MRI LUMBO SACRAL SPINE

MRI of the Lumbo-Sacral Spine is a non-invasive imaging procedure that evaluates the lumbar (lower back) and sacral (pelvic) segments of the spinal column. These regions bear the body’s weight, provide mobility, and protect the lower portion of the spinal cord and nerve roots. MRI uses a strong magnetic field and radiofrequency pulses to create high-resolution, multiplanar images of vertebrae, intervertebral discs, spinal cord, nerve roots, ligaments, muscles, and surrounding soft tissues without using ionizing radiation. It is the preferred technique for detecting disc pathology, nerve compression, spinal canal narrowing, inflammatory changes, tumors, infections, and postoperative complications in the lower spine.

Purpose of MRI of Lumbo-Sacral Spine

1. Low back pain evaluation

• Investigation of chronic or acute pain not improving with conservative management.
• Differentiation between musculoskeletal and neurological causes.

2. Radiculopathy (sciatica) assessment

• Identification of nerve root compression causing pain radiating to the legs.
• Assessment of associated weakness, numbness, or tingling.

3. Spinal stenosis

• Evaluation of narrowing of the spinal canal or neural foramina.
• Detection of nerve impingement from bony overgrowth or disc bulges.

4. Trauma-related injuries

• Detection of fractures, ligament tears, or spinal cord injury following accidents.

5. Tumors

• Detection of primary tumors of vertebrae, spinal cord, or nerve roots.
• Identification of metastatic spread from cancers such as breast, lung, or prostate.

6. Infections

• Evaluation of osteomyelitis, discitis, and epidural abscesses.

7. Inflammatory or demyelinating disorders

• Assessment of conditions like multiple sclerosis, arachnoiditis, or transverse myelitis.

8. Postoperative evaluation

• Monitoring after lumbar surgery for disc removal, fusion, or decompression.
• Detection of recurrent disc herniation or scar tissue formation.

Procedure for MRI of Lumbo-Sacral Spine

Before the scan

• Complete medical history is taken, including symptoms, prior back injuries, surgeries, and existing medical conditions.
• Patients must remove jewelry, belts, watches, and other metal objects.
• Any metallic implants must be disclosed to ensure MRI compatibility.
• If contrast is needed, fasting for 4–6 hours may be recommended.
• Patients with claustrophobia may be offered mild sedation.

During the scan

• The patient lies on their back with the lower spine positioned in the MRI coil.
• Positioning pads are used to maintain stability and comfort.
• Images are acquired in sagittal, axial, and coronal planes to assess lumbar and sacral segments.
• Special sequences may be used to highlight soft tissue, nerves, or inflammation.
• If contrast is required, gadolinium-based agents are injected intravenously.
• The scan typically takes 25–40 minutes.

After the scan

• Patients can resume normal activities immediately unless sedation was given.
• If contrast was administered, fluid intake is encouraged to aid clearance.
• A radiologist analyzes the images and sends a detailed report to the referring physician.

MRI Sequences and Techniques for Lumbo-Sacral Spine

T1-weighted sequences

• Provide excellent anatomical detail of vertebral bodies, discs, and fat-containing structures.

T2-weighted sequences

• Highlight cerebrospinal fluid and detect edema, cysts, or disc pathology.

STIR (Short Tau Inversion Recovery)

• Suppresses fat signals and is highly sensitive for detecting bone marrow edema, infection, and inflammation.

Contrast-enhanced T1 sequences

• Used for tumor detection, infection evaluation, and postoperative scar differentiation.

Diffusion-weighted imaging (DWI)

• Detects certain tumors, infections, and acute ischemic changes.

Common Conditions Diagnosed with MRI of Lumbo-Sacral Spine

Disc herniation

• Protrusion or extrusion of disc material compressing nerve roots, often causing sciatica.

Degenerative disc disease

• Disc dehydration and loss of height leading to chronic back pain.

Spinal stenosis

• Narrowing of the spinal canal leading to nerve compression and leg pain during walking.

Spondylolisthesis

• Forward slippage of one vertebra over another, causing instability and nerve compression.

Tumors

• Detection of benign or malignant lesions affecting vertebrae, nerves, or spinal cord.

Infections

• Osteomyelitis, spondylodiscitis, and epidural abscesses presenting as marrow changes and abnormal enhancement.

Fractures

• Compression or burst fractures, especially in osteoporosis or trauma cases.

Inflammatory conditions

• Ankylosing spondylitis and sacroiliitis involving the sacroiliac joints.

Advantages of MRI of Lumbo-Sacral Spine

• Non-invasive with no radiation exposure.
• Excellent visualization of soft tissues and nerve roots.
• Early detection of disease processes before they appear on X-ray or CT.
• Ability to image in multiple planes for comprehensive assessment.
• Differentiation between scar tissue and recurrent disc herniation in postoperative cases.

Limitations and Considerations

Metallic artifacts

• Implants may distort images and reduce clarity.

Motion artifacts

• Movement during the scan can affect image quality.

Contrast agent risks

• Rare allergic reactions or kidney-related issues; renal function is checked if contrast is used.

Claustrophobia

• May require sedation or an open MRI system.

Patient Preparation Tips

• Wear comfortable, metal-free clothing.
• Remove all metallic accessories before the scan.
• Inform the MRI team about any medical devices or prior surgeries.
• Follow fasting guidelines if contrast is planned.
• Remain still during the scan for optimal image quality.

Conclusion

MRI of the Lumbo-Sacral Spine is a crucial diagnostic tool for evaluating lower back pain, nerve compression, trauma, infections, tumors, and degenerative diseases. With its ability to produce high-resolution images in multiple planes without radiation, MRI offers unparalleled detail of the vertebrae, discs, spinal cord, and surrounding soft tissues. Early detection of abnormalities enables timely and effective treatment, improving patient outcomes and preventing long-term disability. The inclusion of both lumbar and sacral regions in a single scan provides a complete view of lower spine anatomy and pathology, making it an essential imaging study for comprehensive spinal assessment.