Use of a Lucas-Kanade-Based Template Tracking Algorithm to Examine In Vivo Tendon Excursion during Voluntary Contraction Using Ultrasonography.
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.
Institute of Movement and Sport Gerontology, German Sport University Cologne, Cologne, Germany; Institute of Biomechanics and Orthopaedics, German Sport University Cologne, Cologne, Germany. Electronic address: karamanidis@dshs-koeln.de.
Kiros
K
Karamanidis
Institute of Movement and Sport Gerontology, German Sport University Cologne, Cologne, Germany; School of Science Department of Physics, National and Kapodistrian University of Athens, Athens, Greece.
Artemis
A
Travlou
Institute of Movement and Sport Gerontology, German Sport University Cologne, Cologne, Germany.
Peter
P
Krauss
Faculty of Mathematics and Technology, University of Applied Sciences, Remagen, Germany.
Uwe
U
Jaekel
D000328:Adult; D000465:Algorithms; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D013710:Tendons / Q000000981:diagnostic imaging* / Q000502:physiology*; D014463:Ultrasonography / Q000379:methods*
Achilles tendon; Automatic tracking; Lucas–Kanade; Optical flow; Ultrasound; Voluntary contraction