0
Technical Briefs

Tendon Strain Measurements With Dynamic Ultrasound Images: Evaluation of Digital Image Correlation

[+] Author and Article Information
Gregory Okotie, Sarah Duenwald-Kuehl

Department of Orthopedics and Rehabilitation,Department of Biomedical Engineering,  University of Wisconsin-Madison, Madison, WI 53705

Hirohito Kobayashi

Department of Orthopedics and Rehabilitation,  University of Wisconsin-Madison, Madison, WI 53705

Mon-Ju Wu

Department of Orthopedics and Rehabilitation,Materials Science Program,  University of Wisconsin-Madison, Madison, WI 53705

Ray Vanderby1

Department of Orthopedics and Rehabilitation,Department of Biomedical Engineering,Materials Science Program,Room 5059, 1111 Highland Ave.,  University of Wisconsin-Madison, Madison, WI 53705vanderby@ortho.wisc.edu

1

Corresponding author.

J Biomech Eng 134(2), 024504 (Mar 19, 2012) (4 pages) doi:10.1115/1.4006116 History: Received January 31, 2012; Revised February 01, 2012; Posted February 21, 2012; Published March 14, 2012; Online March 19, 2012

Strain is an essential metric in tissue mechanics. Strains and strain distributions during functional loads can help identify damaged and pathologic regions as well as quantify functional compromise. Noninvasive strain measurement in vivo is difficult to perform. The goal of this in vitro study is to determine the efficacy of digital image correlation (DIC) methods to measure strain in B-mode ultrasound images. The Achilles tendons of eight male Wistar rats were removed and mechanically cycled between 0 and 1% strain. Three cine video images were captured for each specimen: (1) optical video for manual tracking of optical markers; (2) optical video for DIC tracking of optical surface markers; and (3) ultrasound video for DIC tracking of image texture within the tissue. All three imaging modalities were similarly able to measure tendon strain during cyclic testing. Manual/ImageJ-based strain values linearly correlated with DIC (optical marker)-based strain values for all eight tendons with a slope of 0.970. DIC (optical marker)-based strain values linearly correlated with DIC (ultrasound texture)-based strain values for all eight tendons with a slope of 1.003. Strain measurement using DIC was as accurate as manual image tracking methods, and DIC tracking was equally accurate when tracking ultrasound texture as when tracking optical markers. This study supports the use of DIC to calculate strains directly from the texture present in standard B-mode ultrasound images and supports the use of DIC for in vivo strain measurement using ultrasound images without additional markers, either artificially placed (for optical tracking) or anatomically in view (i.e., bony landmarks and/or muscle-tendon junctions).

FIGURES IN THIS ARTICLE
<>
Copyright © 2012 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Optical tracking results using ImageJ (open squares) and DIC (open circles). There is a strong correlation between values computed using manual (ImageJ) and DIC tracking of optical videos (R2 value of 0.955). Such a strong correlation demonstrates the ability of DIC to track and calculate strain measurements on optical videos of tissues as accurately as manual methods. These findings were similar in the eight tendons that were tracked; correlation shown in Fig. 2.

Grahic Jump Location
Figure 2

Linear correlation between strain values calculated manually (using ImageJ) and using DIC tracking methods, plotted with a 95% confidence interval. A strong correlation is shown, with mean intercept and slope of the eight tendons of 0.000 and 0.970, respectively.

Grahic Jump Location
Figure 3

DIC tracking results using optical video with markers and ultrasound videos demonstrating correlation (R2 value of 0.803). These findings were similar in all tested tendons. Such strong correlation demonstrates the ability of DIC to track and calculate strain measurements on ultrasound videos (using only tissue texture) as accurately as when using optical marker methods. Linear correlation is shown in Fig. 4.

Grahic Jump Location
Figure 4

Linear correlation between strain values calculated by DIC tracking of tendons using optical and ultrasound videos, plotted. The mean intercept and slope of the six tendons analyzed were 0.000 and 1.003, respectively.

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In