MRI Without Contrast for Lumbar Spine Stenosis
For evaluating lumbar spine stenosis, MRI lumbar spine WITHOUT IV contrast is the recommended imaging modality and is typically sufficient for diagnosis and surgical planning. 1
Primary Imaging Recommendation
MRI lumbar spine without IV contrast is the first-line and preferred imaging modality for evaluating lumbar spinal stenosis due to its superior soft-tissue contrast and ability to accurately depict nerve root compression, assess the thecal sac, neural structures, and spinal canal patency. 1, 2
Non-contrast MRI provides all necessary diagnostic information for identifying stenosis severity, nerve root compression, disc pathology, and ligamentum flavum hypertrophy without requiring IV contrast administration. 3
The American College of Radiology consistently rates MRI lumbar spine without IV contrast as "usually appropriate" (rating 8-9) for stenosis evaluation, while MRI with contrast receives significantly lower appropriateness ratings (4-6) for this indication. 3
When to Add Contrast
Contrast is NOT routinely needed for stenosis evaluation but should be added only in specific clinical scenarios:
Post-surgical patients with new or progressive symptoms: Contrast is essential to distinguish recurrent/residual disc herniation from postoperative epidural fibrosis (scar tissue), which cannot be reliably differentiated on non-contrast sequences. 1, 3
Suspected infection or malignancy: Add contrast when clinical suspicion exists for epidural abscess, discitis, osteomyelitis, or neoplastic disease as the underlying cause of stenosis. 1, 3
Indeterminate non-contrast studies: If the non-contrast MRI is technically inadequate or clinically inconclusive, contrast may help clarify the diagnosis. 1, 3
Alternative Imaging Modalities
When MRI is contraindicated or unavailable:
CT lumbar spine without IV contrast is equal to MRI for predicting significant spinal stenosis and excluding cauda equina impingement, with 100% sensitivity and 60-83% specificity compared to MRI. 1, 2
CT without contrast showing <50% thecal sac effacement reliably excludes cauda equina impingement with a negative predictive value of 0.99, while ≥50% effacement predicts significant stenosis with 98% sensitivity. 2
CT myelography can assess spinal canal patency and neural foramen in patients with MRI-incompatible devices or significant metallic artifact, though it requires lumbar puncture and intrathecal contrast injection. 1
Common Pitfalls to Avoid
Do not routinely order MRI with contrast for uncomplicated stenosis evaluation – there is no evidence supporting added diagnostic benefit, and it increases cost, scan time, and contrast exposure risk. 1
Avoid CT with IV contrast – there is no relevant literature supporting its use for stenosis evaluation. 1
Do not use plain radiography alone for stenosis assessment, as it is insensitive to epidural space pathology and cannot evaluate soft tissue compression. 1, 2
Be aware that supine MRI may underestimate stenosis severity in some patients, as axial loading and positional changes can significantly alter canal dimensions; dynamic myelography may detect stenosis missed on supine MRI in up to 23% of cases. 4, 5