From the Guidelines
Diagnosing ankylosing spondylitis requires a combination of clinical evaluation, imaging tests, and blood work, with the most recent guidelines recommending the use of MRI scans to detect inflammation before structural damage occurs 1.
Key Diagnostic Steps
- Clinical evaluation: assessing symptoms like chronic low back pain that improves with activity, morning stiffness lasting more than 30 minutes, and pain that wakes you at night
- Blood work: HLA-B27, a genetic marker present in about 90% of people with ankylosing spondylitis, as well as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) to measure inflammation levels in the body
- Imaging tests: X-rays to show changes in the sacroiliac joints and spine, and MRI scans to detect inflammation before structural damage occurs
Importance of Early Diagnosis
Early diagnosis is crucial as treatment with NSAIDs and biologics like TNF inhibitors can help manage symptoms and potentially slow disease progression 1.
Role of MRI in Diagnosis
MRI scans play a critical role in the diagnosis of ankylosing spondylitis, particularly in detecting early inflammatory disease when radiographic evidence of disease is absent 1.
Recommendations for Diagnosis
The American College of Radiology recommends the use of MRI scans to evaluate for possible axial spondyloarthropathy, with the request indicating that the examination is being performed to evaluate for this condition 1.
From the Research
Ankylosing Spondylitis Diagnosis
- Ankylosing spondylitis (AS) is a chronic inflammatory condition that primarily affects the axial bone and sacroiliac joints 2.
- The diagnosis of AS is based on a combination of clinical symptoms, imaging studies, and laboratory tests 3, 2.
- Imaging studies, such as conventional x-rays and magnetic resonance imaging (MRI), are important for detecting chronic structural changes and active inflammation in the sacroiliac joints and spine 3, 4, 5.
- MRI is particularly useful for detecting early inflammatory changes and active sacroiliitis or spondylitis in early disease stages 3, 4.
Imaging Techniques
- Conventional x-rays are mainly useful for detecting chronic structural changes, such as shiny corners and syndesmophytes, in the spine 3.
- MRI techniques, such as STIR and T1 post-gadolinium sequences, are able to detect active inflammation and structural changes in the sacroiliac joints and spine 3, 4.
- The modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) is a scoring method used to quantify structural changes in the spine 3.
- New scoring methods, such as those using MRI, are sensitive to change and can be used to monitor the effectiveness of treatment 3, 4.
Diagnostic Criteria
- The diagnosis of AS is based on a combination of clinical symptoms, imaging studies, and laboratory tests, including the presence of HLA-B27 2.
- The HLA-B27 gene is associated with AS susceptibility, and approximately 80-95% of people with AS have this marker 2.
- Elevated inflammatory markers, such as C-reactive protein and erythrocyte sedimentation rate, can also support the diagnosis of AS 2.
- Recent studies have also explored the use of deep learning models and combined conventional MRI sequences for the diagnosis of AS 6.