title: Speckle tracking ultrasound is independent of insonation angle and gain: an in vitro investigation of agreement with sonomicrometry.
abstract: OBJECTIVE
  It has been shown that speckle tracking ultrasound (STU) is capable of measuring peak strain accurately in vitro over a range of compression rates and amplitudes. The aim of this study was to investigate the influence of different angles of insonation with a range of scanner settings.
  
  
  METHODS
  A tissue-mimicking phantom was cyclically deformed to imitate the beating heart. With different combinations of scanner settings, strain was measured by STU using sonomicrometry as reference.
  
  
  RESULTS
  Over a majority of parameter combinations, speckle tracking measured strain accurately. However, a combination of large echocardiographic image displacements, low frame rates, and small sector depths resulted in increased difference between STU and sonomicrometry. The angle of insonation and gain setting did not affect STU.
  
  
  CONCLUSIONS
  Despite the limitations exhibited by image displacement, frame rate, and sector depth, STU remains a promising technique for angle-independent assessment of strain.
authors.affiliation: Department of Anaesthesia and Intensive Care, Aarhus University Hospital, Skejby, Aarhus, Denmark. ksi@studmed.au.dk
authors.forename: Kim
authors.initials: K
authors.lastname: Sivesgaard
authors.forename: Sara Dahl
authors.initials: SD
authors.lastname: Christensen
authors.forename: Hans
authors.initials: H
authors.lastname: Nygaard
authors.forename: J Michael
authors.initials: JM
authors.lastname: Hasenkam
authors.forename: Erik
authors.initials: E
authors.lastname: Sloth
mesh_terms: D000465:Algorithms; D016477:Artifacts; D004452:Echocardiography / Q000295:instrumentation / Q000379:methods*; D054459:Elasticity Imaging Techniques / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity