Psoriatic Arthritis and Radiology: What You Need to Know

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Psoriatic arthritis (PsA) is a type of inflammatory arthritis that affects some people with the autoimmune skin condition psoriasis. Symptoms of PsA include joint pain, stiffness, and swelling which flare and subside. Treatment for the condition is aimed at reducing inflammation, managing symptoms, and improving quality of life.

PsA can be challenging to diagnose. The most classic signs of the condition—swollen finger joints and pitted fingernails—are not always present, especially early on. There is no specific blood test that confirms PsA. Still, doctors can rely on imaging to ensure an early diagnosis, which is vital since PsA can be aggressive.

This article will discuss how PsA is diagnosed and how radiological imaging aids in diagnosing PsA.

X-ray PsA

SDI Productions / Getty Images

Diagnosis

According to the National Psoriasis Foundation, PsA often starts about 10 years after psoriasis starts, although some people develop PsA first or without psoriasis.

When PsA starts, the most common symptoms are:

  • Swollen, inflamed joints: Especially in the fingers and toes
  • Inflammation of other joints: Including shoulders, knees, and joints of the back and neck
  • Dactylitis: Swelling of fingers and toes that is so severe the digits appear sausage-like
  • Enthesitis: Inflammation of connective tissues where tendons and ligaments attach to bone (the entheses)
  • Synovitis: Inflammation of synovial tissue (the lining of joints)

What Are Synovial Joints?

The synovial joints are movable. They are made up of a fibrous sac-like joint capsule, a synovial cavity containing synovial (lubricating) fluid, and a layer of articular cartilage.

Over time, PsA may cause permanent damage to joints, especially in the smaller joints of the hands and feet. Imaging of fingers and toes can show clear joint deformity from chronic inflammation even early in the disease. An accurate and early diagnosis of PsA is key to preventing this type of joint damage.

In working toward a diagnosis, your doctor will use different diagnostic tools. This includes reviewing symptoms and your medical and family history, a physical exam, lab work, and imaging.

No single test can accurately confirm a diagnosis of PsA, but many can help your doctor get answers. The two most helpful details in confirming a PsA diagnosis are skin and nail changes, and changes seen on radiological imaging.

Radiology Procedures 

If your doctor suspects PsA is the cause of your symptoms, they will want to identify the severity of the condition and the extent of any joint or tissue damage. Imaging can help in determining how far the disease has progressed, what type of damage exists, and treatments that can slow down damaging inflammation.

Your doctor will likely employ different techniques to look for entheses inflammation and joint changes. These include X-rays, ultrasound, magnetic resonance imaging (MRI), computed tomography (CT), and molecular imaging (bone scans).

Not all of these imaging procedures use radiation, but they are all considered to be under the specialty of radiology. The medical doctor who specializes in using and interpreting the images from these procedures is a radiologist.

X-Rays

X-rays are considered the most economical option for assessing and tracking joint damage in PsA. However, they are not always reliable in the early stages of PsA.

Early PsA sometimes causes soft tissue inflammation before any joint or bone changes or damage. This means X-rays won’t show any visible damage to joints and bones.

That is not to say that joint damage can’t occur this early. It can happen, but it may not be visible on X-ray imaging this early.

As PsA progresses, X-rays can show joints and bones are becoming damaged. According to a 2016 report, this may include joint space narrowing and bone erosion (bone loss).

As the disease advances, X-rays may show damage to synovial joints, sacroiliac joints, and entheses. There might also be damage to the small joints of the hands, including the finger joints.

What Are Sacroiliac Joints?

The sacroiliac joints link the pelvis and lower spine. Their main function is to provide stability and reduce pressure on the lower extremities.

Suppose you have a family history of PsA or psoriasis or a personal history of psoriasis, and X-rays don’t show signs of PsA. In that case, your doctor might want to use other types of imaging to help in confirming a diagnosis and determining whether any true damage has started.

This is because studies have found a family history of these conditions can increase the risk for deformity in PsA and other specific disease severity characteristics.

Ultrasound

Diagnostic ultrasound imaging (sonography) uses high-frequency sound waves rather than X-rays to look for changes in bones and tissues in people who have PsA. Some of these changes might be evident in people with psoriasis before PsA symptoms start.

Ultrasounds, especially Doppler ultrasounds, are useful because they are extremely sensitive. They can show inflammation at its earliest phases, synovium thickening and synovitis, early signs of bone erosion, and joint changes in the earliest stages of PsA.

