Clearance of (125)i-labelled urographin from knee joints in rheumatoid arthritis

(125)I-labelled Urographin has been used intra-articularly as tracer and 60 per cent Urographin as contrast in ten knee joints of patients with classical rheumatoid arthritis. Nine traumatic knees served as controls. The rapid rate of disappearance of the contrast from joints with rheumatoid inflammation was higher than in controls. Over the rheumatoid joints the radioactivity had decreased to half the initial value in 2.85 hrs. and over the traumatic joints in 3.70 hrs. In the radiographs clear evidence of absorption of contrast by the synovial membrane, the hyaline cartilage and the fibrocartilaginous tissue of the menisci was demonstrated. In one case visual proof was obtained of drainage of the contrast through the local lymphatics. The series of arthrograms taken from this knee indicate that this drainage was rapid.