Evaluation of rheumatoid arthritis in small animal model using Thermal imaging

Rheumatoid arthritis (RA) is a chronic autoimmune disease which affects the hand joints, wrist, feet, knee, shoulders and other regions of the body. Animal model of RA is used to evaluate the inflammatory condition and for diagnosing the disease. Although various imaging modalities like x-rays, CT and MRI are available in evaluation and diagnosing the disease, those modalities are expensive and have radiation effects. Thermal imaging plays a vital role in evaluation and monitoring the inflammation in rheumatoid arthritis Thermal imaging is a non invasive method for detecting the pathogenesis of the disease compared to other diagnostic methods. The objectives of this study were: i) to measure the changes in skin temperature of induced RA limbs when comparing to normal; ii) to find out the efficacy of an automated segmentation of induced RA limbs using the following image processing techniques: a) Robert edge detector; b) Canny edge detector; and c) Adaptive thresholding technique. 0.2ml of mixture of freunds complete adjuvant (FCA) mixed with a phosphate buffer saline at 1∶1 was injected at right side both hind- and fore- limbs of the Wistar rats (n=10), whereas normal saline was injected at left side both hind- and fore- limbs of the rats. After having induced RA in the limbs of the rats (after 30 days), thermal image of each rat was obtained under standard conditions. The measured mean temperature (°C) was found to be higher by 1.8% and 2.0% respectively at RA hind and fore limbs respectively than in the corresponding normal limbs. Adaptive thresholding method was found to be the best of method studied in segmenting the induced RA limb of the rat.