Abstract: Objective To explore an evaluation model for the therapeutic effect of rheumatoid arthritis(RA) based on the image characteristics and quantitative parameters of magnetic resonance imaging(MRI). 
Methods A total of 120 patients with RA were selected as the research subjects, all of whom were treated with recombinant human tumor necrosis factor receptor antibody fusion protein combined with methotrexate, and the efficacy was evaluated at 3 months after treatment. They were divided into an effective group(n=94) and an ineffective group(n=26) according to the efficacy. MRI imaging characteristics(bone erosion, bone marrow edema), quantitative parameters ［volume transfer constant(Ktrans), fractional plasma volume(Vp), flow perfusion parameters(F), vascular permeability surface(PS)］ and serum markers［cyclic citrullinated peptide(CCP) antibodies, rheumatoid factor(RF)］ levels were compared between two groups before and after treatment. The relationship between MRI image characteristics, quantitative parameters and serum markers was analyzed. The value of MRI imaging characteristics and quantitative parameters on the assessment of efficacy was evaluated. 
Results At 3 months after treatment, the scores of bone erosion, bone marrow edema, Ktrans, Vp, F and PS on MRI in both groups were lower than those before treatment, and in the effective group were lower than those in the ineffective group(P＜0.05). The levels of serum CCP antibody and RF were lower than those before treatment, and lower in the effective group than in the ineffective group(P＜0.05). Bone erosion, bone marrow edema score, Ktrans, Vp, F, and PS differences on MRI were positively correlated with serum CCP antibody and RF level before and at 3 months after treatment(P＜0.05). Logistic regression analysis showed that MRI bone erosion, bone marrow edema score, Ktrans, Vp, F, and PS difference were independent influencing factors of RA efficacy before and at 3 months after treatment(P＜0.05). Logistic regression model equation was as follows: 3.175-1.058×difference of bone erosion score -0.842×score difference of bone marrow edema -0.894×Ktrans difference value -0.606×Vp difference value -0.952×F difference -1.014×PS difference. The AUC of bone erosion, bone marrow edema score, Ktrans, Vp, F, and PS difference on MRI alone in evaluating efficacy was 0.816, 0.719, 0.769, 0.803, 0.828, and 0.778, respectively; the AUC of combined evaluation was 0.924(95%CI: 0.862-0.965), sensitivity was 88.46%, and specificity was 87.23%, which were superior to the evaluation value of each index alone. 
Conclusion The evaluation model constructed by imaging characteristics of bone erosion, bone marrow edema, Ktrans, Vp, F, PS and other quantitative parameters on MRI can be used as an important auxiliary way to evaluate the efficacy of RA, which can provide more comprehensive and reliable data support for accurate clinical evaluation of efficacy.

Key words: arthritis, rheumatoid, magnetic resonance imaging, imaging characteristics