Arthritis can be detected by CT scan, which can help diagnose arthritis by detecting cartilage degeneration, narrowing of the joint space, and osteophytes and calcifications in the joint area. However, CT scan only reveals changes in bone structure, but the diagnosis of arthritis formed by soft tissue problems is not clear. It is best to perform MRI of the joint to see the inflammation of soft tissue in the joint and the amount of fluid in the joint, which is very useful for diagnosis and treatment. For example, if arthritis is present in the knee joint, a plain film examination can be done to see the changes in the bone structure, instead of CT, which is more expensive and has a greater impact on the body. If there is significant redness and swelling in the joint, especially if there is fluid in the joint, it is best to have an MRI of the knee joint to see if there is synovitis as well as strain and inflammation of the meniscus, cruciate ligament, joint capsule and other structures.