How much different is the semi-quantification of synovitis according to the ultrasound system and the blood flow detection technology?

Aim: To compare synovial blood flow scoring between different technologies and ultrasound (US) systems in active and inactive rheumatoid arthritis (RA). Material and methods. Fifty-nine RA patients underwent B-mode, power Doppler (PD), colour Doppler (CD), B-Flow and High-Resolution (High-Res) PDI assessments of 6 joints with two US systems at two European centres. Each joint was semi-quantitatively scored for all ultrasound parameters. PD, CD and High-Res PDI synovial signal was also quantitatively scored. Results. Correlations between the total score of SH with system 1 and 2 were very high (≥ 0.90, p<0.0001). Baseline correlations between systems for PD and CD total scores were moderate to very high (0.44-0.96, p<0.05). At baseline, there were no significant differences between ultrasound systems for PD or CD semiquantitative-based total scores in active or inactive patients (p>0,05). B-Flow and High-Res total scores were significantly lower than PD or CD total scores (p<0.05). Conclusion. A high-end and an entry-level US system were interchangeable for scoring SH and showed similar sensitivity and responsiveness in scoring synovial blood flow by PD and CD but not interchangeability. B-Flow and High-Res PDI were responsive, but they showed different sensitivity to detect synovial blood flow compared to conventional Doppler.