Ankylosing spondylitis (AS) is an autoimmune disease that causes inflammation in the joints of your spine and spots where tendons and ligaments attach to bone.

Common symptoms include lower back pain, stiffness, and fatigue. In severe cases, inflammation can cause vertebrae to fuse together, which is known as bamboo spine.

It can take years for changes in your bones due to ankylosing spondylitis to show up in X-rays. But in some cases, magnetic resonance imaging (MRI) scans can catch signs of inflammation earlier.

We’ll go over when an MRI is used to detect or monitor ankylosing spondylitis and what the procedure is like.

Unlike X-rays, MRIs are able to capture inflammatory changes in bone and soft tissues. This makes MRI the best imaging test doctors have to recognize early spine and sacroiliac joint (SI joint) changes in ankylosing spondylitis.

X-ray has been used by healthcare professionals to diagnose ankylosing spondylitis because it shows the skeletal structure clearly and can capture skeletal trauma and alignment, according to 2012 research.

However, by the time AS shows up on X-rays, it has often gone untreated for years. It can take up to a decade for the disease to present on an X-ray, according to 2015 research.

Learn more about how X-rays are used to help diagnose and monitor AS.

There are no set criteria for MRI evaluation for ankylosing spondylitis, and specificity and sensitivity are still limited. MRI should not be used as the only evaluation tool for AS since it does not capture the full range of clinical findings, according to 2018 research.

Also, ankylosing spondylitis may be present but not show up on an MRI.

Delay in diagnosis is an ongoing problem in ankylosing spondylitis.

A 2015 study of over 160 participants with AS found the average time between symptom onset and diagnosis was around 8 years, with some patients waiting more than 10 years. Other studies often cite a diagnostic delay of 7 to 10 years.

During this delay, people with ankylosing spondylitis often have to manage chronic pain without answers or effective treatment. MRI’s sensitivity to soft tissue makes it a key diagnostic tool in the earlier stages of ankylosing spondylitis.

The sooner you can rule ankylosing spondylitis in or out, the sooner you can start treatment.

Magnetic resonance imaging (MRI) is a noninvasive imaging technology. It produces three-dimensional images by using very strong magnetic fields and radio waves.

MRIs have been in use since the 1980s and are considered safe as long as technicians and patients follow directions. Unlike with X-rays, there is no radiation involved in an MRI.

MRIs are especially useful for seeing soft tissues in addition to bones. Structures like the brain, spinal cord, nerves, muscles, and tendons are all visible with an MRI.

The MRI machine may be open or closed, though not every facility has open MRIs. If your doctor has ordered an MRI, they may direct you to another part of their clinic or a special radiology center to get your imaging done.

The position you are in during an MRI depends on the area of your body being examined. Sometimes your entire body will be fully inside the MRI machine. You usually have to stay very still while the MRI works.

While MRIs are considered very safe, they are not the best option for everyone. Some people shouldn’t get an MRI or should do so with caution.

The MRI’s magnets can impact certain medical devices and implants, according to the National Institute of Biomedical Imaging and Bioengineering. These include:

If one of these applies to you, your doctor will not typically recommend an MRI.

MRI is also not recommended for:

  • people in their first trimester of pregnancy
  • people with claustrophobia (fear of enclosed spaces)
  • people with certain types of chronic pain (may affect your ability to stay in one position)

In rare cases, MRIs are known to affect the ink in tattoos, according to 2019 research. This may cause a warm, tingling, or even burning sensation in the tattoo during an MRI.

While researchers have found this reaction very uncommon, it’s important you inform your doctor and technician of any new tattoos. Let them know if you are experiencing any symptoms related to a tattoo while in the MRI machine, as you may have to stop the imaging process.

Getting an MRI has the potential to be stressful. It might help to remember that MRI is a very common type of imaging that millions of people get every year. While MRIs can be uncomfortable, they can also provide vital information about your health.

Here’s an overview of what to expect during an MRI. Knowing the stages of the imaging process may help reduce anxiety and stress.

