What it is (overview)

A CT Lumbar Spine without IV contrast (also called a lower back CT, lumbar spine CT plain, or l-spine CT) is an imaging test that uses X-rays and a computer to create detailed cross-sectional pictures of the bones in your lower back (the lumbar vertebrae). “Without IV contrast” means no contrast dye is injected into a vein, so the scan focuses primarily on bone detail and overall spinal structure.

This test helps your clinician evaluate the shape, alignment, and integrity of the lumbar spine, including the vertebral bodies, facet joints, spinal canal, and the openings where nerves travel (neural foramina). CT is especially good at showing fractures, bone spurs, arthritis changes, and certain bony tumors or lesions. While CT can show some information about discs and soft tissues, MRI is typically better for discs, nerves, and the spinal cord.

Results are interpreted by a radiologist. A “normal” result generally means the vertebrae are aligned normally, there are no fractures, no suspicious bone lesions, and no significant narrowing of the spinal canal. An “abnormal” result may describe findings such as a fracture, degenerative (wear-and-tear) changes, narrowed spaces that may affect nerves, or a mass/lesion involving bone. Your provider will combine the CT findings with your symptoms and exam to decide on next steps (for example, physical therapy, medications, referral to a spine specialist, or additional imaging like MRI).

When & why it's usually done

A CT of the lumbar spine without contrast is commonly ordered when a provider needs a fast, detailed look at the bony anatomy of the lower back. It may be used in urgent settings (such as after an injury) or when X-rays don’t provide enough information.

Your clinician may order a lumbar spine CT plain if you have:

Symptoms that may suggest a structural or bony problem, such as:

• Severe or persistent lower back pain, especially after a fall, accident, or other trauma
• Back pain with suspicion for a compression fracture (more likely with osteoporosis or long-term steroid use)
• Back pain with possible spinal instability or abnormal spine alignment
• Back pain with suspected spinal stenosis (narrowing that can contribute to leg pain with walking)

Clinical situations where CT is especially helpful:

• Trauma evaluation to look for fractures or bone fragments
• Pre-surgical planning or detailed anatomy review before spine procedures
• Assessment of degenerative changes (arthritis, bone spurs, facet joint changes)
• Evaluation of suspected bone tumors or abnormal bone lesions (sometimes followed by MRI or biopsy depending on findings)
• Follow-up of certain known spine conditions to check for changes over time

A “no-contrast” lower back CT is often chosen when the main question is about bone (for example, a fracture) or when contrast is not necessary. If your provider is more concerned about infection, inflammation, or certain tumors involving soft tissues, they may recommend CT with contrast or an MRI instead.

Common diseases related to it

• Lumbar spine fractures (including compression fractures)
• Degenerative disc disease and age-related spine changes
• Facet joint osteoarthritis (facet arthropathy)
• Spinal stenosis (narrowing of the spinal canal)
• Spondylolisthesis (one vertebra slipping over another)
• Spondylolysis (stress fracture/defect in part of a vertebra)
• Herniated disc or disc bulge (may be seen, though MRI is often preferred for detail)
• Bone spurs (osteophytes) that may contribute to nerve narrowing
• Spine tumors or suspicious bone lesions (primary or metastatic)
• Scoliosis or other alignment/curvature abnormalities

Health goals where it may help

• Getting an accurate diagnosis for the cause of lower back pain when a bone problem is suspected
• Ruling out or confirming a lumbar fracture after injury to guide safe treatment and activity levels
• Evaluating spine alignment and stability to plan rehabilitation or surgical options
• Assessing the extent of arthritis/degenerative changes to support a long-term back pain management plan
• Supporting decisions about return to work, sports, or physical activity after trauma
• Helping plan or guide spine procedures (for example, certain injections or surgery planning) by providing detailed bony anatomy
• Monitoring known spine abnormalities over time when your care team needs a clear view of bone changes