Doppler 102
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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.
Doppler 102
- 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!
- 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
- 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
- 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
- 60. Power Doppler
- 61. Power Doppler o Usually no directional information o Less angle dependent o Slow frame rate
- 64. Colour Doppler M Mode
- 65. Colour : B ratios
- 66. B Flow
- 67. Thank you