Coronal magnetic resonance imaging (MRI) of the metacarpophalangeal (MCP) joints. (a) T1-weighted image from the MCP joints in early rheumatoid arthritis, and (b) corresponding fat suppression image at baseline. (c) Corresponding T1-weighted image at 6 months, and (d) fat suppression image at 6-month follow-up. The diffuse low signal at sites of MRI erosion in (a) (arrows) is better demarcated in (c) (arrowheads). The osteitis process at the 2nd, 3rd, and 4th MCP heads in (b) (arrows) has either improved or dramatically regressed in (d) (arrowhead). These images depict the inflammatory component to the MRI erosive process.