Case discussion
01Clinical context
MRI of the sacroiliac joints without intravenous contrast, performed to evaluate suspected inflammatory back pain.
02Key imaging findings
Fluid-sensitive sequences demonstrate bilateral periarticular bone marrow oedema along both the sacral and iliac aspects of the sacroiliac joints, consistent with active inflammatory sacroiliitis. Joint alignment and articular surfaces are maintained, with no definite erosions, fatty metaplasia, or ankylosis, and no significant joint effusion or periarticular soft-tissue collection.
03Teaching point
Bone marrow oedema on fluid-sensitive sequences is the hallmark of active sacroiliitis and can precede structural change by years. Documenting active inflammation in the absence of erosions, sclerosis or ankylosis identifies early, potentially treatment-responsive disease and supports a diagnosis of axial spondyloarthritis in the correct clinical setting. Reporting both the active (oedema) and structural (erosion, fat metaplasia, ankylosis) domains gives the referring rheumatologist the fullest picture.
Shown for education. De-identified — no identifiable patient data. A radiology report is a specialist opinion and must be read with the full clinical context by the treating physician.