Objective: The aim of this study was to evaluate the progression of arthritis in a complete Freund's adjuvant (CFA)-induced Wistar rat model and to monitor inflammatory arthritis activity using thermal imaging compared with histopathology.
Methodology: Fifteen adult male Wistar rats were studied in an adjuvant-induced arthritis model by the injection of complete Freund's adjuvant in the right hind limb and right forelimb, respectively, with the left limbs used as controls. Thermal image analysis based on skin temperature measurement, radiographic analysis based on erosion, limb circumference measurement, and histopathological evaluation were performed.
Results: The average skin temperature difference on the arthritis-induced side and control for both the forelimb and hind limb were found to be 1.09 °C and 0.98 °C, respectively. Pearson correlation analysis revealed that skin surface temperature was positively correlated with the arthritis severity score (forelimb: r = 0.64, hind limb: r = 0.66, p < 0.05).A significant correlation also existed between thermal imaging temperature and visual scoring of X-ray (forelimb: r = 0.56, hind limb: r = 0.67, p < 0.05).
Conclusion: Thermal imaging measurements correlated with arthritis severity score, radiological score, and ankle diameters. Hence, thermography could be used to diagnose and analyze inflammatory activity of arthritis at the preclinical stage.