Protocol refinement and inter- and intra-rater reliability assessment of ultrasound-based measurements of hamstring architecture, and echo intensity, and intra-rater reliability of shear wave elastography

Abstract

Objectives

The increase in hamstring injuries highlights gaps in current understanding and prevention strategies. Hamstring architecture, quality, and mechanical properties influence force production, offering key insights into muscle health and function. This study aims to refine a standardized protocol for hamstring image acquisition and digitization and to assess inter- and intra-rater reliability of measurements like fascicle length, pennation angle, muscle thickness, cross-sectional area, echo intensity, and shear wave elastography.

Methods

This study had two phases: pilot and protocol refinement and intra- and inter-rater reliability of image digitization of fascicle length, pennation angle, muscle thickness, cross-sectional area, and echo intensity and intra-rater reliability of shear wave elastography using intra-class correlation coefficient.

Results

This study developed and refined a hamstring image acquisition and digitization protocol, focusing on architecture, quality, and stiffness along its length at rest and during isometric contraction. Using Image J, intra-rater reliability for digitizing fascicle length, pennation angle, muscle thickness, cross-sectional area, and echo intensity was excellent. Inter-rater reliability ranged from moderate to excellent across all variables. Shear wave elastography showed moderate to excellent intra-rater reliability, with higher consistency during contraction than rest.

Conclusion

The authors refined a standardized protocol for ultrasound imaging of hamstring architecture, quality, and stiffness, as well as digitization of fascicle length, pennation angle, muscle thickness, cross-sectional area, and echo intensity at rest and during isometric contraction using ImageJ. The protocol demonstrated moderate to excellent intra- and inter-rater reliability, with image markings further enhancing measurement consistency.