99mTc-Infliximab-scintigraphy for the demonstration of tumor necrosis factor alpha in patients with rheumatoid and psoriatic arthritis

42 Objectives: Infliximab (Remicade®) is a monoclonal antibody directed against tumor necrosis factor alpha (TNF α). It has become an established treatment for patients with rheumatoid arthritis, psoriatic arthritis and undifferentiated spondylarthritis. However, neither clinical parameters nor imaging modalities really indicate which patient may benefit from therapy with Infliximab. Aim: To investigate the feasibility of infliximab-scintigraphy to image TNF alpha expression in patients presenting with rheumatoid or psoriatic arthritis. Methods: A total of 12 patients were included in the present study. Seven patients with rheumatoid arthritis, 3 with psoriatic arthritis and 2 patients with degenerative arthrosis underwent 99m-Tc-infliximab scintigraphy. Planar imagings of joints were recorded 10 min, 3 hrs and 24 hrs after i.v. injection of a mean of 617 MBq (range: 439-847) 99mTc-infliximab. The scintigraphic results were compared with clinical parameters (c reacting protein, joint swelling), MRI and/or sonography of affected joints. Results: 99mTc-Infliximab-scintigraphy showed TNFα expression in 6/10 patients with either rheumatoid arthritis or psoriatic arthritis. Both patients with gegenerative arthrosis with no clinical signs and radiological evidence of severe inflammation showed true negative scans. No side effects were reported by patients. Conclusions: The first preliminary results indicate that 99mTc-infliximab-scintigraphy may be a promissing tool for the selection of patients with inflammatory rheumatoid or psoriatic arthritis who may benefit from tratment with infliximab (Remicade®).