Quantification of synovitis in Rheumatoid Arthritis: Do we really need quantitative measurement of contrast-enhanced ultrasound?

Abstract Objective The quantification of synovitis is of great significance for adequate therapy management and follow-up in patients with Rheumatoid Arthritis (RA). The purpose of this study was to validate a semi-quantitative Power Doppler (PD) scoring system by comparing the PD scores to the objective measurement of the synovial inflammation using dynamic contrast-enhanced Pulse-Inversion Harmonic Imaging (PIHI). Materials and methods In 27 patients with RA, two radiologists performed semi-quantitative scoring of a PD examination, using a four-point scale from 0 to 3, in the metacarpophalangeal joints, proximal interphalangeal joints, and the wrists. The scores were compared to the area under the time-echo intensity curves obtained by contrast-enhanced PIHI examination. The interobserver agreement for PD scoring was evaluated using the Cohen's kappa test. Results Preliminary results showed that the area under the curve of dynamic measurements of PIHI tended to correlate with PD scores. The interobserver agreement for PD scoring was good ( κ  = 0.768). Discussion Based on comparisons with dynamic contrast-enhanced PIHI, semi-quantitative PD scoring might meet the criteria for a reliable, reproducible, and practical scoring system. Although further studies that would include a larger study population are required, our preliminary results show that PIHI may not provide a real benefit for quantification of synovitis in day-to-day practice.