• A large volume of people expect imaging following injury, believing that finding the cause of the pain will allow more accurate and treatment
  • Many people without symptoms show abnormalities on X-rays and MRI
  • The chance of finding coincidental disc prolapse increases with age.
  • It is important to correlate MRI findings with age and clinical signs
  • In those who have NEVER experienced LBP:
    • 65% over 50 years of age will show abnormalities on plain x-rays, 33% will show evidence of disc abnormality on MRI
    • 20% under 60 showing evidence of a herniated disk.

LBP WITHOUT Radicular Pain

  • Most patients with LBP generally do not require imaging
  • Patients with LBP who MAY require imaging include:
    • Significant trauma
    • History of malignancy
    • Osteoporosis or long term corticosteroid use
    • > 70 years
    • Unexplained LOW
    • Unexplained fever
    • IV drug use
    • Immunosuppression

LBP WITH Radicular Pain

  • Most patients with radicular pain generally do not require imaging UNLESS:
    • No improvement after 6-12 weeks
    • If surgery is being considered
    • Presence of motor signs or bladder dysfunction
    • Recurrent or persistent back pain and radiculopathy  post surgery

**Bladder dysfunction, usually retention (post void residual volume >150mls), is usually an indication for urgent imaging


  • Plain Films
    • The option of choice for patients > 70, with a history of osteoporosis or prolonged corticosteroid treatment, or recent significant trauma.
    • If normal, there is usually no need for further imaging
  • Magnetic Resonance Imaging
    • MRI is the investigation of choice for:
    • Patients with LBP and radiculopathy requiring radiological investigation
    • Suspected spinal infection
    • Suspected metastatic disease with normal RNI
    • Post operative lumbar spine
  • Computerised Tomography
    • Plain CT is an alternative to MRI and is useful for patients with suspected spinal canal stenosis, spinal fractures requiring further evaluation or bone abnormalities on plain film
    • CT myelography is the investigation of choice for patients who should have MRI but contraindicated (eg pacemaker)
  • Bone Scan
    • Most useful in screening patients with known malignancy for metastases.