The gold standard test for ankylosing spondylitis is an X-ray. An X-ray is a diagnostic imaging technique used to take pictures of the bones and other body structures. During an X-ray, a very small dose of ionizing radiation is used to create an image of the inside of the body.
An X-ray is the most accurate way to diagnose ankylosing spondylitis because it can show the changes in the joints and other bones that are characteristic of the disease. A plain X-ray can often show changes in the lower back, such as bone spurs, erosion, and other signs of ankylosing spondylitis. In some cases, a contrast-enhanced X-ray, which uses a special dye injected into the bloodstream, may be used to provide better results.
An X-ray can also help to monitor the progression of ankylosing spondylitis. Over time, changes in the bones and joints can be monitored to determine if the disease is worsening or responding to treatment.
In addition to an X-ray, blood tests, physical examination, and imaging tests such as magnetic resonance imaging (MRI) and computed tomography (CT) scans may also be used to diagnose ankylosing spondylitis.