Quantitation of thermography in arthritis using multi-isothermal analysis. I. The thermographic index.

Thermography can be used for the assessment of joint involvement in inflammatory arthritis. Modem thermographic apparatus allows temperature to be measured to within 0-2°C. and simultaneously records the areas involved. It has been demonstrated that thermographic changes in skin temperature over areas of chronic inflammation properly reflect changes in other chemical and cellular processes in rheumatoid arthritis (Ring and Collins, 1970; Collins and Cosh, 1970). The method also agrees with the findings of joint scans after technetium injection (Cosh, Lindsay, Rhys-Davies, and Ring, 1970) and correlates with the intra-articular temperature taken by thermistor probe (Lloyd-Williams, Ring, and Cosh, 1970). Recently Pinder and Ring (1974) have shown that thermographic recordings accurately locate areas of inflamed synovial tissue as shown at synovectomy. The effect of anti-inflammatory compounds on joint inflammation in animals has been quantitated using radiometry (Collins and Ring, 1972). Thermography provides more information about the distribution of temperature. We wish to report a method for the quantitative measurement of joint inflammation in man, using thermography.