MRI Use in Multiple Sclerosis

Magnetic resonance imaging is used for diagnosis as well as monitoring

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Magnetic resonance imaging (MRI) is the most widely used methods for diagnosing multiple sclerosis (MS) and for monitoring the progression of the disease. Although completely non-invasive, an MRI provides a detailed look at the central nervous system (CNS)—specifically, the brain, spinal cord, and optic nerve. Without MRI, it would be difficult to detect the effects of MS on the CNS without performing surgery to look directly at these structures.

The technology achieves this by using a large magnet that affects water molecules in the body part being examined; the changes produced translate into images that can be stored in a computer and viewed on a screen or printed on film.

What to expect during an MRI
Illustration by Emily Roberts, Verywell

How MRI Is Used in MS

Multiple sclerosis is characterized by damaged areas in the CNS that result when the body mistakenly attacks the protective layer around nerves in the brain and spinal cord. An MRI makes it possible to see and evaluate these lesions, which is useful for multiple sclerosis in three ways: diagnosis, monitoring, and detection.


When symptoms indicate that a person may have multiple sclerosis, magnetic resonance imaging can be used to help determine if MS is indeed the problem.

MRI is not a failsafe diagnostic test, however: Around 5 percent of people with MS have normal MRIs (no lesions) at the time of diagnosis.

Monitoring the Disease and Evaluating Treatment

MS is a progressive condition. Follow-up MRI testing can help track the development of new lesions and determine if a person's MS is transforming from the relapsing-remitting form of the disease to secondary progressive MS. Many neurologists recommend MS patients have MRIs every year or so.

Regular MRIs also can provide an indication of how well a person is responding to their MS disease-modifying therapy.

Detecting a Relapse

An MRI of the brain and/or spinal cord can determine if new neurological symptoms are being caused by a relapse. This is accomplished by using a contrast material called gadolinium that causes new lesions to "light up" on an MRI (more below).

Types of MRIs

According to the National Multiple Sclerosis Society (NMSS), there are several types of MRI scans for diagnosing and monitoring multiple sclerosis:

T-1 Weighted MRI Without Gadolinium

This type of scan shows hypointense lesions—areas where there's been permanent loss of myelin and/or damage to nerve fibers (axons). This is significant because when myelin and axons are damaged or destroyed, nerve cells cannot communicate with each other effectively or at all, which is what causes a person's unique MS symptoms

Hypointense lesions appear as very dark areas that sometimes are called black holes. The darker the spot, the more damage has occurred. Note that in addition to permanent axonal loss, a black hole or T-1 weighted lesion may represent areas of edema (swelling) that are temporary and disappear on subsequent scans. For this reason, a neurologist often will compare current MRIs with older ones to see if lesions have resolved.

T-1 Weighted MRI With Gadolinium

Gadolinium is a contrast dye that is injected into a vein during and MRI. If gadolinium enters an MS lesion on an MRI, the area will "light up," indicating active MS-related inflammation, or a hyperintense lesion. This means that demyelination has occurred within the last one to two months.

MRI Finding Indication
Areas light up Active inflammation; demyelination occurred within last one to two months
Areas do not light up No active inflammation; lesions likely older than one to two months

T-2 Weighted MRI Without Gadolinium

This type of MRI can reveal overall disease burden, meaning the total number of lesions a person has, both old and new.

Fluid Attenuated Inversion Recovery (FLAIR)

Sometimes spinal fluid interferes with the interpretation of multiple sclerosis activity. A FLAIR MRI reduces this interference.

Spinal Cord Imaging 

Besides providing a picture of how MS might be affecting the spinal cord, this type of imaging can help to diagnose MS by showing that "damage has occurred in different parts of the central nervous system (dissemination in space) at different points in time (dissemination in time)," according to the NMSS.

MRI of the spinal cord is also used to evaluate MS activity when symptoms suggest there's a problem in this structure.

Limitations of MRI

It's important to understand that while magnetic resonance imaging is a key diagnostic and assessment tool for MS, it isn't the only one—nor is it always reliable.

Interpreting an MRI requires skill and careful thought. This is because lesions on MRI do not always perfectly correlate with a person's symptoms. For example, an MRI may reveal lesions that do not cause any symptoms for a person, which are called silent lesions.

Furthermore, small lesions on an MRI may occur naturally as part of the aging process, and so are not necessarily related to a person's disease.

For this reason, ideally, treatment for MS will be shaped based on how a patient feels and is able to function throughout the course of the day. MRI results will play a role, of course, but in most cases should not be the sole dictator of how to manage multiple sclerosis.

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