Background: Superb Microvascular Imaging (SMI) is a novel ultrasound (US) doppler technology that expands the visible range of low microvascular blood flow improving the sensitivity of US for joint inflammation in contrast to conventional power Doppler (CPD). To date, limited studies have been published comparing SMI with CPD in Juvenile idiopathic arthritis (JIA).

Objectives: To investigate the sensitivity of SMI vs CPD in the US-evaluation of synovial inflammation in patients with JIA using the OMERACT score.

Methods: JIA patients with clinically determined knee synovitis who consented to the study were investigated using B-Mode (BM) and Doppler US with SMI and CPD. US and probe settings were standardised and six standard views saved for each knee joint (suprapatellar longitudinal and transverse, parapatellar medial and lateral and longitudinal medial and lateral). A semi-quantitative grading scale from 0 (no blood flow signal within the synovial membrane) to 3 (blood flow signal in more than one-half of the synovial membrane) defined by OMERACT was used to score the intra-synovial blood flow indicated by SMI and CPD. The BM findings were also graded 0-3, depending on the extent of synovial effusion or synovial hypertrophy. As 6 individual views per knee joint were evaluated, the highest individual CPD and SMI grade per knee were also compared (Table 1), as well as the individual images. Within this study, we additionally tested a novel US-score using the different Doppler techniques, calculated using the highest single BM grade (max.3, as per OMERACT score) plus the highest single CPD or SMI grade (max.3) for each patient, with a maximum possible score of 6.

Results: 144 images (72 US views with each technique, 12 knees with synovitis) were analysed. The mean BM grade was 1.8. SMI grading was significant higher than CPD (mean SMI score 1.1 vs mean CPD score 0.3 (p < 0.01) when analysing all scans. The mean ultrasound score using SMI+BM was also significant higher than when calculated using CPD+BM (p < 0,01).

Conclusion: SMI Doppler seems to be a highly sensitive Doppler Mode for the detection of synovial hypervascularity in knee joints of JIA patients. Qualitative analysis of images indicated better definition of synovial vascular microarchitecture with SMI compared to CPD. SMI could therefore represent a more precise imaging tool for diagnosing and monitoring intrasynovial hypervascularization.

REFERENCES: NIL.

Acknowledgements: NIL.

Disclosure of Interests: None declared.