Does Axial Spondyloarthritis Show Up on an MRI?

Axial spondyloarthritis (axSpA) is a type of inflammatory arthritis affecting the spine and sacroiliac (SI) joints linking the pelvis to the spine. The condition primarily causes back pain and stiffness, but because back pain is a symptom of numerous conditions, an axSpA diagnosis can take many years. 

Magnetic resonance imaging (MRI) can find active inflammation early to aid in an axSpA diagnosis and monitor for structural changes that lead to spine fusion. Unfortunately, MRI is not always the first imaging choice, and not all medical providers recognize early bone and joint changes in axSpA.  

This article covers how axSpA is diagnosed, challenges in diagnosis, the benefits of MRI for diagnosis and monitoring, and more. 

Diagnosing Axial Spondyloarthritis

There are two subsets of axSpA—non-radiographic axSpA (nr-axSpA) and ankylosing spondylitis (AS). Nr-axSpA causes inflammation of the spine and other joints throughout the body, but there is radiographic (X-ray) evidence of joint or bone damage.

AS will cause inflammation that will lead to bone and joint damage, and that damage will be evident on X-rays and MRIs of the spine. Nr-axSpA is sometimes a precursor to AS.

The symptoms of axSpA usually start in late adolescence or early adulthood. AxSpA can also occur in children and middle-aged adults, with most people being diagnosed by age 45.

The disease is more common in families. For example, your risk for axSpA increases if you have a first-degree relative (parent, sibling, or child) with the condition. The presence of a genetic marker called human leukocyte antigen B27 (HLA-B27) also increases the risk of developing axSpA. HLA-B27 is believed to run in families.

Testing Methods

AxSpA can be a challenging diagnosis to make. No single test can confirm the condition. Instead, a healthcare provider will rely on your medical and family histories, a physical exam, blood work, and imaging tests to confirm a diagnosis. 

Medical and Family History  

The first step in determining whether a person has axSpA is to review their medical and family history.  Back pain in axSpA is inflammatory rather than mechanical.

Mechanical back pain results from various events, such as heavy and improper lifting, injury, or uncomfortable sleep posture. In contrast, inflammatory back is persistent, lasts three or more months, worsens with inactivity, and improves with nonsteroidal anti-inflammatory drugs (NSAIDs) and movement.

Additional symptoms of axSpA are:

• Pain in the buttocks and hips
• Peripheral joint pain in the large joints of the arms and legs
• Fatigue
• Fever
• Appetite loss 
• Enthesitis (inflammation of the entheses—the areas where ligaments and tendons that to bone)
• Eye inflammation
• Psoriasis (an inflammatory skin condition that causes skin cell overgrowth)

Researchers believe the HLA-B27 gene is inherited. Let your healthcare provider know if axial spondylitis or other autoimmune diseases run in your family.

Physical Examination 

The physical exam for axial spondyloarthritis looks for physical and neurological symptoms. 

For the physical examination, the healthcare provider will want you to bend your back and pelvis in different directions to check for pain and stiffness and see if your range of motion has been affected.

They will also push on some body areas, mainly the entheses, to look for tender spots. Common areas affected by enthesitis are where the ribs meet the breastbone, the back and underparts of the heel; areas of the spine closest to the skin; and at the back of the head where the spine meets the neck.

Severe axSpA can lead to breathing troubles, especially in AS. These result from lung scarring caused by chronic inflammation, chest wall stiffening, and the upper body arching forward from damage to the spine. 

For the neurological exam, the healthcare provider will want to assess sensory and motor function, reflexes, and muscle strength. They will also want to know if you are experiencing neurological symptoms, such as nerve pain, numbness, muscle spasms, and bowel and bladder dysfunction.

Neurological symptoms are more common in long-standing axSpA but might affect some people early in the disease process.

Blood Work 

Blood work for diagnosing axSpA includes inflammatory marker testing, blood tests to rule out other conditions, and genetic testing to see if you carry the HLA-B27 gene. While blood work alone cannot confirm axSpA, it can help the healthcare provider make sense of your symptoms.

The healthcare provider may request the following blood work if they suspect axSpA:

• Erythrocyte sedimentation rate (ESR or sed rate): This test looks for inflammation in the body. 
• C-reactive protein (CRP): CRP is a protein that the liver makes, and high levels could mean a condition that causes chronic inflammation. 
• Complete blood count (CBC): This test checks red and white blood cell counts. Low red blood cell counts and high white blood cell counts indicate a condition that causes inflammation. 
• Rheumatoid factor (RF): This test is often done to rule out other autoimmune diseases, such as rheumatoid arthritis and lupus. 
• HLA-B27 blood test: HLA proteins typically help the body's immune system distinguish between healthy cells and foreign, harmful ones. HLA-B27 is a mutated gene associated with autoimmune diseases affecting the spine.

