Technetium-99m human polyclonal immunoglobulin G studies and conventional bone scans to detect active joint inflammation in chronic rheumatoid arthritis

Abstract

Rheumatoid arthritis is a chronic polyarthritis in which active inflammed joints coexist with joints in remission. We performed bone scans (^99mTc-DPD) and ^99mTc human polyclonal immunoglobulin G scans (^99mTc-IgG) in 18 patients with rheumatoid arthritis to assess the uptake in actively inflamed joints and in joints in which remission after inflammation had occurred. A quantitative analysis of tracer uptake in each joint was performed on both scans. In 123 joints without current active inflammation, an increased ^99mTc-DPD uptake was observed (2.31 ± 1.27), whereas no ^99mTc-IgG uptake was noted (1.18±0.32). Some 78 joints with mild pain or swelling exhibited increased ^99mTc-DPD uptake (2.48 ± 1.14) and increased ^99mTc-IgG uptake (1.76 ± 0.50; P <0.001), while 21 joints with moderate to severe pain or swelling exhibited increased ^99mTc-DPD uptake (2.39±0.93) and increased ^99mTc-IgG uptake (1.79±0.51; P <0.001). In conclusion, ^99mTc-IgG scans distinguish between joints with and without active inflammation in chronic rheumatoid arthritis, whereas bone scans do not. Thus, ^99mTc-IgG scans may be useful in identifying joints with current active inflammation in rheumatoid arthritis.