What is the order of tests for diagnosing a back injury?

Diagnostic Testing Order for Back Injury

For suspected back injury, CT scan should be the first-line imaging test, followed by MRI for further assessment of soft tissue structures, with radiographs largely being supplanted by these advanced imaging modalities. 1

Initial Assessment and Imaging Algorithm

Step 1: Clinical Evaluation

• Assess for red flags requiring immediate imaging:
  • Neurological deficits (focal weakness, sensory changes)
  • Constant/night pain lasting ≥4 weeks
  • Radicular symptoms
  • Fever or other signs of infection
  • History of trauma, cancer, IV drug use, immunosuppression

Step 2: First-Line Imaging

• CT Spine (without contrast)
  • Gold standard for identifying spine fractures 1
  • Superior to radiographs for detecting bony injuries 1
  • Useful in acute setting to detect fracture, subluxation, and dislocation requiring immediate stabilization 1
  • Can be performed rapidly while maintaining spine stabilization in trauma cases

Step 3: Second-Line Imaging

• MRI Spine (without contrast)
  • Complementary to CT for detailed assessment of soft tissues 1
  • Essential for evaluating:
    • Ligamentous integrity
    • Intervertebral disc injury
    • Spinal cord injury
    • Epidural abscess or discitis (if infection suspected) 1
  • Performed after CT in trauma setting due to stabilization concerns 1

Step 4: Additional Imaging (Based on Specific Clinical Concerns)

• CTA Neck/Spine

  • Indicated if vascular injury is suspected based on trauma mechanism 1
  • Evaluates carotid/vertebral arteries and anterior spinal artery 1

• MRA Neck

  • For evaluation of cervical arteries if dissection is suspected 1
  • Can be performed with or without contrast 1

Special Considerations

Trauma Patients

• CT is the first-line test for spine trauma, with radiographs largely supplanted 1
• Consider imaging the entire spine in trauma cases, as 20% of patients have noncontiguous injuries 1
• For patients ≥65 years, lower threshold for imaging even with minimal symptoms 1

Suspected Infection

• MRI is the preferred initial test for suspected spine infection 1
• Look for epidural abscess, discitis, or osteomyelitis
• Laboratory tests (ESR, CRP, WBC) should guide imaging decisions 1

Pediatric Patients

• More conservative approach to imaging is recommended 1
• Radiographs may be appropriate initial imaging for children with persistent symptoms 1
• Reserve advanced imaging for persistent pain with concerning clinical findings 1

Common Pitfalls to Avoid

1. Relying solely on radiographs - They are insufficient to evaluate causes of spinal cord compression and have been largely supplanted by CT for trauma 1

2. Delaying imaging in patients with neurological deficits - Immediate imaging is required when neurological deficits are present 1

3. Unnecessary imaging for acute, non-specific back pain - Most pediatric and many adult cases of back pain are mechanical and respond to conservative treatment without imaging 1

4. Overlooking non-contiguous injuries - When one spine fracture is found, consider imaging the entire spine 1

5. Using CT myelography as initial test - There is no evidence supporting CT myelography as the initial imaging test for post-traumatic evaluation 1