Background/Purpose: Usefulness of quantitative assessment of synovial vascularity in ultrasound (US) imaging in patients with active RA and PsA (peripheral arthritis). Additionally the assessment of vascularity index (INDEX%) dependency on immunological markers such as rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPA) were assessed.The last aim of the study was to examine whether patients with high active peripheral PsA differ in the severity of synovial congestion from patients with high RA activity.

Methods: A total of n=80 patients were included into the study, n=60 with RA and n=20 PsA. Majority of them (for both group) were female (n=53.66.25%). Laboratory variables were assessed: RF (IU/ML units), ACPA (U/ML), ESR (mm/hour) and C-reactive protein (CRP;MG/L); disease activity were assessed by DAS 28(ESR) and simplified disease activity score (SDAI). The power doppler US (PDUS) was performed with assessment of a) the degree of the synovial membrane vascularization (from 0 to 4 grade); the following scores were used in the assessment: 0- no signs of synovial flow, 1- isolated signals in hypertrophied synovium, 2-vessels occupy less than 50% of hypertrophied membrane area synovitis, 3- inflammation affects over 50% of the examined area; b) vascularity index measured by PDUS index (INDEX%) in the ROI (region of interest) frame (figure 1). All patients underwent examination using the same US machine and by the same specialist in radiology and imaging diagnostics.

Results: Disease activity for RA and PsA patients was between 4.8- 8.3 with DAS28 and 23-183 with SDAI. The hypothesis of a positive correlation between the concentration of ACPA and INDEX% in RA group was confirmed however it was a week positivity(r=0.26) but such correlation between RF and INDEX% was not confirmed (r=0.03). ESR, CRP, DAS 28(ESR) and SDAI did not correlate significantly with the value of INDEX%. What was expected the strong positivity (r=0.56) was between SDAI and DAS28 results. Interestingly there was no correlation between DAS 28, SDAI and INDEX %, probably because all of patients from both groups had high disease activity.

Conclusion: Positive correlation between the concentration of ACPA and INDEX% value indicating that ACPA may be a prognostic factor for vascularization of the synovial membrane in patients with RA. No such correlation was confirmed for RF. Taken together obtained results pointed to ACPA as more important for synovial inflammatory activity in RA. Vascularity of synovial membrane assesed by INDEX %compared between RA and PsA group was equally high, despite the difference in RF and ACPA indicating that the presence of other cytokines is more involved in the development of synovial inflammation in PsA. The quantitative US assessment of synovial vascularity is a useful tool in comparative studies and may have a significant advantage over a qualitative study after expanding the study groups with different degrees of inflammatory activity in the synovium.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/quantitative-assessment-of-synovial-vascularity-using-power-doppler-index-in-rheumatoid-arthritis-and-psoriatic-arthritis-patients-with-high-disease-activity/