Ultrasound remission can predict future good structural outcome in collagen-induced arthritis rats

Regarding the persistence of subclinical synovitis, the concept of ultrasound remission has been proposed in addition to clinical remission. The present study aims to explore whether ultrasound remission has predictive value and ultrasound remission at which time point has predictive value for good structural outcome. Collagen-induced arthritis (CIA) was induced in 32 rats by immunizing with bovine type II collagen. Twenty-four CIA rats were treated with rhTNFR:Fc, and 8 rats were left untreated. Ultrasonography was performed to assess synovial hypertrophy, power Doppler (PD) signal, and bone erosion of the ankle joints of both hindpaws every week following the booster immunization. In the treated group, the scores for synovial hypertrophy, PD signal and bone erosions decreased from baseline to the end. Synovial hypertrophy, PD signal, and bone erosion at baseline were not significantly associated with good structural outcome. Ultrasound remission from 4 to 6 weeks after treatment was significantly associated with good outcome and had the highest area under the curve, sensitivity, specificity, and positive and negative predictive values. Therefore, we conclude that ultrasound remission from 4 to 6 weeks after treatment has a high value for predicting good structural outcome in CIA rats.