Multiple Sclerosis (MS) is a chronic neurological autoimmune condition affecting millions, disrupting information flow in the brain and body and causing physical and cognitive challenges. Advanced diagnostic imaging, like MRI, helps clinicians visualize subtle changes for accurate diagnosis and management.
What is Multiple Sclerosis and Why Scan the Spine?
Multiple Sclerosis is an autoimmune disease where the body’s immune system attacks the myelin sheath insulating nerve fibers in the central nervous system (CNS). This damages the myelin, or demyelination, disrupting electrical signals along nerves. Damaged areas, called lesions or plaques, can form in the brain, spinal cord, and optic nerves, causing diverse symptoms.
The spinal cord is a common site for MS activity and lesion formation. Lesions here can lead to symptoms like walking difficulties, numbness, tingling, limb weakness, and bladder or bowel problems. Identifying these lesions helps understand the disease’s extent and its impact on physical functions.
Magnetic Resonance Imaging (MRI) is the preferred imaging technique for diagnosing and monitoring Multiple Sclerosis. MRI uses magnetic fields and radio waves to image soft tissues, including the brain and spinal cord. Unlike X-rays, MRI does not use ionizing radiation, making it safe for long-term monitoring. Its ability to visualize subtle demyelination in the spinal cord makes it an indispensable tool for MS.
Preparing For and Undergoing a Spinal MRI
Preparation for a spinal MRI ensures patient safety and image quality. Patients must remove all metal objects, including jewelry and clothing with metal fasteners, as metal interferes with the scanner’s magnetic field. Fasting may be recommended if a contrast agent is planned.
During the procedure, the patient lies on a movable table that slides into a tube-shaped scanner. The machine is noisy, so earplugs or headphones are provided. Remaining still throughout the 30-60 minute scan is important for clear images. Patients with claustrophobia should discuss this with staff, as open MRI machines or mild sedatives may be options.
A gadolinium-based contrast agent is often administered intravenously during a spinal MRI for MS. It highlights areas where the blood-brain barrier is disrupted, indicating active inflammation and new lesions. Gadolinium makes active lesions appear brighter, helping radiologists differentiate them from older ones. The contrast agent is safe, though some may experience a cool sensation or metallic taste.
Safety is important due to the MRI’s powerful magnetic field. Patients with implanted medical devices like pacemakers, defibrillators, or metal clips may not be able to undergo an MRI. Disclose all medical implants and any metal in the body, including shrapnel, to the medical team before the scan. This allows healthcare providers to assess risks and determine if MRI is safe.
Deciphering Spinal MRI Results
Radiologists analyzing a spinal MRI for Multiple Sclerosis look for lesions indicating demyelination and inflammation. T2 hyperintense lesions, appearing as bright white spots on MRI sequences, are a common finding. These lesions represent increased water content from inflammation, demyelination, or axonal loss, indicating MS activity and are key for diagnosis.
T1 hypointense lesions, or “black holes,” appear as dark areas on T1-weighted MRI sequences. These suggest severe or chronic tissue damage, possibly indicating irreversible axonal loss or significant demyelination. Their appearance can vary, with some being transient and others persisting, reflecting different stages of damage.
Enhancing lesions indicate active inflammation and blood-brain barrier breakdown. They appear bright after intravenous gadolinium contrast. An enhancing lesion signifies a new or active area of demyelination, evidence of disease activity at the time of scan. Their presence strongly indicates recent disease activity and guides treatment decisions.
Spinal cord MS lesions often appear ovoid or round, located on the posterior or lateral aspects. They are smaller than brain lesions, typically less than two vertebral segments, and found in the cervical or thoracic regions. Their presence, with lesions in other characteristic locations like the brain or optic nerves, contributes to the “dissemination in space” criterion for an MS diagnosis.
MS diagnosis uses criteria like the McDonald Criteria. These require “dissemination in space” (lesions in at least two CNS areas) and “dissemination in time” (new lesions on follow-up scans or both enhancing and non-enhancing lesions on an initial scan). Lesion characteristics and distribution on spinal MRI, combined with clinical symptoms, help establish a definitive MS diagnosis.
The Role of Spinal MRI in MS Management
Beyond initial diagnosis, spinal MRIs monitor MS progression. Regular follow-up scans track new, enlarging, or enhancing lesions, signaling disease activity. This visualization provides objective evidence of disease evolution, even if clinical symptoms remain stable.
Follow-up scans assess the effectiveness of disease-modifying therapies (DMTs) for MS. A reduction in new or enhancing lesions, or stabilization of existing ones, indicates successful treatment in slowing inflammatory activity. Increased lesion activity despite treatment may suggest adjusting therapy or exploring alternatives.
The frequency of follow-up spinal MRIs varies by patient circumstances, disease activity, and treatment. Initially, scans may be more frequent (annually or every two years) to establish a baseline and monitor early treatment response. If new or worsening clinical symptoms emerge, an earlier scan may be performed to investigate new disease activity.
MRI findings, combined with clinical symptoms and neurological examination, guide treatment decisions and provide prognostic insights. Significant spinal cord lesion burden, for instance, may indicate a higher risk for physical disabilities, influencing therapy and rehabilitation. This comprehensive picture helps tailor a personalized management plan for individuals with MS.
References
National Institute of Neurological Disorders and Stroke. Multiple Sclerosis. Available at: https://www.ninds.nih.gov/health-information/disorders/multiple-sclerosis
Multiple Sclerosis Association of America. About MS. Available at: https://mymsaa.org/about-ms/
Mayo Clinic. MRI. Available at: https://www.mayoclinic.org/tests-procedures/mri/about/pac-20384803
RadiologyInfo.org. MRI of the Spine. Available at: https://www.radiologyinfo.org/en/info/mri-spine
American College of Radiology. MRI Safety. Available at: https://www.acr.org/Practice-Management-Resources/ACR-Manuals/MRI-Safety-Manual
National Multiple Sclerosis Society. MRI. Available at: https://www.nationalmssociety.org/Symptoms-Diagnosis/Diagnosis/MRI
FDA. MRI (Magnetic Resonance Imaging) Safety. Available at: https://www.fda.gov/radiation-emitting-products/magnetic-resonance-imaging-mri/mri-magnetic-resonance-imaging-safety
National Multiple Sclerosis Society. Understanding MRI in MS. Available at: https://www.nationalmssociety.org/What-You-Can-Do/Take-Action/Understanding-MRI-in-MS
American Academy of Neurology. MRI in MS Diagnosis and Monitoring. Available at: https://www.aan.com/
Polman, C. H., Reingold, S. C., Banwell, S., et al. (2011). Diagnostic criteria for multiple sclerosis: 2010 revisions to the McDonald criteria. Annals of Neurology, 69(2), 292-302.
National Multiple Sclerosis Society. Monitoring MS. Available at: https://www.nationalmssociety.org/Treating-MS/Monitoring-MS
O’Connor, P. W., & Freedman, M. S. (2014). The role of MRI in the diagnosis and monitoring of multiple sclerosis. Current Opinion in Neurology, 27(3), 263-270.