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SpineDemonstration data

CT Spine (Lumbar)

CT of the lumbar spine provides high-resolution osseous detail of the vertebrae, facet joints, and neural foramina, making it valuable for trauma, degenerative disease, and preoperative/postoperative surgical planning. It excels at characterizing fractures, bony canal compromise, hardware, and calcified disc disease, and serves as the primary study when MRI is contraindicated. MRI remains superior for cord, soft tissue, and marrow evaluation, so the two are frequently complementary.

Indications

  • Lumbar spine trauma to detect and characterize fractures and alignment
  • Radiculopathy or back pain when MRI is contraindicated or as a bony adjunct
  • Preoperative planning and postoperative hardware/fusion assessment
  • Suspected spondylolysis, facet arthropathy, and degenerative canal/foraminal stenosis
  • Suspected infection (spondylodiscitis) or bony tumor/metastasis (with contrast as needed)
  • Evaluation of failed back surgery and pseudarthrosis

Contraindications & Cautions

  • No absolute contraindication for the standard non-contrast study
  • Pregnancy: justify carefully given gonadal proximity; prefer MRI where feasible
  • Radiation dose to gonads and marrow warrants ALARA technique, especially in young patients and repeat imaging
  • Iodinated contrast (for infection/tumor) requires renal function and allergy screening
  • MRI is preferred when cord/soft-tissue, marrow, or radiculopathy detail is the primary question

Patient Preparation

  • No fasting for non-contrast CT; screen renal function and allergy if contrast is planned
  • Position supine with knees flexed over a bolster to reduce lumbar lordosis
  • Immobilize trauma patients and maintain spinal precautions during transfer and scanning
  • Remove metallic objects (belts, piercings) from the field to limit artifact
  • Explain breath-hold at the diaphragmatic levels to reduce motion
  • Confirm the clinical question and levels of interest and any prior imaging

Technique & Parameters

  • Thin-section helical acquisition (0.6-1.25 mm) covering the levels of interest, typically T12 to S1
  • Reconstruct overlapping axial images with sagittal and coronal reformats in bone and soft-tissue algorithms
  • Bone algorithm/kernel for cortical detail; soft-tissue windows for discs, canal contents, and paraspinal structures
  • 120 kVp with tube-current modulation; add metal-artifact reduction reconstruction for instrumented spines
  • Add IV contrast for suspected infection or tumor to assess enhancement and epidural/paraspinal collections
  • Review at bone (W2000/L400-500) and soft-tissue windows; angled reformats along disc spaces for foramina

Systematic Review

  • Assess vertebral alignment on sagittal reformats (anterior/posterior lines, spinolaminar line)
  • Evaluate each vertebral body and posterior elements for fractures and lytic/sclerotic lesions
  • Review disc spaces for height loss, vacuum phenomenon, calcification, and herniation
  • Assess the central canal and lateral recesses for stenosis (bony and calcified disc contribution)
  • Examine neural foramina on angled/sagittal reformats for narrowing
  • Inspect facet joints for arthropathy, effusion, and the pars interarticularis for defects
  • Review paraspinal soft tissues, psoas, and any hardware position/integrity

Key Findings & Significance

  • Vertebral fracture with retropulsed fragment and canal compromise (burst vs compression pattern)
  • Pars interarticularis defect (spondylolysis) with or without spondylolisthesis
  • Facet and ligamentum flavum hypertrophy causing central/lateral recess stenosis
  • Calcified or ossified disc herniation narrowing the canal or foramen
  • Endplate erosion with disc-space narrowing and paravertebral collection: spondylodiscitis
  • Lytic or sclerotic osseous lesions suggesting metastasis or primary bone tumor
  • Hardware loosening, malposition, or lucency around a fusion suggesting pseudarthrosis

Differential Considerations

  • Vertebral collapse: osteoporotic vs pathologic (malignant) vs traumatic vs infective
  • Endplate destruction: infection (spondylodiscitis) vs erosive osteochondrosis vs neoplasm
  • Sclerotic vertebral lesion: bone island vs osteoblastic metastasis vs Paget disease vs hemangioma
  • Canal narrowing: degenerative bony/disc stenosis vs congenital short pedicles vs epidural mass
  • Spondylolisthesis: isthmic (pars defect) vs degenerative (facet arthropathy)
  • Paraspinal mass: abscess vs hematoma vs tumor extension

Pearls & Pitfalls

  • Sagittal and coronal reformats are essential; subtle fractures and listhesis are missed on axial images alone
  • Look specifically for the pars defect on angled/oblique reformats ('Scotty dog' neck)
  • Retropulsion of the posterior vertebral cortex distinguishes an unstable burst from a simple compression fracture
  • CT underestimates soft-tissue and ligamentous injury and cord compromise; MRI is complementary
  • Use metal-artifact reduction and adjust windows to assess hardware and adjacent bone
  • Do not overlook the visualized abdominal aorta, kidneys, and lung bases for incidental pathology

Structured Report

  • State technique, levels covered, contrast use, and comparison studies
  • Report alignment, fractures (type, stability, canal compromise), and any listhesis with grade
  • Describe degenerative changes per level: disc, canal, recess, foramen, and facets
  • Comment on marrow/osseous lesions, infection signs, and paraspinal soft tissues
  • Document hardware position, integrity, and fusion status where relevant
  • Impression: prioritized findings, stability/neural compromise, and recommendations (MRI, surgical referral)

References

  • ACR Appropriateness Criteria: Low Back Pain; Suspected Spine Trauma
  • AOSpine Thoracolumbar Spine Injury Classification System
  • ACR-ASNR-SPR Practice Parameter for the Performance of CT of the Spine
  • Ross & Moore, Diagnostic Imaging: Spine

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.