Echo intensity reliability between two rectus femoris probe sites

Abstract

Introduction The ultrasound technique has been extensively used to measure echo intensity, with the goal of measuring muscle quality, muscle damage, or to detect neuromuscular disorders. However, it is not clear how reliable the technique is when comparing different days, raters, and analysts, or if the reliability is affected by the muscle site where the image is obtained from. The goal of this study was to compare the intra-rater, inter-rater, and inter-analyst reliability of ultrasound measurements obtained from two different sites at the rectus femoris muscle. Methods Muscle echo intensity was quantified from ultrasound images acquired at 50% [RF50] and at 70% [RF70] of the thigh length in 32 healthy subjects. Results Echo intensity values were higher ( p = 0.0001) at RF50 (61.08 ± 12.04) compared to RF70 (57.32 ± 12.58). Reliability was high in both RF50 and RF70 for all comparisons: intra-rater (ICC = 0.89 and 0.94), inter-rater (ICC = 0.89 and 0.89), and inter-analyst (ICC = 0.98 and 0.99), respectively. However, there were differences ( p < 0.05) between raters and analysts when obtaining/analyzing echo intensity values in both rectus femoris sites. Conclusions The differences in echo intensity values between positions suggest that rectus femoris's structure is not homogeneous, and therefore measurements from different muscle regions should not be used interchangeably. Both sites showed a high reliability, meaning that the measure is accurate if performed by the same experienced rater in different days, if performed by different experienced raters in the same day, and if analyzed by different well-trained analysts, regardless of the evaluated muscle site.

Ultrasound Imaging Analysis of the Lumbar Multifidus Muscle Echo Intensity: Intra-Rater and Inter-Rater Reliability of a Novice and an Experienced Rater

“…We are not aware of any other studies that have examined the effect of the rater's level of experience in acquiring LMM EI measurements. However, our findings are in accordance with other studies that have examined EI measures in other muscle groups [56][57][58].…”

“…The authors reported an inter-rater ICC of 0.897 and 0.837 for the abductor pollicis brevis and abductor digiti minimi muscle, respectively. Accordingly, it appears that even with minimal experience or training by the rater, the reliability of EI muscle measurements are good to excellent [56][57][58]. These findings are similar to our study, which showed good to excellent reliability between the novice raters and the experienced rater, except for Novice 1 for the right LMM, which revealed lower ICCs and a wider 95% CI.…”

“…The authors reported an inter-rater ICC of 0.95 and an SEM of 0.9 between a rater with six years of ultrasound experience and a rater with one year of experience. Rabello et al [57] investigated the inter-rater reliability of rectus femoris muscle EI measurements in 32 healthy participants (50% female) between a rater with four years of ultrasound experience and a rater with one year of experience. Ultrasound images were obtained at 50% of the rectus femoris belly length and at 70% of the rectus femoris belly length.…”

Exercise induced changes in echo intensity within the muscle: a brief review

“…Importantly, although the direction of change will likely be the same across a range of settings, the magnitude of change will likely be different. Probe sites should also be considered, as measurements from different muscle regions might result in different responses [79]. However, with respect to the impact of exercise, the important question would be "do different regions of the muscle result in different changes?"…”

Echo Intensity Reliability From Two Ultrasound Systems

“…This allows for controlling intervening variables and ascertaining whether changes in the participant's results are truly due to an adaptation and not to changes in the US system parameters. Reliability studies have been conducted to quantify the influence of moments, 21,22 raters, 23,24 transducer tilt, 25 muscle site, 24 image analysis technique, 26,27 and analysts 24,28 on the results, finding that reliability of EI measurements are high to very high. However, few studies have evaluated the influence of using different US systems on muscle EI values.…”