When should a computed tomography (CT) scan be ordered for a patient with an acute back injury?

CT Imaging for Acute Back Injury: When to Order

CT scans should only be ordered for acute back injury when specific "red flags" are present, including significant trauma, neurological deficits, suspected fracture, or signs of spinal cord compression.

Indications for CT Imaging in Acute Back Injury

CT is the gold standard for identifying spine fractures with a reported sensitivity of 94-100%, significantly outperforming radiographs 1. However, imaging should be selective and based on clinical findings.

Definite Indications for CT Imaging:

• Major trauma mechanism: Fall from height, motor vehicle crash, high-energy impact 1
• Neurological deficits: Motor weakness, sensory changes, or abnormal reflexes 1
• Signs of spinal cord compression: Bowel/bladder dysfunction, saddle anesthesia 1
• High-risk patient factors:
  • Age >60 years 1
  • Known osteoporosis or pathologic fracture risk
  • History of malignancy with potential bone metastasis
  • Ankylosing spinal disorders 2
  • Immunosuppression or suspected infection

Clinical Assessment Criteria:

For thoracolumbar injuries, any of the following should prompt CT imaging 1:

• Midline thoracolumbar tenderness
• Painful distracting injury
• Altered mental status (GCS <15)
• Intoxication preventing reliable examination
• High-risk mechanism of injury

When NOT to Order CT Imaging

• Acute uncomplicated low back pain (<4 weeks duration) without red flags 1
• Mechanical back pain with no trauma history or neurological symptoms 1
• Routine follow-up of known back conditions without new symptoms 3

Appropriate Imaging Pathway

1. Initial assessment: Evaluate for red flags and neurological deficits
2. If red flags present: Order CT spine without contrast as first-line imaging 1
3. If neurological deficits or soft tissue injury suspected: Follow CT with MRI 1

Special Considerations

• CT is superior to radiographs for detecting spine fractures and has largely replaced them in trauma settings 1
• Consider imaging the entire spine in trauma cases, as approximately 20% of patients have non-contiguous injuries 1
• MRI is complementary to CT and should be performed when there is:
  • Suspected spinal cord injury
  • Neurological deficit without clear CT findings
  • Concern for ligamentous instability, disc herniation, or epidural hematoma 1

Common Pitfalls to Avoid

• Overutilization of imaging for acute, non-specific back pain without red flags 1
• Relying solely on radiographs which have poor sensitivity (49-82%) for thoracolumbar fractures 1
• Failure to obtain MRI when neurological deficits are present but CT is negative 1
• Unnecessary repeat imaging for chronic symptoms without clinical change 3

CT imaging for acute back injury should be reserved for cases with specific clinical indicators suggesting serious pathology, as routine imaging in uncomplicated cases does not improve outcomes and increases healthcare costs 1, 4.