title: Evaluation of ultrasound Tissue Velocity Imaging: a phantom study of velocity estimation in skeletal muscle low-level contractions.
abstract: BACKGROUND
  Tissue Velocity Imaging (TVI) is an ultrasound based technique used for quantitative analysis of the cardiac function and has earlier been evaluated according to myocardial velocities. Recent years several studies have reported applying TVI in the analysis of skeletal muscles. Skeletal tissue velocities can be very low. In particular, when performing isometric contractions or contractions of low force level the velocities may be much lower compared to the myocardial tissue velocities.
  
  
  METHODS
  In this study TVI was evaluated for estimation of tissue velocities below the typical myocardial velocities. An in-house phantom was used to see how different PRF-settings affected the accuracy of the velocity estimations.
  
  
  RESULTS
  With phantom peak velocity at 0.03 cm/s the error ranged from 31% up to 313% with the different PRF-settings in this study. For the peak velocities at 0.17 cm/s and 0.26 cm/s there was no difference in error with tested PFR settings, it is kept approximately around 20%.
  
  
  CONCLUSIONS
  The results from the present study showed that the PRF setting did not seem to affect the accuracy of the velocity estimation at tissue velocities above 0.17 cm/s. However at lower velocities (0.03 cm/s) the setting was crucial for the accuracy. The PRF should therefore preferable be reduced when the method is applied in low-level muscle contraction.
authors.affiliation: School of Technology and Health, Royal Institute of Technology (KTH), Huddinge, Sweden. frida.lindberg@sth.kth.se
authors.forename: Frida
authors.initials: F
authors.lastname: Lindberg
authors.forename: Mattias
authors.initials: M
authors.lastname: Mårtensson
authors.forename: Christer
authors.initials: C
authors.lastname: Grönlund
authors.forename: Lars-Åke
authors.initials: LÅ
authors.lastname: Brodin
mesh_terms: D000465:Algorithms; D032701:Biomimetics / Q000379:methods; D054459:Elasticity Imaging Techniques / Q000295:instrumentation* / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging* / Q000502:physiology*; D019047:Phantoms, Imaging; D005082:Physical Exertion / Q000502:physiology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity