A Reliable Method for Quantification of Tendon Structure Using B-Mode Ultrasound

Abstract

Structure is an important clinical marker of tendon health; however, current standards use qualitative scores that are not strongly reliable. Therefore, the purpose of this study was to establish the reliability of an image-processing technique that quantifies tendon collagen structure using B-mode ultrasound images. Longitudinal images of the Achilles tendon were collected in 12 healthy young adults, and intra- and inter-rater reliability was assessed over multiple image selections and multiple days. Intraclass correlation coefficients were strong (r ≥ 0.71) for all comparisons. These findings demonstrate that quantitative assessments of tendon structure using B-mode ultrasound are reliable.

Keywords: basic science (tissue characterization); collagen; organization; quantitative; reliability; sports medicine/orthopedics; tendon structure.

© 2018 by the American Institute of Ultrasound in Medicine.

Figures

Figure 1.

Ultrasound evaluations of continuous longitudinal imaging of the tendon were performed by a single investigator (O1). Single images of the tendon were independently selected by two investigators (O1 and O2). Regions of interest from each image were independently selected by three investigators (O1, O2, and O3) on back to back days. These selections were analyzed to generate the quantitative measure of collagen organization: circular standard deviation (CSD). Intra- and interrater reliability was calculated using a two-way mixed-effects intraclass correlation (ICC) model.

Figure 2.

Rectangular regions of interest that encompassed as much of the free Achilles tendon as possible were independently selected by three investigators (left). Selections were processed computationally to identify the fascicles of the tendon (middle). Collagen fascicle alignment was calculated based on the deviation from the mean direction of all identified fascicles, termed the circular standard deviation (CSD).