Figure 6. Long-standing RA in a 52-year-old woman. Coronal contrast-enhanced fat-saturated T1-weighted MR image shows synovitis of the second and third metacarpophalangeal joints. A subcortical cyst (arrowhead) is seen near the bare area. This type of lesion is called a pre-erosion or subcortical erosion by some authors owing to the high likelihood that it will progress to a clear erosion.