What is a Spine X-ray?
A spine X-ray (radiography) is a projectional imaging technique that uses ionizing radiation to visualize the bony structures of the cervical, thoracic, lumbar spine, or sacrum by detecting differences in electron density between tissues. 1
Technical Overview
Spine radiography is a widely available, rapid imaging modality that provides excellent visualization of osseous anatomy, including vertebral bodies, pedicles, spinous processes, and overall spinal alignment. 1, 2 The technique involves:
- Standard views: Anteroposterior (AP) and lateral projections are obtained for the region of interest 1
- Specialized views: A "swimmer's lateral" view may be added for the upper thoracic spine when obscured by overlying shoulders 1
- Functional imaging: Flexion-extension radiographs can assess spinal stability in subacute or chronic injuries 1
- Radiation exposure: The effective dose is low, approximately equivalent to a chest X-ray for spine imaging 1
Clinical Limitations
Spine X-rays have significant limitations that restrict their clinical utility in many scenarios:
- Poor sensitivity for fractures: Only 49-62% sensitive for thoracic spine fractures and 67-82% sensitive for lumbar spine fractures, compared to 94-100% sensitivity with CT 1, 3
- Cannot visualize soft tissues: Radiographs are insensitive to epidural space pathology, spinal cord compression, disc herniations, ligamentous injuries, and neural structures 1, 3
- Inadequate for neurologic compromise: Not useful as the initial imaging examination when patients present with neurologic deficits or suspected cord compression 1, 3
- Late detection of bone changes: Demineralized bone from osteoporosis or infection is detectable but with substantially lower sensitivity than other modalities 1
Current Clinical Role
Spine radiographs now serve primarily as a complementary imaging tool rather than a primary diagnostic modality in most clinical scenarios:
- Trauma evaluation: CT has largely supplanted radiography for suspected spine trauma due to superior fracture detection 1
- Surgical planning: May help guide imaging evaluation when frank disc and vertebral body involvement is evident, and can assist with surgical management planning 1
- Screening tool: Can serve as an anatomical map before proceeding to advanced imaging like CT or MRI 2
- Osteoporosis assessment: Useful for identifying vertebral compression fractures in patients with risk factors (age, height loss, prior fractures), though dual-energy X-ray absorptiometry (DXA) is preferred for bone density measurement 1, 4
When Advanced Imaging is Preferred
MRI is the gold standard for most spinal pathology requiring soft-tissue evaluation, with 96% sensitivity and 94% specificity for spinal cord compression. 3, 5 CT should be used instead of radiographs when fracture detection is critical, particularly in trauma settings. 1, 3