Arthritis is a collection of diseases characterized by the inflammation of joints. There are more than a 100 different subtypes of arthritis, with the most common ones being osteoarthritis and rheumatoid arthritis. Arthritis can often be a difficult condition to diagnose and the process requires conducting a physical examination, medical history, blood tests and imaging tests.
Imaging tests for arthritis are conducted in order to look for signs of:
- Bone erosion
- Tissue damage
- Joint deterioration or degradation
Additionally, physicians will order imaging tests in order to monitor for signs of disease progression over time. These are some of the benefits of imaging tests:
- Physicians are able to determine the pattern of deterioration of the joint, as that can provide evidence for the type of disease that a patient has.
- Physicians are able to identify the presence of bone erosion early on in the disease course, which is crucial as bone erosion is irreversible if caught later on.
- Imaging tests allow physicians to initiate treatment early on, which is a lot more effective in the earlier stages of the disease.
Imaging tests to diagnose and monitor arthritis
There are several different types of imaging tests that can help diagnose as well as monitor progression of arthritis.
X-rays are known as radiographic tests due to the fact that they use a low dose of radiation. X-rays provide a two-dimensional picture of the joints and show bones and how they interact with each other at the joints. They are used so that a physician can determine whether there is bone erosion in the joints. In fact, X-rays not only show the location at which bone erosion is developing but also provides clues as to how quickly the erosion is taking place over time.
X-rays are standard tests for imaging of joints in patients with arthritis due to the fact that they are easily conducted and affordable. X-rays are also able to show whether there are any underlying conditions in the bones that are causing the development of arthritis. However, while X-rays are the preferred manner of imaging joints, they are often not good at showing early signs of some subtypes of arthritis, such as rheumatoid arthritis, as the damage is only visible later on in disease progression. Hence, often, physicians are not able to catch disease early on and only find it when it has progressed to the point of permanent damage.
Magnetic Resonance Imaging (MRI)
MRIs provide a three-dimensional image of the joints and the bones. They are a more advanced technique of imaging and therefore, provide more details about the joint in question. In fact, while X-rays are used mostly just to look at bone, MRIs are able to determine the presence of abnormalities in the soft tissue, including the muscles, tendons and joint capsules, all of which are affected when they surround arthritic joints.
One of the most beneficial things about using MRIs in the case of arthritis is that they are able to actually detect signs of arthritis early on. For example, one of the earliest signs of degradation of bones or bone erosion is the build-up of fluids in the bone marrow. While X-rays will not be able to discern fluid build-up, MRIs are able to pick that up. Additionally, MRIs can actually identify sites of active inflammation or early signs of inflammation in a joint. Importantly these early signs develop before any permanent damage occurs, and therefore, can be treated clinically.
X-rays and MRIs are more traditionally used in a diagnosis of arthritis. However, more recently, physicians have started to use ultrasounds as a way of diagnosing arthritis as well monitoring disease progression. Ultrasounds involve the use of high-frequency sound waves that are then transformed into pictures of the inside of a patient’s body in a manner that is similar to how bats are able to locate things in their surroundings.
One of the benefits of ultrasounds is that, unlike x-rays, they do not use radiation to construct an image. Additionally, ultrasounds are significantly better at detecting the earlier signs of erosion compared to x-rays as they are able to show inflammation of joints. This is particularly important when it comes to monitoring disease progression as often, ultrasounds will show visible signs of remission (symptom improvement) on the joints. This can be quite helpful as signs of remission can indicate to physicians that the patient can reduce their dosage of treatment or stop treatment altogether for a while. Conversely, if the patient continues to show damage to joints despite treatment, then the physician will know to continue treatment or change treatment for better results.