Selected Factors Affecting Active Thermographic Measurement of Human Response to Cold Stress in RA Patient

Passive thermographic measurement is susceptible to multiple factors. However, there are not many evidences of how these factors impact the measurement of human hand skin temperature evolution after cold stress inducement, especially in patients with inflammatory lesions. The study aimed at the analysis of the variability factors in: heat source, environment conditions including material designed for placing hand, blood circulation, blood pressure and their effect on the hand infrared image of RA patients. Thermal image sequences were collected for 10 RA patients. The procedure consisted of hand immersion in ice-water for 5 seconds and 3-minute recording of temperature evolution for left and right hand, separately. Impact of the following factors was included in the analysis: heat source, material designed for placing hand, blood circulation. The plane, which is heated by the heat of the hands, emits radiation with similar intensity like the hand itself. During the process of hand warming, we observe gradual changes in the image of superficial veins. Blood vessels should be treated as an element of hand texture. The glow around the hand is a serious difficulty in the analysis. Development of dedicated algorithms is necessary.