One 2020 report confirms high-frequency sonography (ultrasound) can be a helpful tool for evaluating signs of PsA in the “skin, nail, joints, and entheses.” The report comments on studies that have compared ultrasounds of large entheses (mostly weight-bearing limbs) in people with psoriasis and healthy controls. The majority with psoriasis had pronounced inflammation of the entheses despite not having symptoms.

Magnetic Resonance Imaging 

MRI is one of the most sensitive and specific imaging methods available to your doctor. It uses a strong magnetic field and radio waves rather than radiation (such as in X-rays).

According to a 2021 review, MRI can “visualize peripheral and axial joints and entheses” to aid in assessing inflammation and structural damage linked to PsA. MRI can allow for the detection of erosions, dactylitis, enthesitis, and synovitis long before any of these changes can be found on traditional X-rays.

Unfortunately, most healthcare professionals don’t utilize MRI for PsA because of its costs and lack of availability. Your doctor might consider MRI if they detect inflammation and think X-rays and other imaging have not been helpful.

Computed Tomography

Computed tomography uses multiple X-ray images that are then converted by a computer to form a three-dimensional image.

This isn’t used as frequently as other imaging in diagnosing or assessing PsA, but CT can be an extremely valuable tool for evaluating bone changes in PsA and providing your doctor with further information about the extent and severity of the disease.

CT is especially helpful for evaluating joint areas that are difficult to look at with traditional X-ray, including the shoulder girdle, sacroiliac joints, pelvis, and small joints of the spine.

Bone Scanning

Bone scanning helps access inflammation and how it has affected someone with PsA. For example, whole-body scintigraphy can show the active disease throughout the body, including abnormal bone and joint findings you wouldn’t see on basic X-rays.

This type of imaging isn’t widely used because, even though bone scans are sensitive, they aren’t specific. For example, they can show inflammation throughout the body, but positive findings of inflammation don’t always point to PsA.

Doctors might use bone scanning technology to detect arthritic conditions like PsA, but these tests are more frequently used to reveal bone tumors and bone disorders, as well bone tissue death. Bone scanning might also help assess bone trauma, detect fractures, and determine when they occurred—examining for bone infections and making sense of unexplained bone pain.

Side Effects

Your doctor might request different types of imaging to diagnose and assess PsA. Most types of imaging are non-invasive, which means these tests don’t involve pain or any intrusive methods when used.

But there are risks linked to some of these tests, including exposure to ionizing radiation in tests that use X-rays which can be harmful. Ionizing radiation is a form of energy that removes electrons from atoms, and molecules from things like air, water, and living tissue.

When your doctor recommends an imaging study, they consider the necessity of the procedure and the benefits and risks of the imaging.

According to the Centers for Disease Control and Prevention, some risks from exposure to ionizing radiation might include:

  • A small increase in cancer risk
  • Skin reddening and hair loss after a large exposure
  • Possible allergic reactions related to contrast dye that has been injected into the veins to better see the body parts being looked at

Because these imaging tests are commonly used, the person requesting the test and the person administering the test will take precautions to reduce your exposure to ionizing radiation. According to the Food and Drug Administration, this should include:

  • Checking to see if you have recently had similar testing done
  • Providing background information on the purpose of the test
  • Checking if there is an alternative test that could be done instead
  • Making sure the least number of images are done to reduce radiation exposure
  • Ensuring protective lead shielding to prevent exposure of other body areas to radiation

Special precautions also need to be taken for people who are pregnant and for children.

The risk of an X-ray to a pregnant person and their unborn child tends to be small compared to the benefit of the test being done. However, precautions should be taken to minimize as much risk as possible. Your doctor will consider whether the test can be done later (after the child is born) or if a safer option can replace it.

For children, it is important for radiology professionals to use the lowest exposure settings possible to obtain a good image. The requesting healthcare professional will proceed if they believe the benefit outweighs the risk.

They will also determine if they can use alternative imaging methods, such as ultrasound or MRI. Ultrasound and MRI imaging do not involve ionizing radiation exposure.

Treatment

The goal of treating PsA is to reduce pain and other symptoms, and to prevent joint damage. Most people with PsA will take medicines regularly to keep inflammation, pain, and swelling under control. Some of these medicines can help manage both PsA and psoriasis.

Medicines used to treat PsA include nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroids, disease-modifying antirheumatic drugs (DMARDs), and biologics.

