[Magnetic resonance imaging for active ankylosing spondylitis]

Area of Science:

• Rheumatology
• Radiology
• Medical Imaging

Background:

• Active ankylosing spondylitis (AAS) diagnosis can be challenging in early stages.
• Magnetic resonance imaging (MRI) is a key tool for detecting sacroiliitis.
• Radiographic evidence of sacroiliitis is not always present in early or probable cases.

Purpose of the Study:

• To evaluate the diagnostic utility of MRI for active ankylosing spondylitis (AAS).
• To determine the effectiveness of sacroiliac joint (SIJ) MRI and thoracic spine MRI in diagnosing AAS.
• To assess the sensitivity and specificity of MRI in patients with probable AS and no initial radiologic sacroiliitis.

Main Methods:

• MRI of the SIJ was performed on 48 patients with probable AS and no radiologic sacroiliitis.
• Patients without active SIJ inflammation on MRI underwent thoracic spine MRI.
• Diagnostic criteria for AAS by MRI were established, and diagnoses were confirmed after a six-month follow-up.

Main Results:

• Of 48 patients, 38 were diagnosed with AAS.
• MRI of the SIJ alone had a sensitivity of 52.6% and specificity of 90.0%.
• Combined MRI of the SIJ and thoracic spine achieved a sensitivity of 76.3% and specificity of 90.0%.

Conclusions:

• MRI of the SIJ and thoracic spine is valuable for diagnosing AAS, especially when initial SIJ imaging is negative.
• Thoracic spine MRI significantly enhances the sensitivity for AAS detection in patients with probable AS but without evident sacroiliitis.
• MRI offers improved diagnostic accuracy for active ankylosing spondylitis.