Fig. 2

Expanding versus collapsed popliteal LNs in early versus late-stage RA knee flare. MRIs were obtained from RA patients with new-onset (a,b) and long-standing (>20 years) (c,d) asymmetric knee flare, who were enrolled in a phase 4 clinical trial to assess the effects of anti-TNF therapy on PLN volume (ClinicalTrials.gov NCT01098201). The 2D sagittal views (a,c) and 3D volume renderings (b,d) illustrate the dramatic differences between early RA flare with expanded PLN (pink, green and yellow arrows corresponding to pseudocolored PLN) adjacent to highly inflamed synovium and focal erosions in the lateral femoral condyle (*), compared with the barely visible collapsed PLN (blue and yellow arrows corresponding to pseudocolored PLN) adjacent to advanced pannus tissue and extensive bone erosions