Spinal inflammation lesions as detected by magnetic resonance imaging in patients with early ankylosing spondylitis are more often observed in posterior structures of the spine.

Objective: To study the localization and extent of spinal inflammation in patients with AS in detail.

Methods: This cross-sectional study used standardized clinical tools and MRI, including T1 and T2 fat saturation sequences in both sagittal and axial planes. A simple method of analysis of MRI changes was performed using the principle of 'yes/no' to calculate the changes in vertebral body and posterior structures of spine, including costovertebral and costotransversal joints.