Figure 7b. Diffuse PVNS of the knee in a 43-year-old woman. (a) Sagittal proton density-weighted MR image shows lobulated, masslike synovial proliferation with characteristic low signal intensity. Note the tibial articular erosions. (b) Corresponding coronal T2-weighted MR images through the anterior right knee demonstrate massive distention of the suprapatellar pouch by lobulated proliferative synovium with characteristic low signal intensity because of hemosiderin deposition.