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.

Spine MRI (Lumbar)

📋 Indications

⛔ Contraindications & Cautions

🧑‍⚕️ Patient Preparation

⚙️ Technique & Parameters

🔎 Systematic Review

🩻 Key Findings & Significance

🧠 Differential Considerations

💡 Pearls & Pitfalls

📝 Structured Report

📚 References