolumbar spine fractures, and in no case did a patient planned for non-operative care require surgery after MRI 4. This suggests that while MRI provides additional information, contrast administration rarely affects treatment decisions.

Clinical Algorithm for Imaging Selection

1. Initial presentation with suspected thoracic spine fracture:

   • Begin with thoracic spine radiography if patient has no neurologic deficits
   • Consider immediate CT without contrast in emergency settings

2. If fracture is confirmed or strongly suspected:

   • Proceed to MRI without contrast to assess:
     • Fracture acuity (marrow edema)
     • Posterior ligamentous complex integrity
     • Spinal cord or nerve root compression
     • Soft tissue injuries

3. Consider MRI with contrast only if:

   • There is suspicion of cancer, infection, or immunosuppression
   • Initial non-contrast MRI shows findings suggestive of infection or tumor
   • Patient has undergone recent spine surgery and postoperative complications are suspected

Common Pitfalls to Avoid

1. Unnecessary contrast administration: Contrast adds time, cost, and potential risks (allergic reactions, nephrogenic systemic fibrosis in renal impairment) without providing significant additional diagnostic information for most traumatic fractures

2. Relying solely on CT: While excellent for bony detail, CT may miss ligamentous injuries and subtle cord abnormalities that could affect management

3. Limited field of view: When performing focused MRI, ensure coverage extends at least three levels above and below the known fracture to avoid missing clinically significant pathology 5

4. Delayed imaging: Acute marrow edema is best visualized within the first 2 weeks after injury; delayed imaging may underestimate fracture acuity

In summary, MRI without contrast provides the most comprehensive assessment of thoracic spine fractures with visualization of both bony and soft tissue injuries, and should be the preferred imaging modality for most patients with suspected thoracic spine fractures.