Reliability of muscle thickness and echo intensity measurements of the quadriceps: A novice examiner

Abstract

Introduction: This study aimed to investigate the reliability of muscle thickness (MT) and echo intensity (EI) of the quadriceps muscles using ultrasound imaging for a novice examiner.

Methods: Sixteen healthy adult women were included in the study, and images of the rectus femoris, vastus intermedius, vastus lateralis, and vastus medialis were obtained on the same day and after one week by an examiner who had not performed an experiment on the measurement of ultrasound imaging. The measurers who analyzed all images were completely blind to the subject's name and date and order of measurements. Intraclass correlation coefficients (ICCs) were used as relative within-day and between-day reliability of measurement. Absolute reliability was based on Bland-Altman analysis, standard error of measurement, and minimum detectable change.

Results: The ICCs ranged from 0.76 to 0.95. As the results of the Bland-Altman analysis, all MTs and EIs included 0 in the 95% confidence interval of the mean difference.

Discussion: Our results suggest that quadriceps ultrasound images have high reliability for MT and EI for all muscles. There were no systematic errors in both MT and EI.

Conclusion: It might indicate that even novice examiners could obtain MT and EI measurements without systematic error after a few hours of practice.

Keywords: Echo intensity; Muscle thickness; Quadriceps; Reliability; Ultrasound.