Sacroiliac Joint MRI

Dedicated MRI of both sacroiliac joints for sacroiliitis, ankylosing spondylitis, and inflammatory spondyloarthropathy assessment. Follows ASAS imaging criteria.

The dedicated sacroiliac joint MRI provides targeted high-resolution imaging of both SI joints using sequences optimized for detecting early inflammatory changes. The protocol includes coronal oblique T1-weighted images for structural assessment (erosions, sclerosis, ankylosis) and STIR sequences for active inflammation (bone marrow oedema adjacent to the joint surfaces). This examination follows the Assessment of SpondyloArthritis international Society (ASAS) criteria for defining a positive MRI, which requires bone marrow oedema clearly present in a location typical for sacroiliitis — the subchondral or periarticular bone of the sacroiliac joint. The radiologist documents whether the pattern meets ASAS criteria, the distribution and extent of oedema, and any structural changes suggesting chronic disease. The scan is typically requested by rheumatologists for patients with suspected axial spondyloarthropathy, HLA-B27 positive individuals with back pain, and for monitoring treatment response in known ankylosing spondylitis. It is also useful for differentiating sacroiliitis from mechanical SI joint dysfunction or referred pain from the lumbar spine.