Whether it’s magnetic resonance imaging (MRI), an ultrasound or a good old-fashioned X-ray, your doctor is likely to order some type of medical imaging to see what’s going on below the surface with your arthritis.
“The most important thing rheumatologists can do to assess patients is still a good history and clinical exam. The role of imaging is to assist in assessing the degree of severity,” says Orrin Troum, MD, professor of medicine at University of Southern California and spokesperson for the International Society for Musculoskeletal Imaging in Rheumatology. Understanding its severity helps a doctor decide how aggressively to treat the disease.
X-rays give a two-dimensional picture of your joints. They show joint space narrowing (a sign of arthritis), erosions, fractures, lower-than normal bone density and bone spurs.
Because they’re easily available and affordable, X-rays are usually the first imaging technique used to assess osteoarthritis or forms of inflammatory arthritis, including rheumatoid arthritis (RA), psoriatic arthritis and ankylosing spondylitis.
But while X-rays can show where damage has occurred, ultrasound and MRIs can detect joint changes sooner, possibly giving you a chance to prevent further joint damage.
In recent years, the use of ultrasound (also called sonogram) has skyrocketed among rheumatologists evaluating inflammatory arthritis. Ultrasound, which uses high-frequency sound waves to create an image, is most useful at showing inflammation in tendons and the tissue that lines the joint, called the synovium.
Ultrasounds can help narrow down a diagnosis. For example, in cases of low back pain, ultrasound can show if there is inflammation at the sites where tendons or ligaments attach to the bone, which could mean a type of spondyloarthritis. And when ultrasound detects inflammation of the synovium along with erosions, it could mean you’ve got RA instead of some other type of inflammatory arthritis.
Ultrasound also is commonly used for spotting uric acid crystal deposits and joint erosion from gout, and to help guide joint injections.
MRIs give 3-D images of bones, joints and soft tissues by using a magnetic field and radio wave pulses. MRIs can show infections, tears in soft tissues like the meniscus or a tendon, and bone marrow edema. This fluid build-up in the bone marrow is the best predictor of future erosion, says Dr. Troum; it may prompt your doctor to pursue more aggressive treatments earlier on.
“X-rays may eventually disappear in rheumatology,” says Dr. Troum, because MRI and ultrasound show far more detail. But higher costs and insurance restrictions limit their use in many cases. Other technologies, such as specialized PET and CT scans, also are being investigated for their uses in rheumatology, he adds.
Author: SHAHREEN ABEDIN