99Tcm-labelled leucocyte imaging in active rheumatoid arthritis.

A simplified technique of labelling leucocytes with technetium-99m is described and applied to patients with active rheumatoid arthritis. The clinically active and less active knees in seven patients were imaged and the uptake of labelled leucocytes was measured. The measurements were repeated after local steroid injection into nine painful knees. A 50-80% reduction in leucocyte uptake localized to the region of the synovium was demonstrated in the eight knees which showed clinical responses and a rise of 8% in the non-responder. There was a variable response in the knees that were not injected. 99Tcm leucocyte imaging in rheumatoid arthritis is able to assess objectively joint inflammation and its response to treatment.