Don’t hesitate to ask your doctor or technician if you have a concern about your MRI. They can weigh any risk factors you have against the possible benefits of an MRI. If you decide an MRI isn’t your best option, your doctor can help you find a next step that works for you.


Depending on the type of MRI, your doctor may tell you not to eat or drink beforehand for a certain amount of time.

You’ll be asked to take off all your jewelry and turn over any metal objects, like glasses or car keys, since these things can be affected by the magnets. You will then change into a gown to wear during the procedure. A locker is provided to store your clothes and belongings.

Contrast agents

Some MRIs are done with contrast. Contrast agents work similarly to dyes, making tissue structures and changes sharper and more visible to the MRI machine. Contrast agents can be injected locally, after a numbing agent, or infused systemically before your procedure.

The use of contrast is not recommended for everyone. People with kidney disease or known renal failure likely shouldn’t receive contrast.

MRIs evaluating ankylosing spondylitis are ordered both with and without contrast.


A radiology technician will help set you up in the MRI machine and monitor you and the machine from a nearby room.

You will usually have an earpiece and button you can use to communicate with the technician if you have any questions or concerns. The technician may update you throughout the imaging process, letting you know how much time is left or if you need to move slightly.

The technician will help position you on a sliding table and roll you into an enclosed tube, although some centers have open MRIs. You’ll be asked to lie very still so the images don’t come out blurry.

When getting an MRI as part of being evaluated for ankylosing spondylitis, you will typically be positioned flat on your back.


The amount of time you spend in the MRI machine varies greatly depending on the area of your body being imaged and the type of MRI. It ranges from around 15 to 90 minutes.

For ankylosing spondylitis, an MRI typically lasts 30 minutes, according to 2007 research. This is the time actually spent in the machine and doesn’t include the check-in and prep.


The magnets used to make MRI images are quite loud. You’ll be given earplugs or, in some cases, headphones with music. Some people find the noise of an MRI very distressing and the most difficult part of the procedure.

Here’s a video demonstrating the many different sounds an MRI machine makes.

Because of the loud noises, the enclosed nature of most MRIs, and the fact that you have to stay still, some people feel claustrophobic and anxious. Try to focus on your breathing and remember the MRI process is temporary.


Your healthcare team will call you with the results or schedule you for a follow-up visit to review them.

Doctors who review X-ray, MRI, or CT scan results are called radiologists. They’re trained to look for tiny differences that the average person wouldn’t notice. A radiologist will write a report of your MRI for your doctor to review along with the images.

If your doctor identifies signs of ankylosing spondylitis on your MRI, they may make an official diagnosis and begin working with you to develop a treatment plan.

It’s important to remember that an MRI cannot rule out ankylosing spondylitis completely. It’s possible to have AS and a seemingly regular MRI, especially early on in the disease.

MRI is one of several tools used to evaluate someone for ankylosing spondylitis.

In addition to conducting a physical exam and listening to your symptoms, doctors may use:

  • Lab tests. There is no single blood test that can specifically identify AS, but doctors usually look for a helpful biomarker called HLA-B27, which is present in around 90 percent of people with AS. However, this marker is also common in the general population, and most people with it will never develop the disease.
  • Other imaging. This includes both X-rays and CT scans.

MRIs can be very helpful in looking at soft tissues, joints, tendons, and ligaments. In evaluating ankylosing spondylitis, MRIs can be more sensitive than X-rays and show signs of inflammation earlier in disease progression.

Getting an MRI is stressful to some people, as it involves loud noises and usually being in an enclosed space. Some MRIs are done with contrast, which requires injection.

Make sure you communicate openly with your doctor and technician before and during this imaging process. Consider bringing along a friend or family member for support.

Ultimately, there is no single diagnostic test for ankylosing spondylitis, but an MRI scan can help provide more information. It’s possible to have AS and regular MRI results.

MRIs aren’t recommended for people with certain medical devices or implants that could interact with the machine’s strong magnets. Talk with your doctor about risk factors and other diagnostic tools that might be a better fit.