Objectives: To investigate the inter/intra-reliability of ultrasound (US) muscle echogenicity in patients with rheumatic diseases.
Methods: Forty-two rheumatologists and 2 radiologists from 13 countries were asked to assess US muscle echogenicity of quadriceps muscle in 80 static images and 20 clips from 64 patients with different rheumatic diseases and 8 healthy subjects. Two visual scales were evaluated, a visual semi-quantitative scale (0-3) and a continuous quantitative measurement ("VAS echogenicity," 0-100). The same assessment was repeated to calculate intra-observer reliability. US muscle echogenicity was also calculated by an independent research assistant using a software for the analysis of scientific images (ImageJ). Inter and intra reliabilities were assessed by means of prevalence-adjusted bias-adjusted Kappa (PABAK), intraclass correlation coefficient (ICC) and correlations through Kendall's Tau and Pearson's Rho coefficients.
Results: The semi-quantitative scale showed a moderate inter-reliability [PABAK = 0.58 (0.57-0.59)] and a substantial intra-reliability [PABAK = 0.71 (0.68-0.73)]. The lowest inter and intra-reliability results were obtained for the intermediate grades (i.e., grade 1 and 2) of the semi-quantitative scale. "VAS echogenicity" showed a high reliability both in the inter-observer [ICC = 0.80 (0.75-0.85)] and intra-observer [ICC = 0.88 (0.88-0.89)] evaluations. A substantial association was found between the participants assessment of the semi-quantitative scale and "VAS echogenicity" [ICC = 0.52 (0.50-0.54)]. The correlation between these two visual scales and ImageJ analysis was high (tau = 0.76 and rho = 0.89, respectively).
Conclusion: The results of this large, multicenter study highlighted the overall good inter and intra-reliability of the US assessment of muscle echogenicity in patients with different rheumatic diseases.
Keywords: muscle echogenicity; musculoskeletal ultrasound; reliability; rheumatic diseases; sarcopenia.
Copyright © 2023 Di Matteo, Moscioni, Lommano, Cipolletta, Smerilli, Farah, Airoldi, Aydin, Becciolini, Bonfiglioli, Carotti, Carrara, Cazenave, Corradini, Cosatti, de Agustin, Destro Castaniti, Di Carlo, Di Donato, Di Geso, Elliott, Fodor, Francioso, Gabba, Hernández-Díaz, Horvath, Hurnakova, Jesus, Marin, Martire, Mashadi Mirza, Massarotti, Musca, Nair, Okano, Papalopoulos, Rosa, Rosemffet, Rovisco, Rozza, Salaffi, Scioscia, Scirè, Tamas, Tanimura, Ventura-Rios, Villota-Eraso, Villota, Voulgari, Vreju, Vukatana, Hereter, Zanetti, Grassi and Filippucci.