Technetium-99M in the Study of Rheumatic Joints

The accumulation of Tc-99m in knee and finger joints was studied in 41 rheumatic patients and 25 controls. The accumulation of the radioisotope was correlated with the intensity of active inflammation. Rheumatoid joints showed a stronger Tc-99m uptake than joints with osteoarthritis. There was some overlap, however, which limits the value of the method. The effect of local and systemic anti-rheumatic treatments could be followed with joint scanning. Radioactivity was also measured in the synovial fluid but this fraction of the Tc-99m was not large. The synovial fluid radioactivity tended to increase as the Tc-99m accumulation in the knee area decreased. Accumulation of Tc-99m in joints is regarded as principally due to the enhanced circulation in inflamed joint tissues.