Sacroiliitis in children, often linked to juvenile idiopathic arthritis subtypes like enthesitis-related arthritis, psoriatic arthritis, or undifferentiated arthritis, is primarily diagnosed using magnetic resonance imaging (MRI). MRI can reveal bone marrow edema as a sign of active inflammation. Other findings may include joint space narrowing, erosions, and joint fluid. While radiographs are helpful for initial assessment, MRI is more sensitive for detecting early sacroiliitis. In this example, the left iliac bone has edema and enhances with contrast. The short video clip also highlights erosions.
