eMedicine Specialties > Radiology > Brain/Spine

Multiple Sclerosis, Spine: Imaging

Author: Djamil Fertikh, MD, Attending Physician, Division of Radiology, Association of Alexandria Radiologists
Coauthor(s): Michael L Brooks, MD, JD, FCLM, Clinical Associate Professor of Radiology, Drexel University School of Medicine; Adjunct Associate Professor of Radiology, Philadelphia College of Osteopathic Medicine; Director of Neuroradiology, Mercy Diagnostic Imaging
Contributor Information and Disclosures

Updated: May 24, 2008

Computed Tomography

Findings

With the advancement of MRI, evaluation of the spinal cord using axial computed tomography (CT) scanning was abandoned because of its poor sensitivity. Large, masslike lesions can occasionally mimic a neoplasm, and characterizing them can be difficult.

Degree of Confidence

As a result of CT scanning's poor sensitivity, the detection, evaluation, and characterization of MS lesions and enhancement patterns are limited with this modality.

False Positives/Negatives

Primary and secondary neoplasms of the spinal cord (astrocytomas, ependymomas), infection, transverse myelitis, acute infarction, sarcoidosis, and systemic lupus erythematosus may mimic demyelinating MS plaques.

Magnetic Resonance Imaging

Findings

Depending on their age, multiple sclerosis (MS) plaques appear on unenhanced, T1-weighted images as areas of slightly low to low signal intensity. Plaques may appear as nodules, rings, or arcs and generally are less than 2 vertebral bodies in length.⁷ Plaques usually demonstrate prompt enhancement after the administration of a gadolinium-based contrast agent, which most often indicates active disease.⁸ The enhancement may last 2-8 weeks. Steroids typically do not suppress the enhancement of the active plaques. Classic chronic lesions do not demonstrate contrast enhancement.

Most MS plaques appear hyperintense on T2-weighted images. The spinal cord may or may not be focally enlarged. Enlargement of the cord is usually seen with active disease. Larger active lesions may have extensive edema with associated cord expansion. Chronic lesions often demonstrate focal cord atrophy. Spinal lesions usually coexist with more severe concomitant brain plaques. As many as 20% of spinal MS lesions are isolated. Spinal cord narrowing due to atrophic changes is present in 10% of patients with spinal cord involvement.

Tumefacient MS may mimic a neoplasm; a demyelinating process should always be considered if a masslike lesion is encountered. As is the case in the brain, a ring or arc of enhancement can often be found, as opposed to a more nodular or masslike enhancement. Follow-up studies are helpful.

Although not widely implemented, newer methods may be more specific in evaluating MS plaques.⁹ These methods include magnetization transfer and diffusion, as well as proton magnetic resonance spectroscopy (MRS).^10,11

Typically, fast-FLAIR (fluid-attenuated inversion recovery) sequences have been shown to have a lower sensitivity than do fast spin-echo sequences (FSE) for depicting spinal cord MS lesions.^12,13,14

Studies have suggested that more cervical cord MS lesions can be revealed with magnetization transfer–prepared gradient-echo and fast-STIR (short TI inversion recovery) sequences than with FSE sequences, with fast-STIR demonstrating the greatest sensitivity.^{13,15,16,17,18}

Gadolinium-based contrast agents (gadopentetate dimeglumine [Magnevist], gadobenate dimeglumine [MultiHance], gadodiamide [Omniscan], gadoversetamide [OptiMARK], gadoteridol [ProHance]) have been linked to the development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). For more information, see the eMedicine topic Nephrogenic Fibrosing Dermopathy. The disease has occurred in patients with moderate to end-stage renal disease after being given a gadolinium-based contrast agent to enhance MRI or magnetic resonance angiography (MRA) scans.

NSF/NFD is a debilitating and sometimes fatal disease. Characteristics include red or dark patches on the skin; burning, itching, swelling, hardening, and tightening of the skin; yellow spots on the whites of the eyes; joint stiffness with trouble moving or straightening the arms, hands, legs, or feet; pain deep in the hip bones or ribs; and muscle weakness. For more information, see the FDA Public Health Advisory or Medscape.

Degree of Confidence

Although MRI is not specific, it is considered the most sensitive imaging modality for diagnosing spinal cord MS, for evaluating its extent, and for following up the response to treatment. MRI is more sensitive for identifying active plaques than is double-dose CT scanning or clinical examination.

False Positives/Negatives

The main differentials include, but are not limited to, the following:

• Primary or metastatic spinal cord neoplasms (eg, astrocytomas, ependymomas) - The presence of cysts and hemorrhage support the diagnosis of neoplasm.
• ADEM - This may show enhancement. The concomitant presence of brain lesions is the rule. It runs a monophasic course; therefore, it does not have the relapsing course of MS. A history of viral infection within the previous 3-4 weeks should alert the radiologist. ADEM is typically monophasic.
• Sarcoidosis - This involves the CNS in approximately 5% of cases. Concomitant pial involvement is frequently encountered. Enhancement is usually the rule.
• Transverse myelitis - This term is usually used for idiopathic inflammatory myelopathy. Cord swelling and enhancement may be present, often involving a longer segment than MS. MRI of the brain may be helpful for showing additional lesions in case of MS or ADEM. This condition usually responds to steroid therapy; therefore, a treatment trial is often considered before proceeding with biopsy. This process is typically monophasic.
• Infarct - This is more common at the thoracic level. Usually, only a single lesion is present. Contrast may be present, although this is not the dominant feature. Signal alteration usually and initially involves the anterior gray matter (anterior spinal artery distribution). The patient's clinical presentation will be acute. Particularly consider this entity if the patient is older and/or has a history of aortic/vascular surgery.
• Vasculitis - Processes such as systemic lupus erythematosus can result in spinal lesions that mimic MS. Often, multiple lesions are present. However, the clinical history is often known and helps to establish the correct diagnosis.
• Radiation myelitis - Generally, doses higher than 4000 cGy are required to cause this condition. The latency period is 1-3 years. Chemotherapy may be synergistic. Images may show some peripheral enhancement.
• Arteriovenous fistula - Usually, this occurs at the thoracolumbar level, and patients are usually older than 50 years, with a long history of back pain. The cord signal abnormality can involve a very long segment. Look for a serpiginous flow void along the cord surface.

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