axSpA imaging tests


Axial spondyloarthritis (axSpA) imaging tests are used to look for signs of axSpA and to monitor the disease’s progression. These tests primarily look for bone damage in your joints caused by the inflammation associated with axSpA.

X-rays used to be the most common form of imaging test used by doctors, but they weren’t very helpful for reaching an early diagnosis. Today there are more advanced imaging tests, like MRIs and ultrasounds, which allow doctors to find early signs of axSpA like soft tissue inflammation. Along with imaging tests, your doctor will perform a range of tests, including blood tests to help reach a diagnosis of axSpA. You will also undergo a physical examination for other signs and symptoms of axSpA that cannot be detected from an imaging test.

What are Imaging Tests?

Imaging tests are performed on patients to help identify signs and progression of axSpA. These tests essentially look inside your body so that doctors can see if joint damage has occurred. Imaging tests play a role in diagnosing axSpA and monitoring your disease over time. Imaging tests provide doctors with a picture of your disease status so that they can make decisions about the best course of treatment.

What do Imaging Tests Look for?

axSpA imaging tests look for signs of bone erosion (loss of bone in the joint), inflammation and swelling, tissue damage and overall joint deterioration. 

Imaging tests can show where damage to the joint is occurring. Bone erosion is a very serious concern as it can be irreversible. Imaging tests identify this early on so that targeted treatment can begin and attempt to prevent further damage to the joint.

If imaging tests do not find signs of bone deterioration, it doesn’t entirely rule out a axSpA diagnosis. It could mean instead that the disease is in its early stages and hasn’t yet produced any permanent bone damage.

Imaging tests ultimately provide an opportunity to treat axSpA symptoms as soon as possible. Treatment is far more effective in reducing pain, stiffness, swelling and bone erosion when started in the early stages of the disease.

Types of Imaging Tests

There are four main types of imaging tests used in diagnosing and monitoring disease. These are:

  • X-ray
  • Computerized axial tomography (CAT) scan
  • Magnetic Resonance Imaging (MRI)
  • Ultrasound

Doctors may use one or a combination of all tests to help reach a diagnosis and monitor progression.


X-rays are tests that allow doctors to see the bones and joints, to find where bone erosion may be occurring. Multiple x-rays taken over time can also show doctors how quickly any joint damage is progressing.

X-rays are the standard imaging test doctors use to assess joint damage in axSpA patients. Though x-rays are a preferred method of imaging test, they aren’t very useful for detecting the earliest signs of axSpA. This is because they only reveal damage after it has been done, meaning the symptoms have progressed to the point of causing noticeable (and usually permanent) damage. You may find that your doctor will take X-rays alongside other imaging tests.

Computerized axial tomography (CAT) scan

Also called a computed tomography (or CT) scan, this is non-invasive test combines X-ray equipment with sophisticated computers to record two-dimensional slice images of your body and, in some cases, turning those slices into a three-dimensional view of the back. CT scan shows soft tissues such as ligaments and muscles more clearly than traditional X-rays do, so it is more useful for diagnosing certain problems, such as ruptured or degenerated discs, spinal stenosis, tumors or infections of the spinal cord.


The MRI test is a more advanced test which involves a detailed look into the patient’s body.  Whereas X-rays mostly just look at bones, MRIs can detect abnormalities in the soft tissues like muscles, tendons and joint capsules.

MRIs are better at detecting early signs of axSpA than X-rays. MRIs can reveal the active inflammation occurring in the joint capsule or early signs of bone inflammation, prior to any permanent damage occurring.

One early sign of bone deterioration is the build-up of fluid in the bone marrow. MRIs are able to detect these areas of fluid build-up, helping predict areas of future bone erosion.


Ultrasounds are a newer technique used in diagnosing and monitoring axSpA. This form of test uses high-frequency sound waves to produce pictures of the inside of the patient’s body. Unlike x-rays, ultrasounds do not emit any radiation.

Like MRIs, ultrasounds are better at detecting early signs of joint inflammation and bone erosion caused by axSpA compared to x-rays, which can help support a axSpA diagnosis.

Ultrasounds are also useful in detecting disease progression. For example, if you show signs of remission, your treatments might be adjusted. But an ultrasound might show that there is still inflammation present and requiring further treatment.

The use of ultrasound in monitoring joint deterioration  is becoming increasingly common.

How Imaging Tests help diagnose axSpA

None of the imaging tests on their own can reliably diagnose axSpA. axSpA is a clinical diagnosis, meaning that results from imaging tests is used by your doctor in combination with the assessment of physical symptoms, blood tests, and medical history to diagnose axSpA.

Imaging tests are helpful tools for diagnosis and providing a clear medical picture of your present condition. Imaging tests are also used post-diagnosis to continue to monitor your level of bone erosion. Imaging tests can indicate the severity and speed of the disease’s progression.

Imaging Testing to predict axSpA outcomes

All four imaging tests can be used to keep track of how axSpA progresses over time. However, the tests do not allow doctors to predict your clinical outcome as each case of axSpA is different.

Beyond using x-rays and other axSpA imaging tests to carefully check for additional joint damage, doctors cannot predict if joint damage will worsen or slow down.

Does Medicare cover the cost?

Medicare does cover the cost of some imaging tests, but not at all. Each provider sets their own fee. Some providers do bulk bill, so you don’t have to pay anything. Sometimes you can claim back part of the fee, but you may still be left out of pocket. You should discuss with your doctor or service provider about the cost of imaging tests and whether Medicare will cover some or all of the cost. It is important to keep in mind that wait times for an imaging test may vary depending on the service provider. For example, a public health provider may take longer to book an appointment compared to a private provider, however the cost may be considerably different.

If you have private health insurance, you may be covered for imaging tests while you are in hospital. However, private health insurance may not cover imaging tests that are done outside of a hospital and not covered by the MBS.

It is important to discuss your options with your doctor or service provider and ensure you have all the relevant information. Some questions that may be helpful to ask the provider, are:

  • Will there be any out-of-pocket expenses to you?
  • Is there a payment plan available?
  • Do they have a way to support you if you are on a low income or if the cost will cause you financial stress?
  • Will there be any additional costs, over and above the cost of the test?
  • How much will travel and parking cost?

If you or someone in your family needs a lot of tests, you may be eligible for Medicare Safety Net. This means you can get a higher rebate from Medicare for imaging tests and other medical services.

For more information visit HealthDirect or speak with your doctor.



This resource has been developed based on the best available evidence. A full list of references is available upon request.