To assess the clinical application value of ultramicroangiography (UMA) in the evaluation of proliferative blood vessels in rheumatoid arthritis (RA) patients and the clinical significance of penetrating blood flow signals in bone erosion defects on UMA.

Power Doppler ultrasound (PDUS) and UMA were performed on the wrist joint, 2-3 metacarpophalangeal joints, and 2-3 proximal interphalangeal joints in 29 patients with RA at Peking Union Medical College from May 2020 to April 2021, and synovial blood flow signals and semi-quantitative score were recorded. Wilcoxon's sign rank test was used to compare the differences of PDUS-sum and UMA-sum in the above joints. Spearman's correlation was used to analyze their correlation with C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), DAS28(ESR), DAS28(CRP), simplified disease activity index (SDAI), clinical disease activity index (CDAI), swollen joint count, tender joint count, visual analog scale (VAS), patient's global assessment, and evaluator's global assessment. The patients were divided into either a UMA-sign (+) group or a UMA-sign (-) group according to whether UMA-sign appeared, and the differences in the above disease activity-related indicators between the two groups were analyzed by the Mann-Whitney U test.

In the 29 RA patients included, the display rates of synovial blood flow signals were 21.38% and 27.59% in PDUS and UMA mode, respectively. There was a statistical difference between PDUS-sum and UMA-sum (Z=3.472, P=0.001). The degree of correlation between UMA-sum and disease activity-related indicators was higher than that between PDUS-sum and disease activity-related indicators; the correlation between PDUS-sum and CRP was the highest (r=0.536, P=0.003), while the correlation between UMA-sum and the swollen joint count was the highest (r=0.664, P=0.000). The disease activity-related indicators CRP, ESR, DAS28(ESR), DAS28(CRP), SDAI, CDAI, swollen joint count, tender joint count, VAS, patient's global assessment, evaluator's global assessment, PDUS-sum, and UMA-sum were significantly higher in the UMA-sign (+) group than in the UMA-sign (-) group (P＜0.05).

UMA is more sensitive in detecting synovial proliferative blood vessels when compared with PDUS, and UMA-sum has potential clinical significance in evaluating disease activity in RA patients. The appearance of UMA-sign in RA patients may indicate higher disease activity.