  • NSAIDs: NSAIDs, including ibuprofen and naproxen, help reduce joint pain and swelling. These medicines relieve symptoms of PsA, but they do not affect the biological or inflammatory processes of the condition.
  • Corticosteroids: If you have a PsA flare-up, your doctor may prescribe a short course of oral corticosteroids or give you a steroid injection. These drugs reduce inflammation, lessening pain and swelling. They are given for a short term because they have harsh side effects, including worsening of skin symptoms and a higher risk of serious infections.
  • DMARDs: DMARDs work by affecting the entire immune system. Commonly prescribed DMARDs for PsA are methotrexate, sulfasalazine, and leflunomide. They are either given alone or in combination to slow or stop PsA from progressing.
  • Biologics: This type of DMARD prevents specific proteins from promoting inflammatory processes that lead to PsA symptoms. Biologics reduce inflammation and slow the disease process. They are given either by injection or infusion, and may be given on their own or with methotrexate. Biologics to treat PsA include Humira, Cosentyx, Taltz, and Stelara.

Additional Treatments

Your doctor will also recommend changing some everyday habits to manage the effects of PsA. Some people find making changes like eating a healthy diet, being active, and reducing stress can help reduce pain and even the need for some medicines. 

Physical and occupational therapies can also help manage PsA. A therapist can create a plan to help you manage pain and other PsA symptoms, and better cope with existing joint issues.

If joint damage is severe and the pain and loss of movement affect your qualify of life, your doctor may recommend surgery. Different surgical options are available to repair or replace damaged parts of a joint.

Fortunately, most people with PsA can manage symptoms without surgery and will never need surgery.

Monitoring

Imaging studies can help to determine whether treatments are working. MRI is the most effective monitoring option, but X-rays and ultrasound are also helpful.

If your doctor requests imaging that shows no joint changes or damage, they might decide your current treatment plan is working and continue using those methods. However, if imaging starts to show bone and joint changes or persistent inflammation, your doctor may want to add treatments or modify your current treatment plan.

Summary

Psoriatic arthritis is diagnosed using radiological imaging. Doctors commonly use X-ray, ultrasound, and MRI to aid in the diagnosis of the condition, and if needed, they will employ other imaging techniques, including CT and bone scans.

MRI tends to be a more expensive method, but it is one of the most sensitive ones and can help find damage long before PsA symptoms begin.

Ultrasound can be very helpful in examining changes to bones and tissues. It is also cost effective and causes little risk because of the lack of radiation. X-rays aren’t as useful early on in PsA, but they can be relied on as PsA advances.

Imaging is also key in assessing and monitoring the inflammatory effects of the condition and if treatments are working. MRI is the most accurate method for monitoring disease progression.

A Word From Verywell

The best way to prevent joint and tissue damage in PsA is to stop inflammation. Your PsA treatments are the most effective way to achieve this goal. Be sure you follow all of your doctor’s instructions and take all of your medicines as prescribed.

Most of the medicines for treating PsA are meant to be taken long term. That means even if you are feeling better, you shouldn’t stop taking your medications. Be sure to keep up with regular doctor’s appointments and let your doctor know if you continue to have pain and flare-ups. 

Frequently Asked Questions

  • What does psoriatic arthritis radiology look like on X-rays?

    Characteristics of PsA on radiologic imaging might include joint erosions, joint space narrowing, and bony spurs. Imaging might also show other deformities, including a pencil-in-cup deformity and a telescoping appearance, which, while rare, can be seen in the hands and feet of a person with severe PsA.

    Other joint damage that imaging can detect includes abnormalities to the finger joints and the entheses, and bony growths to the spine and sacroiliac joints. Imaging studies can also show signs of dactylitis, enthesitis, and synovitis long before a person feels pain and other PsA symptoms.

  • What are the first signs of psoriatic arthritis? 

    Psoriatic arthritis typically starts many years after the onset of psoriasis, but some people may develop joint pain before they notice skin symptoms. One of the earliest symptoms of PsA is morning stiffness or stiffness after sitting for long periods of time.

    At this early stage, PsA causes stiffness and pain in one or more joints, usually the fingers and toes, but it can affect large joints as well. PsA can also cause pain and swelling in the tendons and surrounding tissues that connect to bone.

    Additional early signs of PsA include pitted nails, nail bed separation, low back pain, swollen fingers or toes, foot or hand pain, and severe fatigue.

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13 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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