Radiology, such as X-ray imaging, can help doctors detect specific structural changes to your joints that may indicate psoriatic arthritis (PsA). They may also use other imaging, such as MRI, to detect inflammation.
Imaging, including radiology, plays an important role in allowing doctors to diagnose PsA and distinguish it from other joint conditions. It can also help doctors see the extent of your joint damage and track how the disease progresses.
Doctors often use X-rays as the first type of imaging to diagnose PsA, but you may also receive:
- ultrasound
- MRI
- CT scans
This article examines the role that imaging plays in diagnosing and tracking PsA.
Peripheral vs. axial PsA
Doctors often classify PsA as peripheral or axial depending on which joints the condition affects.
Peripheral disease affects the joints in your extremities, like your hands or feet. Axial disease affects your spinal cord. Some people have both types.
Peripheral PsA is more common, but
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X-rays are the
Around one-quarter of people with early PsA have joint damage that shows up on X-rays, and about half of people have visible damage within 2 years, according to a notable 2003 study.
X-rays are advantageous because they’re:
- fast
- relatively inexpensive
- reliable
- widely available
Doctors can use X-rays to identify
- joint destruction
- bone erosion
- new bone formation
- joint space narrowing
- pencil-in-cup deformity, a characteristic feature of PsA that develops in the small joints in your hands
X-rays require exposure to a small amount of radiation. For this reason, doctors may prefer MRI for spinal cord evaluation in children and
Axial PsA
Changes to your spine visible on an X-ray include:
- new bone formation
- changes to multiple levels of your spine
- joint changes on one side, which
highly suggests PsA
A CT scan is a series of X-rays that produces a 3D image of your joint.
CT scans are great for seeing:
- bone erosions
- new bone formation
- joint space changes
The role of CT scans in diagnosing PsA is
CT scans might be helpful in complex and
- shoulder girdle
- spine
- pelvis
- sacroiliac (SI) joint
MRI uses powerful magnets to create an image of the inside of your body. MRI is
MRI is more sensitive than X-ray for detecting early joint inflammation and damage.
Doctors
Ultrasound uses high frequency sound waves to create an image of your tissues. Ultrasound is:
- quick
- cheap
- widely available
Ultrasound also allows doctors to scan multiple sites in one session. Like MRI, ultrasound is more sensitive than plain X-ray for detecting early joint inflammation. Ultrasound is a useful technique for evaluating inflammatory changes in
- joint lining
- tendons
- bursas
- entheses, where tendons or ligaments connect to bone
The main drawbacks of ultrasound are that it can’t penetrate bone and it doesn’t help doctors identify changes to your spinal cord well.
When might a doctor recommend radiologic tests for psoriatic arthritis?
Imaging plays a vital role in the early diagnosis of PsA. Your doctor may send you for imaging if you have characteristic features such as:
- joint pain and swelling
- nail and skin changes
- a personal or family history of psoriasis
- uveitis, inflammation of the middle layer of your eye
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Doctors can use imaging to look for characteristic signs of PsA to help distinguish it from other types of inflammatory arthritis.
For example, seeing the “
Another characteristic sign of PsA is the pencil-in-cup deformity. This happens when a bone in your finger is narrow and the bone below it is wide.
Doctors can
Other tests you may receive to support your diagnosis include:
- a physical exam
- gene tests for HLA-B27
- skin biopsy
- laboratory tests to examine erythrocyte sedimentation rate or C-reaction protein levels
After imaging, your doctor may recommend medications to help manage your symptoms, such as:
- nonsteroidal anti-inflammatory drugs (NSAIDs)
- disease-modifying antirheumatic drugs (DMARDs)
- a class of biologics called tumor necrosis factor (TNF) inhibitors
They may also recommend making an effort to incorporate certain lifestyle changes, such as:
- quitting smoking, if you smoke
- maintaining a moderate weight
- exercising regularly
X-rays are the most common type of imaging doctors use to diagnose and monitor PsA. Doctors also use other types of imaging such as CT scans, ultrasound, or MRI.
Your doctor might recommend further imaging if initial X-rays are inconclusive. Other scans, such as MRI or ultrasound, can better show inflammation in your soft tissues.
Your doctor may recommend MRI instead of X-rays as your initial scan if they want to limit your radiation exposure.
