Large right knee effusion with an intra-articular frond-like mass of soft tissue that appears to emanate from the posteromedial aspect of the synovium. The frond-like portions of this mass are relatively low on T2 signal and high on T1 signal. The fronds of this mass enhance in a striking pattern with intense peripheral surface enhancement and little, if any, central enhancement of the individual papules covering the surface of the soft tissue mass. There is no blooming artifact on the gradient echo sequences.
The soft tissue mass surrounds the posterior cruciate ligament and distends the posterior aspect of the knee joint. The lateral synovium of the distended right knee joint enhances brightly and has a smooth, non-nodular contour. There are no articular erosions. The menisci, cruciate ligaments, and collateral ligaments are grossly normal in appearance.