Figure 13b. Rheumatoid arthritis in a 62-year-old woman with long-standing disease. (a) Transverse 12-5-MHz US image obtained over the posterior shoulder reveals a hypoechoic soft-tissue mass that represents synovial pannus within the posterior recess (arrowheads). In addition, there is a defect (arrow) of the posterior humeral head (HH), a finding that represents erosion. G = glenoid. (b) Corresponding GRE MR image (500/15/20°) demonstrates the soft-tissue mass (arrowheads).