FAQs
What are the main imaging techniques used in diagnosing ankylosing spondylitis?
X-ray imaging identifies sacroiliitis at later stages, while MRI detects early sacroiliac joint inflammation (bone marrow edema) making it key for early diagnosis.
How long must back pain last to meet the diagnostic criteria for AS?
The back pain must last at least three months, show inflammatory characteristics such as improvement with exercise but not rest, and often include morning stiffness.
What role does the HLA-B27 test play in diagnosing ankylosing spondylitis?
HLA-B27 is a genetic marker present in about 90% of people with classic AS. It supports diagnosis but is not definitive alone, requiring clinical and imaging correlation.
What is the difference between the Modified New York criteria and ASAS criteria?
The Modified New York criteria rely mainly on X-ray evidence and clinical signs, suitable for established disease. The ASAS criteria incorporate MRI and genetic tests and are better for early or non-radiographic cases.
Can ankylosing spondylitis be diagnosed solely with blood tests?
No. Blood tests like HLA-B27 and inflammation markers support the diagnosis but must be combined with clinical patterns and imaging findings for confirmation.
