George A. W. Bruyn

Ultrasound in medicine has a history arbitrarily going back to the days when a modified custom-built metal flaw detector was used in post-War Glasgow to diagnose abdominal masses. Spanning a period of 30 years, the article describes the coming of age of ultrasound within the field of rheumatology. This historical paper highlights collaborative research focusing on validation and standardization of the imaging modality. In addition, the work of several persons who have played a key role in the development of ultrasound in the field of rheumatology is emphasized. In real time and at the point of care, ultrasound can demonstrate where inflammation is present, thereby giving doctors and patients a better idea of why and where pain and stiffness originate. In retrospect, we may conclude that ultrasound has profoundly changed the practice of clinical rheumatology.

Objectives The main objective was to generate a GLobal OMERACT Ultrasound DActylitis Score (GLOUDAS) in psoriatic arthritis and to test its reliability. To this end, we assessed the validity, feasibility and applicability of ultrasound assessment of finger entheses to incorporate them into the scoring system. Methods The study consisted of a stepwise process. First, in cadaveric specimens, we identified enthesis sites of the fingers by ultrasound and gross anatomy, and then verified presence of entheseal tissue in histological samples. We then selected the entheses to be incorporated into a dactylitis scoring system through a Delphi consensus process among international experts. Next, we established and defined the ultrasound components of dactylitis and their scoring systems using Delphi methodology. Finally, we tested the interobserver and intraobserver reliability of the consensus- based scoring systemin patients with psoriatic dactylitis. Results 32 entheses were identified in cadaveric fingers. The presence of entheseal tissues was confirmed in all cadaveric samples. Of these, following the consensus process, 12 entheses were selected for inclusion in GLOUDAS. Ultrasound components of GLOUDAS agreed on through the Delphi process were synovitis, tenosynovitis, enthesitis, subcutaneous tissue inflammation and periextensor tendon inflammation. The scoring system for each component was also agreed on. Interobserver reliability was fair to good (κ 0.39–0.71) and intraobserver reliability good to excellent (κ 0.80–0.88) for dactylitis components. Interobserver and intraobserver agreement for the total B-mode and Doppler mode scores (sum of the scores of the individual abnormalities) were excellent (interobserver intraclass correlation coefficient (ICC) 0.98 for B-mode and 0.99 for Doppler mode; intraobserver ICC 0.98 for both modes). Conclusions We have produced a consensus-driven ultrasound dactylitis scoring system that has shown acceptable interobserver reliability and excellent intraobserver reliability. Through anatomical knowledge, small entheses of the fingers were identified and histologically validated.