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Imaging Tests to Diagnose and Track Rheumatoid Arthritis

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By Editorial Team

2 min read

Reviewed by: HU Medical Review Board | Last reviewed: July 2024 | Last updated: August 2024

Imaging tests are commonly used to diagnose and track rheumatoid arthritis (RA). Some tests may be more useful in early stages of the disease. Others are better for tracking RA symptoms over time and for measuring how well you respond to treatment.1

The imaging tests most often used to diagnose RA are:1,2

  • X-rays
  • Ultrasounds
  • Magnetic resonance imaging (MRI) scans

Your doctor will likely order imaging tests of your hands and feet first. This is because these are the joints RA tends to attack first. In RA, joint damage is symmetrical. This means it occurs fairly evenly on both sides of the body. Imaging tests are used in combination with blood tests and a physical exam to diagnose RA.1,2

Early RA diagnosis means early treatment. This can help prevent or slow future joint damage.2

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X-rays

For years, X-rays were the only imaging test available to diagnose and monitor the progress of RA. The problem is that, in the early stages of RA, the joints may appear normal on X-rays. This meant people were diagnosed with RA only when joint damage was visible on X-rays, which means only when RA was more advanced.1,2

The first signs of RA on X-rays tend to be joint swelling and bone loss at the joints of the hands or feet. In more advanced RA, X-rays will also show:1

  • Narrowing space between the joints
  • Wearing down (erosion) of the bone
  • Misaligned joints

Today, ultrasound and MRI can show early signs of inflammation and erosion of the bones. This now makes early diagnosis and treatment of RA possible. But X-rays are still useful in providing a baseline and in tracking if joint damage is getting worse over time.2

Ultrasound

A musculoskeletal ultrasound (MSUS) is more sensitive than X-rays in diagnosing and tracking RA. Ultrasound is especially useful in diagnosing RA early when combined with lab tests and a physical exam. This is especially true for those who do not test positive for RA antibodies.2

Ultrasound can spot inflammation when the joints are not tender or swollen on a physical exam. It can estimate the degree of inflammation and the amount of inflamed tissue. Ultrasound results can also help your doctor predict:1,2

  • How your RA will progress
  • How you might respond to RA treatment
  • Your chances of a flare if you reduce or stop your medicine

Ultrasound is convenient since most rheumatology offices have an ultrasound machine. This test is painless and costs less than an MRI. But it is usually more expensive than X-rays.2

MRI

MRI scans are as good as ultrasounds at detecting early signs of RA. But they are more expensive than ultrasounds or X-rays. Plus, MRI scans are usually performed at an imaging center, which requires an extra appointment. MRI scans can also be hard for people with fear of closed spaces (claustrophobia).2

American and European rheumatology groups recommend MRI be used only for cases that are hard to diagnose, not for routine use.2

Other imaging tests for RA

Other types of imaging tests may be used to diagnose and track RA symptoms. These tests include:2,3

  • Computed tomography (CT) scans
  • Positron emission tomography (PET) scans
  • Bone scans
  • Dual-energy X-ray absorptiometry (DEXA) scans

But ultrasounds and X-rays still remain the gold standard for diagnosing and treating RA.2,3