The Use of Imaging to Detect Rheumatoid Arthritis
Rheumatoid arthritis is a painful condition that affects the joints, most often the feet and hands. The symptoms include painful swelling of the joints, stiffness, and sometimes weight loss and fatigue. Early diagnosis of this debilitating condition is critical. The longer it takes to secure a diagnosis the more likely it is that the patient will end up with long-term joint damage.
There are a number of ways to diagnose rheumatoid arthritis, but imaging scans are an important part of the process. Blood tests are used in the first instance to detect the presence of C-reactive protein (CRP), which is an inflammatory marker, and anti-CCP antibodies. Positive blood tests results don’t provide a definitive diagnosis, but if they are suggestive of rheumatoid arthritis, joint imaging scans will be carried out before the patient books a surgeon for a knee operation.
X-rays have been used for decades, but although they are useful in providing a baseline picture of what the joint looks like, they are less useful in aiding a diagnosis, particularly in the early stages of the disease’s progression. The fact that an X-ray only takes an image from one angle is another limitation. Nevertheless, X-ray is an important imaging tool for the monitoring of rheumatoid arthritis disease progression.
Once it becomes apparent that patients have more serious joint abnormalities, doctors will recommend that a patient has an ultrasound and MRI scan.
Ultrasound imaging is a low cost, radiation free, alternative to MRI scans. Recent advances in ultrasound imaging technology allow doctors to view inflamed joints in far greater detail, which is very useful in monitoring disease progression.
In a recent study that compared X-ray imaging and ultrasound in 100 patients with rheumatoid arthritis, ultrasound detected 127 abnormalities compared to just 32 abnormalities in patients scanned using X-rays. The researchers concluded that ultrasound was much better at detecting abnormalities in early stage rheumatoid arthritis. However, the accuracy of diagnosis does depend on the skill of the ultrasound technician and the equipment used.
Further clinical testing will be used before doctors can determine whether ultrasound testing is more effective than X-ray testing for the monitoring of early-stage joint destruction. In the meantime, X-ray analysis continues to be used to measure disease progression.
Magnetic resonance imaging (MRI) scans are useful for diagnosing rheumatoid arthritis, but the cost of the procedure is a prohibitive factor. An MRI scanner uses a large magnet and radio waves to produce incredibly detailed images of the body. MRI scans are risk-free and can be used as often as is needed. In fact, repeat MRI scans are very useful in tracking the progression of the disease.
MRI scans and ultrasound can both detect inflammation, bone erosion, and tendon abnormalities, but an MRI scan will detect edema in the bone marrow that predicts the presence of bony erosions so typical of rheumatoid arthritis.
An X-ray may be the first imaging technique used, but patients will have follow-up tests using ultrasound imaging. If there are any questions as to the severity of disease progression or the type of arthritis the patient has, an MRI scan may be ordered.