MEASUREMENT OF RADIOGRAPHIC CHANGES IN ADJUVANT-INDUCED ARTHRITIS IN RATS BY QUANTITATIVE IMAGE-ANALYSIS

Objective, To apply quantitative analytical methods to the evaluation of radiographic images in experimental arthritis, Methods. Adjuvant wa s used to induce arthritis in rats. Arthritis progression was followed by conventional methods, In addition, digitized images of radiographs of the calcaneus were examined for changes in the mean and in the dis tribution pattern of gray values. Periosteal new bone formation was me asured as an increase in image area of the calcaneus. Results. Signifi cant changes in the gray value profile and increases in periosteal bon e formation occurred in arthritic rats. More extensive changes occurre d in Lewis rats than in Sprague-Dawley rats. Analysis of serial radiog raphs revealed an initial decrease in the density of juxtaarticular bo ne, followed by progressive increases in gray value variation due to c oncurrent bone loss and bone formation, Eventually, bone formation in arthritic rats resulted in increased gray values above those in nonart hritic rats, Conclusion, Image analysis represents a sensitive, quanti tative method for detecting radiographic changes in experimental arthr itis,