← Back to Browse
Ask AleraHome
MRI
SpineDemonstration data

Spine MRI (Lumbar)

Lumbar spine MRI is the modality of choice for evaluating the intervertebral discs, spinal canal, neural foramina, conus medullaris, and cauda equina without ionizing radiation. It provides high-contrast depiction of degenerative, inflammatory, neoplastic, and infective processes affecting the lumbar spine. Contrast is reserved for suspected infection, tumor, or postoperative recurrent disc versus scar. It underpins management decisions in radiculopathy, myelopathy, and suspected cord/cauda compromise.

Indications

  • Low back pain with radiculopathy or neurological deficit unresponsive to conservative therapy
  • Suspected lumbar disc herniation, spinal or foraminal stenosis, or spondylolisthesis
  • Cauda equina syndrome (saddle anesthesia, bladder/bowel dysfunction) as an emergency
  • Suspected spinal infection (discitis/osteomyelitis, epidural abscess), especially with fever or raised inflammatory markers
  • Known or suspected malignancy with back pain, to assess metastases or cord/root compression
  • Inflammatory back pain and suspected axial spondyloarthropathy (sacroiliitis)
  • Postoperative assessment for recurrent/residual disc, scar, or complication (with contrast)
  • Trauma when radiographs/CT are equivocal for ligamentous or marrow injury

Contraindications & Cautions

  • Non-MRI-conditional pacemakers, neurostimulators, and other incompatible implanted devices
  • Ferromagnetic surgical hardware may cause substantial artifact though most modern spinal implants are MRI-safe
  • Severe renal impairment (eGFR <30) limits gadolinium use owing to nephrogenic systemic fibrosis risk
  • Gadolinium hypersensitivity
  • Pregnancy: perform non-contrast; avoid gadolinium unless essential
  • Claustrophobia or inability to lie still may require sedation

Patient Preparation

  • Complete MRI safety screening for implants and devices
  • Confirm the clinical question (radiculopathy level, red flags, prior surgery)
  • Check eGFR and obtain contrast consent when gadolinium is planned
  • No fasting required; encourage voiding before a lengthy examination
  • Position supine with knees supported to reduce lumbar lordosis and patient discomfort
  • Establish IV access if contrast anticipated; provide hearing protection and immobilize the patient

Technique & Parameters

  • 1.5T or 3T with a dedicated spine/phased-array coil
  • Sagittal T1 and T2 covering the lower thoracic cord/conus to the sacrum
  • Sagittal STIR or fat-saturated T2 to increase conspicuity of marrow edema and infection
  • Axial T2 (and axial T1) angled through the discs from L2-L3 to S1
  • Slice thickness 3-4 mm with small field of view for the axial stacks
  • Post-gadolinium fat-saturated T1 (sagittal and axial) for infection, tumor, or postoperative studies
  • Consider dedicated oblique coronal STIR of the sacroiliac joints if spondyloarthropathy is suspected

Systematic Review

  • Assess vertebral alignment, height, and any listhesis or transitional anatomy (label carefully)
  • Review vertebral marrow signal for infiltration, edema, or Modic degenerative change
  • Evaluate each disc for hydration, height, bulge, protrusion, extrusion, or migration
  • Assess the central canal and lateral recesses for stenosis at every level
  • Trace exiting and traversing nerve roots through the neural foramina
  • Examine the conus medullaris position and morphology and the cauda equina
  • Inspect the facet joints, ligamentum flavum, and posterior elements
  • Review paraspinal soft tissues, sacrum, and incidental retroperitoneal/pelvic findings

Key Findings & Significance

  • Disc extrusion contacting or displacing a traversing nerve root explains radicular pain
  • Central canal narrowing with CSF effacement and crowded cauda equina indicates stenosis
  • Disc/endplate T2 hyperintensity with marrow edema and enhancement suggests discitis-osteomyelitis
  • Rim-enhancing epidural collection compressing the thecal sac indicates epidural abscess
  • Focal marrow replacement (low T1, high STIR, enhancing) suggests metastasis or myeloma
  • Pars defect with anterolisthesis indicates spondylolysis/isthmic spondylolisthesis
  • Conus terminating below L2 with a thickened filum suggests tethered cord

Differential Considerations

  • Radiculopathy: disc herniation, foraminal stenosis, synovial cyst, nerve sheath tumor
  • Marrow edema: infection, fracture, Modic type 1 change, metastasis, spondyloarthropathy
  • Epidural mass: abscess, metastasis, hematoma, extruded disc fragment, lymphoma
  • Multilevel stenosis: degenerative, congenital short pedicles, achondroplasia, epidural lipomatosis
  • Enhancing intradural lesion: schwannoma, meningioma, myxopapillary ependymoma, drop metastasis
  • Postoperative enhancing tissue: scar/granulation (diffuse) versus recurrent disc (peripheral rim)

Pearls & Pitfalls

  • Correlate imaging level with clinical dermatome; degenerative findings are common and often incidental
  • Distinguish recurrent disc from epidural fibrosis using contrast: scar enhances diffusely, disc has a nonenhancing center
  • STIR/fat-sat T2 is key to unmasking subtle marrow edema and early infection
  • Beware transitional vertebrae; miscounting levels is a common and consequential error
  • In cauda equina syndrome, assess the full thecal sac and communicate urgently
  • Facet and epidural fat can mimic hemorrhage; verify with fat-saturation
  • Conjoined nerve roots can mimic disc herniation on axial images

Structured Report

  • State indication, technique, contrast use, and comparison studies
  • Report alignment, marrow signal, and conus level
  • Describe disc pathology and canal/foraminal stenosis level by level using standardized nomenclature
  • Specify nerve root impingement and grade of central canal stenosis
  • Note infection, tumor, fracture, or postoperative findings explicitly
  • Impression: correlate the dominant level with the clinical deficit and flag emergencies
  • Recommend surgical/specialist correlation or urgent action where cauda equina or cord compromise is present

References

  • ACR-ASNR-SCBT-MR Practice Parameter for MRI of the Adult Spine
  • ACR Appropriateness Criteria: Low Back Pain
  • Fardon et al., Lumbar Disc Nomenclature 2.0 (NASS/ASSR/ASNR)
  • ASSR/Pfirrmann disc degeneration grading and Modic endplate classification literature
  • RadioGraphics reviews on spinal infection and postoperative spine imaging

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