title: Analysis of temporal requirements for myocardial tissue velocity imaging.
abstract: OBJECTIVE
  Movements of myocardial walls include components of high velocity and short duration calling for a high sampling rate in the acquisition of tissue velocity imaging data. This study aims at establishing the optimal sampling requirements for tissue velocity imaging measurements.
  
  
  RESULTS
  In 16 healthy individuals, tissue velocity imaging data were acquired at a frame rate of 141-203 frames/s for a subsequent off-line analysis using software enabling a reduction of the sampling rate to 50%, 25% and 12.5% of the initial frame rate. Different components of the myocardial velocity profile were measured at each of these frame rates. The deviation of the results from the initial values increased markedly at decreasing frame rates, producing an underestimation of peak systolic and diastolic velocities, most other measured parameters being overestimated. A cut-off point for an acceptable < or =10% deviation of the results corresponded to at least 70 frames/s for peak systolic and early diastolic velocity, and to at least 100 frames/s for other systolic and diastolic parameters.
  
  
  CONCLUSIONS
  A high sampling rate is essential for a proper rendering of tissue velocity imaging signals, too low frame rates resulting in inferior accuracy of the results. This should be kept in mind while viewing reported tissue velocity imaging data.
authors.affiliation: Department of Clinical Physiology, Karolinska Institute, Huddinge University Hospital, Stockholm, Sweden. britta.lind@clinphys.hs.sll.se
authors.forename: B
authors.initials: B
authors.lastname: Lind
authors.forename: J
authors.initials: J
authors.lastname: Nowak
authors.forename: J
authors.initials: J
authors.lastname: Dorph
authors.forename: J
authors.initials: J
authors.lastname: van der Linden
authors.forename: L A
authors.initials: LA
authors.lastname: Brodin
mesh_terms: D000293:Adolescent; D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology*; D003971:Diastole / Q000502:physiology; D015150:Echocardiography, Doppler; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000502:physiology; D012016:Reference Values; D012494:Sampling Studies; D013318:Stroke Volume / Q000502:physiology; D013599:Systole / Q000502:physiology