Can an MRI be performed after cervical fusion?

MRI After Cervical Fusion: Safety and Clinical Utility

MRI can be safely performed after cervical fusion, though it has limitations due to metal artifact from hardware that may compromise image quality, making CT the preferred modality for assessing fusion status and hardware integrity. 1

Safety and Technical Considerations

• MRI is safe to perform after cervical fusion, but metal artifact significantly limits assessment of the fused level and hardware integrity 1
• Modern MRI sequences with metal artifact reduction techniques can improve image quality, though these specialized protocols may not be available at all imaging centers 1
• Titanium hardware produces less artifact than stainless steel implants, allowing for better visualization of surrounding structures 1
• The American College of Radiology recommends CT as the gold standard for assessment of spinal fusion and hardware integrity due to superior visualization of bony structures 1

Clinical Utility of MRI After Cervical Fusion

• MRI remains the most sensitive imaging test for detecting soft tissue abnormalities associated with neck pain despite hardware limitations 1
• MRI offers significant benefit in detecting adjacent level disease including disc herniations and nerve root impingement in post-surgical patients 1
• For patients with new neurological symptoms after fusion, MRI can effectively evaluate the spinal cord and nerve roots at non-instrumented levels 2
• Early postoperative MRI (within 30 days) can be interpretable and useful for investigating neurological complaints following anterior cervical discectomy and fusion 2

Imaging Protocol Recommendations

• MRI without contrast is appropriate for evaluating adjacent segment disease and soft tissue complications 1
• MRI with and without contrast is the preferred imaging modality when infection is suspected 1
• Contrast enhancement is not routinely needed for anterior approach surgeries since the epidural space is rarely transgressed 1
• Kinematic MRI can be used to measure range of motion with high precision (less than 3 degrees) after spinal fusion to assess adjacent segment biomechanics 3

Alternative Imaging Modalities

• CT is considered superior to MRI for assessing fusion status and hardware integrity 4
• CT offers significant advantages over radiographs in detecting adjacent segment degenerative disease, with studies showing CT altered treatment in 60% of patients with abnormal imaging and persistent symptoms 1
• Plain radiographs should be the initial modality for determining cervical fusion status, with less than 1mm motion on flexion-extension views suggesting solid fusion 5
• If radiographs are indeterminate, CT is recommended as the next step due to its relatively high accuracy and reliability 5

Common Pitfalls and Considerations

• Degenerative findings on MRI are commonly observed in asymptomatic patients, with approximately 65% of asymptomatic patients 50-59 years of age having radiographic evidence of significant cervical spine degeneration 1
• Metal artifact from hardware can create false positives for pathology, particularly at the level of fusion 1
• The presence of a solid fusion on imaging does not necessarily correlate with symptom resolution, as patients may have persistent symptoms despite radiographic evidence of fusion 6
• When evaluating for pseudarthrosis, CT scanning is considered the most sensitive and specific modality, as MRI may be limited by hardware artifact 6