Test 4 Chapters 14-18

  1. What denotes maximum velocity in both directions that can be displayed without aliasing?
    Velocity Scale
  2. What removes data below a specific frequency?
    Wall filter
  3. What assigns various shades of color and brightness to depict different velocities?
    Color map
  4. What is it when the color doppler information wrapping around color bar when velocities exceed Nyquist limit?
  5. What is improper assignment of color due to movement of tissue?
  6. What control should be adjusted to show more detail in the waveform?
    Sweep speed
  7. What is zero area on Doppler display called?
  8. What sets the threshold below which weak flow signals are not displayed?
  9. What is it when the magnitude of each frequency component is plotted with respect to frequency?
    Power spectrum
  10. What shows magnitude of flow, not velocity information?
    Power Doppler
  11. What is the number of pulses used to interrogate single color line of sight?
    Ensemble length
  12. What is the 3-D region from where doppler information is obtained?
    Sample volume
  13. What is complete loss of flow coherence?
  14. What is vertical thickening of Doppler spectrum that corresponds to turbulent flow?
    Spectral broadening
  15. What is the display type where the x-axis is the time and y-axis is amplitude of doppler signal?
    Spectral waveform
  16. What is the mathematical formula that separates waveform into a series of single-frequency, sine waves?
    Fast Fourier Transform (FFT)
  17. What is it when flow in vessels changes over time, and blood flow patterns are displayed as a function of time?
    Doppler spectral waveform
  18. What are the three variables of Doppler spectral waveform?
    frequency, magnitude, and time are displayed
  19. What is the vertical axis of spectral display?
  20. What is the horizontal axis of spectral display?
  21. What is frequency information  of spectral display converted to?
    Velocity information
  22. What is detection mode where fewer transmit pulses are applied along the scan line as compared to spectral analysis, and as a result, are less sensative to slow flow and flow in smaller vessels?
  23. What are the number of pulses used to interrogate one color doppler scan line?
    Ensemble length
  24. Larger ensemble length equals what?
    more accurate frequency estimates that equal a lower frame rate
  25. What can reverse the color flow of an image?
    Color-map invert
  26. What causes amplification to all color Doppler signals?
    Color gain
  27. What sets threshold below which weak flow is not displaye, noise rejection technique, independent of 2D?
    Color reject
  28. What combines color flow data in successive frames for smoother appearance of flow, more averaging equals degraded temporal resolution?
    Color persistence
  29. What is eliminated if it don't meet minimum frequency citreia?
    • Color wall filter
    • (Can eliminate noise from wall motion if set too high, real velocity info may also be eliminated)
  30. What shows amplitude or intensity of doppler signal with no velocity info?
    Power Doppler
  31. What depends on sample volume and attenuation of surrounding tissue?
    Power Doppler
  32. What is not angle dependent and yields no directional information; uses increased persistence and very sensitive to motion artifact (flash)?
    Power Doppler
  33. What type of doppler has theses four factors; motion discrimination, temporal resolution, spatial resoution and uniformity?
    Color Doppler
  34. What causes no color flow to be displayed posterior to attenuation sturctures?
  35. What cause depth ambiguity artifact to occur and can place flow in a more superficial location?
    High Pusle Repition Frequency (PRF)
  36. What occurs if velocity is higher than range set by operator, inapropriate color display which "wraps around" from top of color bar to bottom, or vice versa?
    Color aliasing
  37. Attenuation, High PRF, Color aliasing, multiple angle artifact, mirror image artifact, color bleed, color noise, misregistration of color, and color bruit are all what?
    Color Doppler Artifacts
  38. Color flow Doppler alows the operator to evaluate a more broad area to help figure out where to use ___________  _________.
    Spectral Doppler
  39. What depends on the relative velocity between source and reciever, the transmitted frequency, the acoustic velocity of the medium, and the Doppler angle as given by the Doppler shift equation?
    Doppler shift frequency
  40. For a constant reflector velocity, the detected Doppler shift frequency decreases as the Doppler angle is __________.
  41. What predicts that an increase in reflector velocity will cause a higher Doppler shift frequency?
    Doppler shift equation
  42. A graphic plot of power spectrum as a function of time is called?
    Doppler spectral waveform
Card Set
Test 4 Chapters 14-18
Chapter 14-18