MRI Lumbar Spine: With or Without Contrast
For most lumbar spine indications, you should get an MRI WITHOUT contrast, as it provides excellent visualization of disc herniations, spinal stenosis, and nerve root compression—the most common causes of low back pain. 1, 2
Clinical Decision Algorithm
Start with MRI WITHOUT Contrast for:
- Subacute or chronic low back pain with persistent symptoms after 6 weeks of conservative management 1
- Suspected cauda equina syndrome (MRI without contrast accurately depicts soft-tissue pathology and spinal canal patency) 1
- Radiculopathy or sciatica requiring surgical evaluation 1
- Degenerative disc disease with multilevel disc narrowing and facet joint hypertrophy 3
- Trauma without suspicion of infection or malignancy 1
MRI without contrast effectively visualizes disc herniation, spinal stenosis, nerve root compression, and vertebral marrow abnormalities using T1-weighted and short tau inversion recovery sequences. 1, 2
Add Contrast (MRI With AND Without Contrast) for:
You need contrast when there are "red flag" conditions that require distinguishing between different tissue types or evaluating disease extent: 1
- Suspected cancer or metastatic disease (contrast helps distinguish benign from malignant lesions and visualizes epidural tumor extension with high spatial resolution) 1
- Suspected infection or epidural abscess (contrast distinguishes abscess from phlegmon and assesses epidural/paravertebral involvement) 1
- Immunosuppression (higher risk of occult infection or malignancy) 1
- Prior lumbar surgery with new or progressive symptoms (contrast accurately distinguishes recurrent disc herniation from postoperative scar tissue and evaluates for arachnoiditis) 1, 2
Important Caveats
When MRI Without Contrast May Be Sufficient Even with Red Flags:
If there is LOW risk of epidural or intraspinal disease, MRI without contrast can be sufficient even when evaluating for malignancy, as noncontrast sequences can distinguish benign from malignant bone marrow abnormalities. 1
Never Order Contrast Alone:
MRI with contrast alone (without the noncontrast sequences) should never be ordered as an initial study, as interpretation requires correlation with standard noncontrast sequences. 1
Equivalent Alternatives:
The American College of Radiology considers MRI with and without contrast and MRI without contrast as equivalent alternatives for suspected cauda equina syndrome, meaning either approach is appropriate. 1
Practical Considerations
- No radiation exposure with MRI makes it safer than CT for degenerative spine evaluation 3
- If MRI is contraindicated, CT myelography is an appropriate alternative but requires lumbar puncture for intrathecal contrast injection 1, 3
- Imaging findings must correlate with clinical symptoms, as disc abnormalities are common in asymptomatic individuals 2, 4