Use of a Lucas–Kanade-Based Template Tracking Algorithm to Examine In Vivo Tendon Excursion during Voluntary Contraction Using Ultrasonography

Kiros Karamanidis,Artemis Travlou,Peter Krauss,Uwe Jaekel

doi:10.1016/j.ultrasmedbio.2016.02.019

Abstract

Ultrasound imaging can be used to study tendon movement during muscle contraction to estimate the tendon force–length relationship in vivo. Traditionally, such tendon displacement measurements are made manually (time consuming and subjective). Here we evaluated a Lucas–Kanade-based tracking algorithm with an optic flow extension that accounts for tendon movement characteristics between consecutive frames of an ultrasound image sequence. Eleven subjects performed 12 voluntary isometric plantar flexion contractions on a dynamometer. Simultaneously, the gastrocnemius medialis tendon was visualized via ultrasonography. Tendon displacement was estimated manually and by using two different automatic tracking algorithms. Maximal tendon elongation (manual: 17.9 ± 0.3 mm, automatic: 17.0 ± 0.3 mm) and tendon stiffness (209 ± 4 N/mm, 218 ± 5 N/mm) generated by the developed algorithm correlated with those obtained with the manual method (0.87 ≤ R ≤ 0.91), with no differences between methods. Our results suggest that optical flow methods can potentially be used for automatic estimation of tendon movement during contraction in ultrasound images, which is further improved by adding a penalty function.

Highlights

Analysis of human tendon length changes from ultrasound (US) images during maximal voluntary muscular contraction performed on a dynamometer is widely used, and has become highly popular, to assess the in vivo force-length-relationship of the tendon (Maganaris andPaul 2000; Arampatzis et al 2005; Reeves et al 2005)
Our results suggest that optical flow methods can potentially be used for automatic estimation of tendon movement during contraction in ultrasound images, which is further improved by adding a penalty function
We aimed to develop a Lucas-Kanade optical flow based template tracking algorithm (Lucas and Kanade 1981) that eliminates any unwanted jumps in the tracking of the gastrocnemius medialis tendon (GMtendon) elongation during maximal voluntary isometric ankle plantar flexion contractions (MVIP) on a dynamometer

Summary

Introduction

Analysis of human tendon length changes from ultrasound (US) images during maximal voluntary muscular contraction performed on a dynamometer is widely used, and has become highly popular, to assess the in vivo force-length-relationship of the tendon (Maganaris andPaul 2000; Arampatzis et al 2005; Reeves et al 2005). Analysis of human tendon length changes from ultrasound (US) images during maximal voluntary muscular contraction performed on a dynamometer is widely used, and has become highly popular, to assess the in vivo force-length-relationship of the tendon Tendon length changes by US during muscular contraction is usually estimated by choosing a tissue landmark (e.g. myotendinous junction) and manually digitizing that landmark frame by frame from rest until maximal tendon force (Arampatzis et al 2005; Arya and Kulig 2010). An automated method for tracking tendon length changes from US images during voluntary contractions on dynamometric devices would provide a time-efficient means for assessing tendon elongation and the force-length relationship. Once examined for its accuracy, such an analysis method would provide a time-efficient means for assessing human tendon stiffness in vivo, and could have significant applications in clinical and scientific settings

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Conclusion