What is the best way to diagnose Ankylosing Spondylitis?

The diagnosis of Ankylosing Spondylitis (AS) is primarily confirmed through imaging studies that focus on the sacroiliac joints, which are often affected in this condition. Sacroiliac X-rays can reveal changes such as erosions, sclerosis, and eventual fusion of the joints that are characteristic of AS. These changes are pivotal as they provide visual evidence supporting the diagnosis.

In addition to X-ray findings, the presence of certain clinical features, such as inflammatory back pain, and guidelines from organizations like the Assessment of SpondyloArthritis International Society (ASAS) also aid in making a definitive diagnosis. However, the imaging aspect, especially through sacroiliac X-rays, directly highlights specific joint involvement, making it the best choice for confirming AS.

The other imaging and biopsy options listed—such as chest X-rays, salivary gland biopsies, and temporal artery biopsies—are not relevant or effective for diagnosing Ankylosing Spondylitis, as they target entirely different conditions and systems within the body. Thus, the focus on sacroiliac X-rays aligns best with the diagnostic criteria for AS.