Imaging 

Different imaging studies can help a healthcare provider make a diagnosis of axSPA, including conventional radiology (X-rays), MRI, computed tomography (CT), and ultrasound.

X-rays are generally the standard for diagnosing axial spondyloarthritis, but MRI, CT, and ultrasound might be more reliable for evaluating joints and soft tissues in the spine.

A healthcare provider might also rely on X-rays and MRIs to track disease progression or to look for structural changes in the spine and SI joints. 

Challenges of Diagnosing AxSpA

AxSpA can be a challenge to diagnose because the condition develops slowly. Symptoms of axSpA might resemble those of other spondyloarthritis conditions, including psoriatic arthritis. Also, no single test can help a healthcare provider confirm the cause of your symptoms.

A 2021 Rheumatology review of studies found the average diagnostic delay for axSpA was 6.7 years. These delays appeared to be prevalent worldwide and occurred in both high-income and middle-income countries.

Factors linked to these delays included individual factors (low education levels, younger age at the start of symptoms, and absence of non-joint symptoms) and disease presentation. 

MRI vs. X-Ray: Which Is Better?

An MRI takes multiple images across different body areas with the help of a magnetic field and computer-generated radio waves to create images of tissues throughout the body.

An X-ray produces a single flat image using ionizing radiation. For multiple images, the X-ray technician must set the machine to change positions for different angles and body areas.

Imaging studies are crucial to diagnosing axSpA. Inflammation in axSpA might eventually damage the spine and SI joints. X-rays can check for joint and bone changes, but early signs cannot be seen on X-rays. To look for early radiographic signs, MRI might be more reliable.

An MRI can offer more detailed images of bones and soft tissues and reveal evidence of axSpA earlier in the disease process.

How Does an MRI Work?

An MRI machine is a large, tube-shaped machine that creates a magnetic field that transmits radio waves from the scanner to produce weak signals that create cross-sectional images. Images are often three-dimensional (3D). 

MRI is non-invasive but can produce detailed images of nearly every internal body structure. No radiation is produced during the MRI. In contrast, X-rays use ionizing radiation to produce images. MRI scans can provide your healthcare provider with details to diagnose a condition, plan its treatment, and monitor it.

If you have axSpA, your healthcare provider might request an MRI to look for active inflammation of the spine and SI joints, new bone formation in the spine or SI joints, erosive bone damage, disc problems (especially at the lower spine), and fusing of the facet joints.

Erosive bone damage refers to bone loss from a disease process. The facet joints are located at the top and bottom of each vertebra (each small bone of the spinal column). They connect the vertebrae (all the bones of the spinal column) and allow for spinal movement.

Radiographic signs of axSpA, such as active inflammation and new bone formation, can be found early on MRIs, and MRIs can be helpful in the diagnosis process. MRI can also track disease progression and help your healthcare provider catch problems early when treatment plan changes are more helpful.

What to Expect When Getting an MRI

You will be placed inside a large magnetic tube to obtain MRI scans. You must remain still during the imaging process to avoid blurring the images. You might be given intravenous (IV, within a vein) contrast before or during the MRI to help body protons align with the magnetic field. The faster the alignment, the better the imaging. 

Side effects after an MRI are rare, although some people could experience a reaction to the contrast dye. If you experience a reaction to the dye, such as itching, swelling, or breathing troubles, reach your healthcare provider immediately.

If you feel the symptoms of the reaction might be life-threatening or severe, call 911 or head to your local emergency room. You should also inform your healthcare provider if you notice any pain, redness, or swelling at the IV site that continues after you get home. 

If you are concerned about changes to your spine or other joint damage from axSpA, ask your healthcare provider about getting an MRI. Because MRI procedures are expensive, you should check with your insurance company to see what they cover and what your out-of-pocket costs might be. 

Summary 

Axial spondyloarthritis is a lifelong progressive disease that gets worse with time. It is diagnosed based on medical and family history, physical examination, blood work, and imaging. Imaging is the most helpful tool for diagnosing the condition. 

Diagnostic imaging tools used in axSpA include X-rays, CTs, ultrasounds, and MRIs. MRI scans can detect active inflammation and bone formation very early in the process. MRI can also monitor the progression of axSpa in the spine and SI joints and look for fusing or facet joint and disc problems. 

A Word From Verywell 

Axial spondyloarthritis is a progressive disease you will need to live with for the rest of your life. While there is no cure, it is treatable and manageable.

For most people, living with axSpA means having periods of flare-ups (increased symptoms) and remission (little or no symptoms). For others, it could mean a severe disease that leads to spinal fusion, joint damage, breathing troubles, and neurological problems.

It is vital to see a rheumatologist (a doctor specializing in arthritis conditions) who can help you manage axSpA and to follow your treatment plan. This is the best way to improve your outlook and keep you moving and enjoying life.