Imaging is one of the powerful tools your rheumatologist can use to confirm your rheumatoid arthritis (RA) diagnosis and track disease progression, or changes to your body caused by rheumatoid arthritis disease activity over time.
Newer, more sophisticated imaging technologies may show signs of RA very early on. This is great news—the earlier inflammation is detected, the sooner it can be treated with medications to help prevent joint or tissue damage.¹
What is imaging?
Imaging is any kind of scanning technology that shows what’s going on inside your body, in bones, soft tissues or internal organs. These include X-rays, ultrasound, MRI, CT, and PET.² Each one has advantages and challenges, including accuracy, technician skills required and cost.³
Imaging can show bony erosions, small areas of bone loss caused by RA inflammation. Erosions are signs of severe RA, and they can lower joint function.
Imaging may also detect bone changes like osteopenia, or weakening bones, or joint malalignment and stress fractures.
Imaging can also show signs of active RA in soft tissues that cushion your joints as you move around or use them.
- Synovium: Synovium is the tissue that lines the inside of joints. Synovitis, or inflamed synovium tissue, is common for people with RA. If inflammation persists, synovium tissue can swell and thicken.
- Joint space changes: The spaces inside joints can be seen and measured on scans. Joint space narrowing may happen as the cartilage wears down. In early RA, joint space may widen due to thickened synovium or joint fluid.
- Tendons: Imaging can show inflammation in thin sheaths around tendons, called tenosynovitis.
- Cartilage: Cartilage is the thick, tough, flexible tissue that also cushions many joints. Cartilage acts as a buffer between the ends of bony joints as they move. In RA, synovitis, and thickening synovial tissue can wear down cartilage. This can lead to joint damage and pain.
- Joint Fluid: RA may also cause joint effusion or fluid build-up in your joint. Your doctor may be able to spot excess fluid on your imaging scans.
- Marrow: Some sensitive imaging tests can show bone marrow edema or fluid build-up in the spongy tissue inside bones caused by RA inflammation.
RA affects the whole body, not just joints. RA can cause inflammation in the heart, lungs, eyes or other organs. If RA disease activity isn’t controlled through treatment, it may lead to heart disease or other serious health problems, as discussed below.
In a 2019 study, doctors used PET-CT scans to detect subclinical myocardial (heart) inflammation4
in people with RA who hadn’t been diagnosed with any type of heart disease. Subclinical myocardial inflammation is one sign of RA disease activity. The study also showed that people with RA who used biologic therapies instead of conventional DMARDs had lower levels of myocardial inflammation.
Another 2019 study even used MRI5
to show unusual stiffness in the aorta, the major artery to the heart, in people at risk for RA. They had tested positive for the anti-CCP antibody but no synovitis. Aorta stiffness is usually seen in people with long-term, not early, RA.
Primary Imaging Tests
X-rays: Also called radiographs, X-ray is the oldest type of imaging technology. It uses electromagnetic radiation waves to take black and white pictures of bones and joints. X-rays show bone problems well, but they often happen once RA is farther along. X-ray is less useful for detecting earlier, soft-tissue changes in RA. X-rays use radiation, in small doses. Lead aprons can protect the body during an X-ray.
Ultrasound: Also called sonography or ultrasonography (US), this technology uses sound waves to take images of joints, soft tissues, and internal organs. It does not use radiation. Ultrasound helps diagnose RA and track disease progression. ultrasound is more accurate than X-rays in showing bony erosions and it can also show areas of inflammation in the joint.
MRI: Magnetic Resonance Imaging (MRI) is the most sensitive scan both to help diagnose RA and to track disease progression. MRI uses magnetic and radio waves to take images of bone, soft tissue, and internal organs. It’s often used to help confirm RA diagnosis because it has a high level of accuracy. MRI scans show subtle differences in the joints’ soft tissues. Even in early RA, your doctor can use these very accurate images to tell if you have synovitis, joint effusion or tenosynovitis, an inflammation of the tissue covering the tendons. MRI is the best scan for detecting bone marrow edema. MRI can show bone changes early in RA. It’s more sensitive than X-ray or ultrasound at picking up erosions in hands or wrists. MRI can even detect inflammation when RA is in remission.6
CT scan: Computed Axial Tomography, also called a CT or CAT scan, uses ionizing radiation to take many X-ray images from different angles. A computer combines all the pictures to make detailed images of a section of the body. Doctors may use CT less often in early RA. CT scans accurately show bone structure changes caused by RA, especially in the neck joints, but it’s less sensitive at picking up soft-tissue changes.
PET scan: Positron Emission Tomography is a newer type of scan. This imaging technology uses a radioactive chemical called a radiotracer that highlights structures in the tissue on the scan. PET/CT scans are highly sensitive, so they can help detect very subtle changes from RA inflammation at the cellular level—before there are structural changes that MRI or CT scans could pick up. One new kind of PET scan uses a radiotracer called 18 F-fluorodeoxyglucose (FDG). FDG-PET scans can help your rheumatologist assess your RA, along with molecular tests like Vectra.
In a 2012 study of people with RA, FDG-PET scans were used not only to help detect disease activity, but to confirm how well the patients’ joints responded to different RA medications infliximab and etanercept. To take a PET scan, a tiny amount of radiotracer is injected into a vein. About 45 minutes later, the machine scans the body, and picks up energy from the radiotracer. A computer creates 3D images from the scans.
Imaging is just one tool that you and your rheumatologist can use to track RA disease progression. Vectra accurately measures your RA disease activity and inflammation and tracks it over time. This advanced blood test for adults with RA measures 12 important markers of disease activity, then combines them into one simple score. Use your myVectra app to keep track of your Vectra Scores, symptoms and other important information to share with your rheumatologist.
Sudol-Szopinska I, Jans L and Teh J. “Rheumatoid arthritis: What do MRI and ultrasound show.” J Ultrason. 2017 Mar;17(68):5-16.
Colebatch AN, Edwards CJ, Ostergaard M, et al. “EULAR recommendations for the use of imaging of the joints in the clinical management of rheumatoid arthritis.” Ann Rheum Dis. 2013;72:804-814.
Haugen IK and Hammer HB. “A need for new imaging modality to detect inflammation in rheumatoid arthritis and osteoarthritis?” Ann Rheum Dis. 2016;75:479-480.
Amigues I, Tugcu A, Russo C, et al. “Myocardial Inflammation, Measured Using 18- Fluorodeoxyglucose Positron Emission Tomography With Computed Tomography, Is Associated With Disease Activity in Rheumatoid Arthritis.” Arthritis Rheumatol. 2019 Apr;71(4):496-506.
Fent G, Mankia K, Erhayiem B, et al. “First cardiovascular MRI study in individuals at risk of rheumatoid arthritis detects abnormal aortic stiffness suggesting an anti-citrullinated peptide antibody-mediated role for accelerated atherosclerosis.” Ann Rheum Dis. Published Online First: 09 March 2019. doi: 10.1136/annrheumdis-2018-214975.
Vyas S, Bhalla AS, Ranjan P, et al. “Rheumatoid Arthritis Revisited: Advanced Imaging Review.” Pol J Radiol. 2016:81:629-635.