Can a patient with a history of spinal fusion and hardware (e.g. titanium or stainless steel) implantation undergo a Magnetic Resonance Imaging (MRI) of the lumbar spine?

MRI of the Lumbar Spine with Spinal Fusion Hardware

Direct Answer

Yes, patients with spinal fusion hardware can safely undergo MRI of the lumbar spine, and MRI remains the preferred imaging modality for evaluating new or progressive symptoms after lumbar fusion surgery. 1

Safety Considerations

Modern spinal fusion hardware, particularly titanium constructs, is MRI-safe and does not pose a contraindication to MRI at 1.5T or less. 1, 2

• Titanium implants are biologically inert and structurally smooth, making them the optimal choice for spinal instrumentation and safe for MRI 1
• Studies demonstrate that patients with implantable spinal fusion hardware can undergo MRI procedures at 1.5T without substantial adverse events or safety concerns 2
• There are no changes in the operation or integrity of spinal fusion hardware after MRI exposure 2

Imaging Protocol Selection

When to Use MRI Without and With Contrast

For patients with prior lumbar surgery and new or progressive symptoms, MRI lumbar spine without and with IV contrast is the most useful initial imaging study. 1

• Contrast administration accurately distinguishes recurrent or residual disc herniations from postoperative scar tissue 1, 3
• Contrast helps evaluate nerve root compression or arachnoiditis in the post-surgical spine 1, 3
• Contrast is essential for identifying and evaluating the extent of infection, including epidural abscess 1, 3

Limitations Due to Metal Artifact

The primary limitation of MRI in patients with spinal hardware is metal-induced artifact that can obscure anatomic detail, not safety concerns. 1, 4

• Metal implants produce geometric distortion known as susceptibility artifact that can limit diagnostic quality 5
• Artifacts are well-characterized and typically do not create insurmountable diagnostic problems 2
• The artifact effect is generally localized to the immediate vicinity of the hardware 6, 4

Alternative Imaging When MRI is Limited

CT Myelography as Primary Alternative

When metallic artifact significantly limits MRI diagnostic quality, CT myelography is the preferred alternative imaging modality. 1, 5

• CT myelography effectively assesses spinal canal patency, neural foramina, and nerve root compression despite the presence of hardware 1, 5
• CT myelography is occasionally more accurate than MRI in diagnosing nerve root compression in the lateral recess, particularly when hardware artifact is present 1, 5
• The disadvantage is the requirement for lumbar puncture and intrathecal contrast injection 1, 5

CT Without Contrast for Specific Indications

CT lumbar spine without IV contrast is useful for evaluating hardware integrity and bony fusion status. 1, 5

• CT detects hardware failure including prosthetic loosening, malalignment, or metallic fracture 1, 5
• CT is equal to MRI for predicting significant spinal stenosis and excluding cauda equina impingement 1, 5
• CT provides less detailed soft tissue information compared to MRI or CT myelography 5

Complementary Plain Radiography

Plain radiographs are complementary to advanced imaging and useful for evaluating alignment and hardware integrity. 1

• Upright radiographs provide functional information about axial loading 1
• Flexion-extension views can detect abnormal motion or increased dynamic mobility 1
• Static radiographs alone are insufficient for comprehensive evaluation, with only 64-69% correlation with surgical findings 1

Clinical Decision Algorithm

Step 1: Determine Clinical Indication

• New or progressive radiculopathy after fusion → MRI with and without contrast 1, 3
• Suspected infection or abscess → MRI with and without contrast 1, 3
• Hardware integrity concerns → CT without contrast 1, 5
• Fusion status assessment → CT without contrast 1, 5

Step 2: Assess MRI Feasibility

• Confirm hardware type (titanium preferred and MRI-safe) 1, 2
• If significant artifact expected or MRI contraindicated → proceed to CT myelography 1, 5
• If MRI-conditional hardware → use metal artifact reduction sequences if available 5

Step 3: Interpret Results in Context

• Correlate imaging findings with clinical symptoms, as disc abnormalities are common in asymptomatic individuals 3
• Consider multi-modality approach when initial imaging is inconclusive 1, 6

Common Pitfalls to Avoid

• Do not assume all spinal hardware is MRI-unsafe – modern titanium constructs are MRI-compatible at 1.5T or less 1, 2
• Do not rely on plain radiographs alone – they have only 64-69% accuracy for detecting complications and significant interobserver variability 1
• Do not skip contrast in post-surgical patients with new symptoms – contrast is essential for distinguishing scar from recurrent disc herniation 1, 3
• Do not use Tc99m bone scanning as primary diagnostic tool – it has poor sensitivity (50%) for detecting pseudarthrosis 1