Uptake of Sr-85 in joints damaged by rheumatoid arthritis.

Abstract

A. Rekonen, Central Hospital, Jyv~skyl~i, Finland, and T. Holopalnen, Central Hospltal, Kuopio, Finland. The distribution and behavior of radioactive Strontlum-85 can be followed by external counting of radiation, and this isotope is thus suitable for studying local disturbances of the calcium metabolism of bones. Such local bone changes occur in rheumatoid arthritis already in the initial phase of the disease and the authors performed strontium uptake measurements in patients with joints damaged by rheumatoid arthritis. The external measurements were performed a week after an intravenous injection of 20 uCi of Sr-85 and the results are as follows: The uptake of strontium is more pronounced in a joint damaged by rheumatoid arthritis than in a symptomless joint. The increase in the strontium uptake is correlated with the severity of the damage. In some cases an increased accumulation was observed prior to roentgenologic demonstration of bone and cartilage changes. There was no correlation between the St-uptake and the inflammatory activity. Measurements of tissue specimens indicate that the bone plays the greatest role in Stuptake although there is a manifest accumulation of strontium in the cartilage and synovium as well. Using Technetium-99m as tracer it is possible to measure the inflammatory activffy in joints with rheumatoid arthritis. In Fig. 1 it is demonstrated the technetium accumulation in an inflamed knee (right). Fig, 2 shows the strontium uptake in this same knee. Fig. I. Accumulation of Tc-99m in an inflamed knee (right). Fig. 2. Same knees as in figure I, scanned with Sr-85.