Sample imaging depicting bone defect on magnetic resonance imaging before radiographic erosion. Images (a-c) were taken 1 year before images (d-f). Image (a) is T1-weighted and has a small defect (arrow). Image (b) is T2-weighted with fat saturation clearly showing synovitis (arrow). Image (c), the radiograph, was read as normal because the cortex was intact. Image (d), T1-weighted, clearly shows absence of bone read as erosion (arrow). Image (e) shows synovitis and bone marrow edema (arrow). Image (f) clearly shows bone erosion (arrow).