This document discusses Doppler ultrasound imaging controls and parameters. It covers adjusting the box/gate angle, size, and location to optimize flow visualization. Other important controls include pulse repetition frequency to avoid aliasing, baseline, gate size, gains, velocity scale, Doppler frequency, and wall filter. Keeping the imaging angle below 60 degrees minimizes velocity estimation errors. Proper settings of these Doppler parameters are necessary to accurately analyze blood flow velocities.

1. Doppler 102
Controls
Image optimization

2. Controls
o The flow : box/gate angle
o Box size and location
o The PRF
o Baseline
o The gate size
o Update
o Gain (Colour and Spectral)
o The velocity scale
o Doppler Frequency
o The wall filter
o Pseudocolour

3. Controls
o The flow : box/gate angle
o Box size and location
o The PRF
o Baseline
o The gate size
o Update
o Gain (Colour and Spectral)
o The velocity scale
o Doppler Frequency
o The wall filter
o Pseudocolour

4. The Angle

5. Cos 0 = 1
Cos 90 = 0
Angle Actual
velocity
Estimated
velocity
Percent
error
0 50cm/sec 50.2cm/sec 0.4%
20 50cm/sec 51.8cm/sec 3.6%
40 50cm/sec 54.2cm/sec 8.4%
60 50cm/sec 59.2cm/sec 18.3%
80 50cm/sec 99.6cm/sec 99%

6. Keep your angle below 60o!

7. Angle Dependence

8. Angle Dependence
© Shlomo Gobi, Jerusalem

9. Angle Dependence
© Shlomo Gobi, Jerusalem

10. Angle dependence

11. Get the box/gate:vessel
relationship right in angled
vessels

12. Get the box/gate:vessel
relationship right in angled
vessels

13. Get the box/gate:flow
relationship right in parallel
vessels

14. Swinging/Steering the box

15. Swinging/Steering the box

17. Angles for Spectral Analysis are
Equally Important

18. Controls
o The flow : box/gate angle
o Box size and location
o The PRF
o Baseline
o The gate size
o Update
o Gain (Colour and Spectral)
o The velocity scale
o Doppler Frequency
o The wall filter
o Pseudocolour

19. Box size and location
o Bigger box
o Deeper box
Slows frame rate

20. Box Location

21. Box Size

22. Controls
o The flow : box/gate angle
o Box size and location
o The PRF
o Baseline
o The gate size
o Update
o Gain (Colour and Spectral)
o The velocity scale
o Doppler Frequency
o The wall filter
o Pseudocolour

23. PRF
(Pulse Repetition Frequency)
o Sampling rate for Doppler
o Use high PRF for high flows, and vice versa
o Increase PRF for tackling aliasing

24. Aliasing
Sampling every 45 minutes

25. Aliasing

26. Aliasing

27. PRF

28. The PRF

29. Controls
o The flow : box/gate angle
o Box size and location
o The PRF
o Baseline
o The gate size
o Update
o Gain (Colour and Spectral)
o The velocity scale
o Doppler Frequency
o The wall filter
o Pseudocolour

30. Baseline

31. Controls
o The flow : box/gate angle
o Box size and location
o The PRF
o Baseline
o The gate size
o Update
o Gain (Colour and Spectral)
o The velocity scale
o Doppler Frequency
o The wall filter
o Pseudocolour

32. The Doppler Gate

33. Gate size

34. Gate size

35. Gate size

36. Gate size
Wide gate steps on both artery and vein

37. Controls
o The flow : box/gate angle
o Box size and location
o The PRF
o Baseline
o The gate size
o Update
o Gain (Colour and Spectral)
o The velocity scale
o Doppler Frequency
o The wall filter
o Pseudocolour

38. Update

39. Colour Gain
Gain max Gain zero

40. Spectral Gain

41. Spectral Gain
Reducing Spectral Gain reduces Mirror Artifacts

42. Controls
o The flow : box/gate angle
o Box size and location
o The PRF
o Baseline
o The gate size
o Update
o Gain (Colour and Spectral)
o The velocity scale
o Doppler Frequency
o The wall filter
o Pseudocolour

43. Velocity range
Velocity range 5 Velocity range 16

44. Velocity range
Velocity 3 Velocity 16

45. Controls
o The flow : box/gate angle
o Box size and location
o The PRF
o Baseline
o The gate size
o Update
o Gain (Colour and Spectral)
o The velocity scale
o Doppler Frequency
o The wall filter
o Pseudocolour

46. Doppler frequency
Frequency 4.2 MHz Frequency 5.2 MHz

47. Doppler frequency

48. Controls
o The flow : box/gate angle
o Box size and location
o The PRF
o Baseline
o The gate size
o Update
o Gain (Colour and Spectral)
o The velocity scale
o Doppler Frequency
o The wall filter
o Pseudocolour

49. Wall filter

50. Controls
o The flow : box/gate angle
o Box size and location
o The PRF
o Baseline
o The gate size
o Gain (Colour and Spectral)
o The velocity scale
o Doppler Frequency
o The wall filter
o Pseudocolour

51. Pseudocolour

52. Artifacts

53. Artifacts
o Mirror
o Aliasing
o Temporal artifact
o Movement artifact

54. Mirroring

55. Mirroring

56. Mirroring

57. Aliasing

58. Aliasing

59. Movement artifact

60. Power Doppler

61. Power Doppler
o Usually no directional information
o Less angle dependent
o Slow frame rate

63. Colour Doppler
M Mode

64. Colour Doppler M Mode

65. Colour : B ratios

66. B Flow

67. Thank you

68. Temporal resolution