When is a contrast-enhanced Computed Tomography (CT) scan preferred over a non-contrast CT scan for trauma patients with suspected spine injury?

CT Spine Without Contrast is the Preferred Initial Imaging for Suspected Spine Trauma

For patients with suspected spine trauma, non-contrast CT scan is the recommended initial imaging modality, while contrast-enhanced CT is generally not indicated for the evaluation of acute traumatic spine injuries.

Initial Imaging for Suspected Spine Trauma

Cervical Spine

• CT cervical spine without IV contrast is the recommended initial imaging for patients with suspected acute blunt trauma of the cervical spine when imaging is indicated by NEXUS or CCR clinical criteria 1
• Non-contrast CT provides detailed visualization of bony structures, alignment, and fractures, which are the primary concerns in acute trauma 1
• CT without contrast has become the standard of care for initial spine trauma evaluation due to its superior sensitivity for detecting fractures compared to plain radiographs 2
• CT reconstructions can be performed in multiple planes, allowing for comprehensive assessment of the spine without additional radiation exposure 1

Thoracic and Lumbar Spine

• CT thoracic and lumbar spine without IV contrast is the recommended initial imaging for patients with suspected thoracolumbar trauma 1
• Thoracic and lumbar spine CT reconstructions can be performed from concurrently obtained CT imaging of the thorax, abdomen, and pelvis without additional radiation exposure 1
• This approach is both effective and radiation dose-sparing in trauma patients 1

When is Contrast-Enhanced CT Indicated?

Contrast-enhanced CT is generally not indicated for the initial evaluation of acute spine trauma. The ACR Appropriateness Criteria specifically states:

• CT with IV contrast does not provide additional information to CT without IV contrast for evaluation of spinal fractures and alignment 1
• CT without and with IV contrast of the spine is not typically performed as there is no diagnostic advantage to performing a single study with or without IV contrast 1

When Additional Imaging is Needed After Initial Non-Contrast CT

MRI Without Contrast

• MRI without contrast (not contrast-enhanced CT) is the appropriate next step when there are:
  • Suspected or confirmed spinal cord or nerve root injuries 1
  • Clinical findings suggesting ligamentous injury 1
  • Neurologic abnormalities with acute spine injury detected on CT 1
  • Obtunded patients with suspected spine trauma and negative initial CT (though this remains somewhat controversial) 1

Contrast-Enhanced Vascular Studies

• CTA head and neck with IV contrast is appropriate only when there are clinical or imaging findings suggesting arterial injury 1
• This is the only scenario where contrast administration is routinely recommended in the acute spine trauma setting 1

Diagnostic Performance Considerations

• CT without contrast has high sensitivity (88.6%) and specificity (99%) for detecting traumatic spine injuries 3
• MRI can detect certain injuries missed by CT, particularly soft tissue and ligamentous injuries 4, 3
• CT is superior for detecting vertebral fractures, while MRI is more capable of detecting soft tissue injuries 4
• In a study comparing imaging modalities, MRI identified 14 cases correctly diagnosed as injured that were missed by CT 3

Common Pitfalls to Avoid

• Relying solely on CT when there are neurological deficits or persistent symptoms despite negative CT findings 4, 3
• Using contrast-enhanced CT when non-contrast CT would suffice, unnecessarily exposing patients to contrast media risks 1
• Failing to recognize that isolated unstable ligamentous injury in the absence of fractures is extremely rare in the thoracolumbar spine, making MRI screening unnecessary when CT is normal and there are no neurological symptoms 1
• Overlooking the need for vascular imaging (CTA with contrast) in patients with risk factors for blunt cerebrovascular injury 1

In summary, non-contrast CT is the imaging modality of choice for initial evaluation of suspected spine trauma, while contrast-enhanced CT has limited utility in this setting. MRI without contrast serves as the appropriate next step for evaluating soft tissue injuries, ligamentous damage, and neurological concerns.