1 / 56

Understanding Doppler and its Current Uses in OB

Understanding Doppler and its Current Uses in OB. Diana M. Strickland, BSBA, RDMS, RDCS. Continuous vs. Pulsed. Doppler – Moving structures - Red Blood Cells-. Wall motion – high level NOISE!. Scattered waves- low level NOISE!. ƒd = 2( ƒt • v • cos θ)/c.

babu
Download Presentation

Understanding Doppler and its Current Uses in OB

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Understanding Doppler and its Current Uses in OB Diana M. Strickland, BSBA, RDMS, RDCS

  2. Continuous vs. Pulsed

  3. Doppler – Moving structures-Red Blood Cells- Wall motion – high level NOISE! Scattered waves- low level NOISE! ƒd = 2(ƒt • v • cosθ)/c

  4. Doppler – Moving structures-Red Blood Cells- fr fr ft ft Positive shift f Negative shift Time

  5. Doppler – Moving structures-Red Blood Cells- ft ? f time

  6. ft f time

  7. Doppler – Moving structures-Red Blood Cells- Optimal ft <20o

  8. Doppler modes are differentiated by the way the signal is processed

  9. FFT – Fast Fourier Transform • Algorithm to display multiple frequencies in a single time frame – Spectral Doppler • Think of a single note versus a chord • Color Doppler is an average of the spectral doppler – it can’t show each frequency in a specific time unit • Standard display is BART – Blue away, Red towards • Density of blood cells displayed as an intensity of gray • High density (power) – bright • Low density (power) – less bright • Is power useful in Spectral Doppler – NO, but it is in Power Doppler • Color tone determined by density (#) of cells

  10. Diastole Plug Flow - Systole Consider spread through sample volume

  11. Broadening / Narrowing Frequency S D Envelope Time

  12. Adjusting Parameters • Gain • Scale • Baseline • Filter • Gate • Sweep

  13. Adjusting Parameters • Gain • Scale • Baseline • Filter • Gate • Sweep

  14. Adjusting Parameters • Gain • Scale • Baseline • Filter • Gate • Sweep

  15. Adjusting Parameters • Gain • Scale • Baseline • Filter • Gate • Sweep

  16. Adjusting Parameters • Gain • Scale • Baseline • Filter • Gate • Sweep

  17. Adjusting Parameters • Gain • Scale • Baseline • Filter • Gate • Sweep

  18. Adjusting Parameters • Gain • Scale • Baseline • Filter • Gate • Sweep

  19. Adjusting Parameters • Gain • Scale • Baseline • Filter • Gate • Sweep

  20. Adjusting Parameters • Gain • Scale • Baseline • Filter • Gate • Sweep

  21. Invert Size

  22. Other causes for poor Doppler signal… • Frequency of transducer too high for vessel depth • Lower frequency • Receiver gain too low • Increase gain • Focal zone not optimized to area of interest – the vessel • Move it ;-)

  23. Fetal Well Being • NST • BPP • Doppler

  24. Fetal Well Being Maximum Systole / Minimum Diastole S / D (S-D) RI (Resistance Index or Pourcelot Index) S (S-D) PI (Pulsatilty Index) A TAMV Time-averaged mean velocity

  25. Middle Cerebral ArteryMCA • Placental Insufficiency • Anemia (Isoimmunization / Parvo)

  26. MCA – Circle of Willus ACo BA IC ACA PCA PCoA MCA

  27. MCA – Placental Insufficiency • CerebroPlacental Ratio – CPR • Originally used the anterior cerebral artery • Wladimiroff, et al. • RI c / RI u • >1 Normal, <1 Redistribution • MCA RI • <70 Indicative of Redistribution • Others • Umb Artery RI • Umb Artery PI • MCA PI • MCA TAMV • Thoracic Aorta PI • Thoracic artery TAMV • UA/MCA PI ratio • MCA/Thoracic Aorta PI ratio • MCA PI x Thoracic TAMV

  28. MCA – Placental Insufficiency • Valuable when fetus is reacting to hypoxia • When physiological responses to hypoxia become exhausted, fetus cannot adapt further • Decline of forward cardiac function (increase venous doppler indices) • Deregulation of cardiovascular homeostasis may be seen and arterial circulation indices become less reliable.

  29. MCA – Placental Insufficiency Increased diastolic umbilical vein flow = GOOD Increased diastolic cerebral flow - may signal placental problem

  30. Anemia Viscosity = # of red blood cells

  31. Viscosity - Normal

  32. Viscosity - Anemia

  33. MCA – Anemia • Fetuses healthy and w/ anemia mild, moderate, and severe. • Linear models fitted to data for individual fetuses – slope was determined • Average rate of change as a function of GA • MCA-PSV – expressed as MoM • Healthy vs. Mild anemic – NS • Healthy vs. Severely anemic (P=.01) • Conclusion – excellent tool to predict which fetuses will become severely anemic Detti, Mari, Moise et al, AJOG Oct 2002

  34. MCA - Anemia • Peak Velocity (w/fetal blood sampling) • Sensitivity for moderate or severe anemia 100% FPR 12% fetuses w/o hydrops (Mari, et al, NEJM Jan 2000) • Fetuses w/Parvo B19 Sens /Spec 100/100% slightly less in alloimmune group (included post transfusion follow-up) (Delle Chiaie, et al, USOG Sep 2001) • Correlation between Hemoglobin and MCA-PSV becomes more accurate as severity of anemia increases. (Mari, et al, OG Apr 2002) • TAMV (Abdel-Fattah, et al, BJR Sep 2002)

  35. IVC/SVC doppler • Influenced by heart rate, RH hemodynamics and function, and AMOUNT of blood flowing through veins • Reciprocal shift observed between IVC and SVC velocity waveforms (Smin) • Changes another manifestation of blood flow redistribution toward the brain • May be good to use prior to 30 weeks when doppler findings more difficult to interpret

  36. Fetal Echo • Critical to evaluate flow an GV anomalies • Quantitate flow – Artery size, volume, VTI • Direction of flow • Presence of flow • Quality of flow – turbulence • Tei Index – (TI) MV & LV flow in one waveform • Tissue Doppler MV LV

More Related