Fig. 1

Representative images of severe monoarthritis in children diagnosed with oligoarticular juvenile idiopathic arthritis. a X-ray of the hips showed shortening of the left femoral neck and decreased joint space; b MRI with gadolinium revealed enhancement and mild thickening of the left hip synovium on T2-weighted imaging; c MRI of the right wrist demonstrated carpal synovitis, marked bone marrow edema, bone cysts and erosions on T1-weighted imaging; d Non-contrast CT of the left elbow showed bone erosions, hyperostosis of the trochlear-olecranon complex and reduced joint space. White arrows point towards the abnormal findings