What is the recommended imaging protocol for a patient with low back bilateral radiculopathy, specifically whether to use a CT (Computed Tomography) scan with or without contrast?

CT Imaging for Low Back Bilateral Radiculopathy

For patients with low back bilateral radiculopathy, MRI without contrast is the preferred imaging modality, while CT without contrast should be reserved for specific situations when MRI is contraindicated or unavailable. 1

Initial Approach to Imaging for Low Back Radiculopathy

• Imaging is generally not appropriate for acute or subacute low back pain with radiculopathy without red flags and no prior management, as symptoms often resolve with conservative treatment within 4-6 weeks 2
• For patients with persistent symptoms after 6 weeks of optimal medical management who are potential surgical candidates, imaging becomes appropriate 2, 1
• MRI without IV contrast is the preferred initial imaging study for patients with low back radiculopathy who have failed conservative management 1, 3

When to Consider CT for Low Back Radiculopathy

• CT without contrast may be appropriate when MRI is contraindicated (e.g., patients with non-MRI compatible implanted devices) 2
• CT myelography can be useful in patients with significant metallic hardware artifact on MRI, providing excellent visualization of nerve root compression in the lateral recess 2
• CT without contrast provides superior bony detail for evaluating osseous abnormalities that may cause radiculopathy, such as vertebral ring apophyseal fractures in younger patients 4

Contrast Considerations for CT in Radiculopathy

• There is no evidence supporting the use of CT lumbar spine with IV contrast in the initial evaluation of low back pain with radiculopathy without red flags 2
• CT with IV contrast may be useful only when specific conditions are suspected:
  • Epidural abscess or infection 2
  • Post-surgical evaluation when infection is suspected 2
• CT without and with IV contrast is not typically performed as there is no diagnostic advantage to performing a single study with both options 2

Clinical Decision Algorithm

1. First 6 weeks: No imaging unless red flags present; focus on conservative management 2, 1
2. After 6 weeks of failed conservative management:
   • MRI without contrast is first-line imaging 1, 3
   • If MRI is contraindicated: CT without contrast or CT myelography 2
   • CT with contrast only if infection/abscess is suspected 2

Common Pitfalls to Avoid

• Ordering imaging too early (before 6 weeks of conservative management) in the absence of red flags can lead to unnecessary procedures and increased healthcare utilization 1, 5
• Repeat CT scans within 2-3 years rarely provide added diagnostic value for chronic or recurrent low back pain or radiculopathy 6
• Using CT as first-line imaging for radiculopathy when MRI is available and not contraindicated 1
• Adding contrast to CT when not indicated, which increases radiation exposure without diagnostic benefit 2

Red Flags Requiring Urgent Imaging

• Severe or progressive neurologic deficits
• Suspected cauda equina syndrome
• Suspected malignancy
• Suspected infection
• Recent significant trauma 1, 7, 5

In these cases, the appropriate imaging modality and use of contrast should be determined based on the specific clinical concern, with MRI generally preferred for most neurologic conditions 1, 7.