To evaluate the synovial blood flow in rheumatoid arthritis (RA) patients with subclinical synovitis by contrast-enhanced ultrasound (CEUS), and to evaluate the value of CEUS-related parameters in evaluating the progression of subclinical synovitis in these patients.

A total of 87 patients with RA and subclinical synovitis admitted to the Affiliated Hospital of Inner Mongolia Medical University from October 2019 to December 2023 were collected. The patients were included for wrist CEUS examination, and quantitative parameters of CEUS were obtained: arrival time (AT), time to peak (TTP), peak intensity (PI), Gard gradient, and area under the time-intensity curve (TIC). The synovial blood flow was graded. Patients were followed up at 3, 6, and 12 months after treatment. Correlation analysis was conducted between the quantitative indexes of CEUS and the Disease Activity Score (DAS) 28, and the DAS28 was used as the criterion to judge whether the disease was aggravated. The patients were divided into 33 cases with disease exacerbation and 54 without. Univariate and multivariate Logistic regression analyses were performed to identify the independent risk factors for predicting the exacerbation of subclinical synovitis in RA, and receiver operating characteristic (ROC) curve analysis was performed to evaluate the predictive efficacy of related parameters for the exacerbation of subclinical synovitis.

Among the 87 patients included, 36 had grade 1 synovial blood flow, 29 had grade 2, and 22 had grade 3. Synovial blood flow grade, area under the TIC, and PI had a significant correlation with DAS28 at 3 months (r = 0.659, 0.711, 0.777, P<0.05), 6 months (r = 0.651, 0.707, and 0.757, respectively, P<0.05) and 12 months (r = 0.640, 0.688, and 0.721, respectively, P<0.05) after treatment. Multivariate Logistic regression analysis showed that the area under the TIC (odds ratio [OR]=1.023, 95% confidence interval [CI]: 1.003~1.047) and PI (OR = 1.564, 95%CI: 1.031~2.267) were independent risk factors for predicting the exacerbation of subclinical synovitis in patients with RA. The area under the ROC curve values of the area under the TIC and PI for predicting disease exacerbation were 0.909 and 0.692, respectively, and their difference was statistically significant (P<0.05).

There is a good correlation between CEUS quantitative indexes and DAS28, and the area under the TIC and PI have good application value in predicting the progression of subclinical synovitis in RA patients, which can provide an objective basis for the formulation of clinical treatment plan, efficacy evaluation, and disease monitoring.