What imaging studies are typically obtained before orthopedic spinal surgery?

Preoperative Imaging for Orthopedic Spinal Surgery

MRI of the spine without IV contrast is the initial imaging modality of choice for patients being considered for spinal surgery, complemented by upright radiographs with flexion/extension views and CT without contrast for preoperative planning. 1

Primary Imaging Studies

MRI Without IV Contrast

• MRI is the cornerstone of preoperative spinal imaging because it provides excellent soft-tissue contrast and accurately depicts disc degeneration, the thecal sac, neural structures, and potential compressive pathology 1
• For lumbar spine surgery candidates, MRI identifies actionable pain generators that can be targeted for surgical intervention 1
• For thoracic spine surgery, MRI without contrast evaluates compressive etiologies affecting the spinal cord (myelopathy) or nerve roots (radiculopathy) 1
• Important caveat: Many MRI abnormalities appear in asymptomatic individuals, so findings must correlate with clinical presentation 1

Radiography (X-rays)

• Upright radiographs provide essential functional information about axial loading that MRI cannot capture 1
• Flexion and extension radiographs are essential to identify segmental motion, which is critical for surgical management of spondylolisthesis 1
• Lateral bending images are helpful in spinal deformity correction surgery planning 1
• For pediatric scoliosis, PA (not AP) radiographs should be obtained to reduce breast radiation dose 1
• Radiographs assess hardware position and integrity, fusion status, and spinal alignment in postoperative follow-up 1

CT Without IV Contrast

• CT is useful for preoperative planning because it delineates osseous margins and aids in trajectory planning for hardware fixation 1
• CT assesses facets and neural foramina and is equal to MRI for predicting significant spinal stenosis 1
• For pediatric scoliosis, multiplanar and 3-D reconstruction CT helps with presurgical planning and can be used for surgical navigation 1
• CT is particularly valuable when metallic hardware causes significant MRI artifact 1

Specialized Imaging Studies

CT Myelography

• CT myelography is useful when MRI is contraindicated (patients with non-MRI-safe implanted devices) or when significant metallic artifact degrades MRI quality 1
• It assesses patency of the spinal canal/thecal sac, subarticular recesses, and neural foramina 1
• Major disadvantage: Requires lumbar puncture for intrathecal contrast injection 1
• May be appropriate for thoracic spine surgery when compressive etiology is suspected 1

MRI With and Without IV Contrast

• Not routinely used for standard preoperative planning 1
• Reserved for specific scenarios: suspected tumor, infection, postoperative complications (hematoma, abscess, collections), or canal compromise 1
• For congenital scoliosis, routine preoperative MRI may identify neural axis anomalies (hydrosyringomyelia, Chiari malformation, cord tethering) present in >20% of such patients 1

SPECT/CT Bone Scan

• Limited role in preoperative evaluation but may help identify pain sources related to facet arthropathy or sacroiliac joint dysfunction 1
• SPECT bone scan is the reference standard for detecting radiographically occult active spondylolysis in young patients 1
• For pediatric painful scoliosis, bone scintigraphy is sensitive for primary bone tumors (osteoid osteoma, osteoblastoma), spondylolysis, and infection 1

Osteoporosis Assessment

Preoperative Bone Density Evaluation

• Patients with suspected osteoporosis should undergo preoperative assessment with DEXA scan, CT Hounsfield units, or serum vitamin D3 levels 1
• DEXA T-score <−2.5, CT Hounsfield units <97.9, or vitamin D3 <20 ng/mL predict increased risk of postoperative adverse events in patients undergoing spinal instrumentation 1
• Patients with confirmed osteoporosis should be counseled about increased risk of pseudarthrosis, instrumentation failure, and proximal junctional failure 1

Common Pitfalls to Avoid

• Do not rely on radiography alone for surgical planning—it is insufficient without MRI and/or CT imaging 1
• Do not obtain MRI with contrast routinely—it adds cost and time without benefit unless infection or tumor is suspected 1
• Do not skip flexion/extension radiographs—they provide critical information about segmental instability that static imaging cannot reveal 1
• Do not assume all MRI findings are clinically significant—correlation with symptoms is essential since asymptomatic abnormalities are common 1
• For pediatric patients, use PA rather than AP technique and employ low-dose protocols to minimize radiation exposure 1

Algorithm for Imaging Selection

1. Start with MRI without contrast for all surgical candidates to evaluate soft tissue pathology, neural compression, and disc disease 1
2. Add upright radiographs with flexion/extension views to assess functional stability and segmental motion 1
3. Obtain CT without contrast for detailed bony anatomy and hardware trajectory planning 1
4. Consider CT myelography only if MRI is contraindicated or degraded by artifact 1
5. Add contrast-enhanced MRI only when infection, tumor, or postoperative complications are suspected 1
6. Assess bone density (DEXA, CT HU, or vitamin D3) in patients at risk for osteoporosis before instrumentation 1