The Reliability of using Ultrasound for the detection of hypoechogenicity of enthesitis in patients with spondyloarthropathies

Abstract

Abstract: Objectives: To determine the interobserver and intraobserver reliability of grading hypoechogenicity within ultrasound images of Achilles tendon entheses of patients with SpA. The second objective to compare the mean grey values of pixels within the entheses area of the Achilles tendon using ImageJ software with the expert semiquantitative scoring of hypoechogenicity of the same ultrasound images to determine the level of agreement between approaches. Methods: Six participants (rheumatologists and sonographer) scored the hypoechogenicity in 100 static images of Achilles tendon enthesis of patients with SpA. Two scoring systems were used; semi-quantitative score system and binary score system. The intraclass correlation coefficient (ICC) and Cohen's kappa were used to assess interobserver reliability. The ImageJ software was used to measure the mean grey values (MGV) of the pixels within the enthesis. 2 Results: The interobserver reliability was good for using the semi-quantitative score (ICC 0.780 (95% CI 0.691–0.849)) and moderate for the binary score (ICC 0.632 (95% CI 0.490-0.745)). The agreement between the consensus score (CS) and the six raters was poor or fair, except for one rater that has a moderate agreement with the CS. There was no match between the results from the quantitative score of the pixels MGV and the expert semi-quantitative score. Conclusion: The validity of the results from the reliability exercise in this study was affected by different factors related to the participants, images or environments. The accurate measurement of the pixel MGV was limited by the image artefacts and different machine settings