Am I Exposed to Radiation During an MRI Scan?

MRIs use magnetic fields and radio waves, not radiation

A patient is loaded into an MRI machine.
A patient is loaded into an MRI machine. Blend Images - ERproductions Ltd/Getty Images

For those of you with multiple sclerosis (MS), MRI scans are a regular occurrence. Most of you probably have one annually, with additional ones ordered if the neurologist suspects a relapse, your symptoms worsen drastically, or if you are participating in a clinical trial of some sort.​

Most certainly, you had at least one MRI when you were in the process of being diagnosed with MS.

With that, it's only natural to wonder whether or not you are exposed to radiation during an MRI scan. The short answer is "no." You're not exposed to any radiation during an MRI (magnetic resonance imaging) scan.

Let's dig a bit deeper, though, into how MRIs work, considering no radiation is used.

Overview of MRI

“MRI” stands for “magnetic resonance imaging,” and it uses magnetic fields and radio waves (not radiation) to produce images. MRI is an extremely important tool used in both diagnosing MS and in monitoring a person's disease course.

During an MRI, extremely strong radio waves (10,000 to 30,000 times stronger than the magnetic pull of the earth) are sent through the body. This temporarily moves the nuclei of the (primarily hydrogen) atoms that make up the body’s cells. When they move back, they emit their own radio waves, which are captured by the scanner. A computer program then translates this data into images, which a radiologist can interpret.

There are two different types of MRIs used in multiple sclerosis, T1-weighted scans and T-2 weighted scans. They work a bit differently to help a neurologist best understand a person's MS.

T1-Weighted Scans

T1-weighted MRI scans provide information about a person's current disease activity, like whether or not they are having an active relapse. For instance, if a person with relapsing-remitting MS is having new neurological symptoms, her doctor may order a T1-weighted MRI scan enhanced with gadolinium (contrast). If inflammation is occurring in the brain, the gadolinium will be able to enter and light up those areas of myelin damage (called MS lesions).

T1-weighted MRI scans also provide information about areas of permanent myelin and nerve fiber damage—these are depicted as "black holes."

T2-Weighted Scans

T2-weighted MRI scans provide information about the total number of lesions (whether new or old). These lesions show up as "bright spots," and give doctors a sense of a person's overall MS burden. Sometimes these lesions clear up and sometimes they progress and develop into black spots (a sign of permanent nerve damage).

MRIs are Essential to MS Care

While it may be strange to think about magnetic fields and radio waves being sent through your body, there is no risk at all to your body’s tissues during an MRI scan.

That being said, if you have any implanted devices that contain metal, they could malfunction or cause a problem. So, it's essential that you inform your technician of the presence of any device, screw, plate or anything else that you have in your body that you were not born with.

The only possible danger from an MRI is a tiny risk of an allergic reaction to gadolinium, the contrast material that is used in people with active MS. The gadolinium can light up areas of active inflammation or loss of myelin in the brain and/or spinal cord.

Also, people with kidney dysfunction are at risk for a more serious condition, called nephrogenic systemic fibrosis, caused by gadolinium.

Putting Medical Radiation in Perspective

While you may worry about radiation from medical tests like CT scans, it may ease your mind to think about this concept—we are surrounded by radiation. Our electronic society, full of computers, cell phones, and televisions, expose us to radiation every day. Consider too that when you fly in a plane coast to coast you absorb the same amount of radiation as you do having your chest x-rayed.

A Word From Verywell

Ultimately, if you are worried about your exposure to radiation, contrast, or anything else during a health-care related test, talk to your doctor. Together you can weigh the benefits and the risks. Usually the former is greater than the latter when discussing MRI, but that is a conclusion that the two of you can come to together.