Definitions and online reliability assessment of elementary ultrasound lesions in Takayasu arteritis: a study from...

Reliable tools for monitoring disease activity in Takayasu arteritis (TAK) are lacking, and ultrasonography (US) may represent a valuable option. This study aimed to: 1) develop consensus-based definitions for key US lesions in TAK; 2) identify the relevant arterial segments to include in an US-based score; 3) assess inter- and intra-rater reliability of the definitions in a web-based image analysis and scoring exercise.

A Delphi survey was conducted among members of the OMERACT Ultrasound Working Group to agree upon the definitions of key elementary US lesions and arterial segments to be included. A subsequent web-based reliability exercise included US images from TAK patients and healthy controls depicting the consensual lesions. Experts scored each image in two separate rounds. Inter-rater and intra-rater reliability were assessed using Fleiss' and Cohen's kappa (κ), respectively.

Three Delphi rounds were completed with 47, 46, and 43 experts respectively. Consensus was reached on three lesions ('macaroni sign', stenosis, occlusion) and seven arterial segments (bilateral common carotid, subclavian, axillary arteries, abdominal aorta). Forty-five experts completed the reliability exercise. Inter-rater reliability was moderate to good (κ = 0.47-0.64), with the highest agreement for the 'macaroni sign' in the carotid artery (κ = 0.73). Intra-rater reliability was good (κ = 0.72-0.79), with lower agreement for stenosis and occlusion in the abdominal aorta.

This OMERACT initiative established consensus-based definitions for US lesions in TAK and identified key relevant arterial segments, providing a reliable basis for the development of a standardized US composite score.