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

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

10. 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

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

12. Broadening / Narrowing
Frequency S D
Envelope
Time

16. Adjusting Parameters
Gain
Scale
Baseline
Filter
Gate
Sweep

17. Adjusting Parameters
Gain
Scale
Baseline
Filter
Gate
Sweep

20. Adjusting Parameters
Gain
Scale
Baseline
Filter
Gate
Sweep

21. Adjusting Parameters
Gain
Scale
Baseline
Filter
Gate
Sweep

22. Adjusting Parameters
Gain
Scale
Baseline
Filter
Gate
Sweep

23. Adjusting Parameters
Gain
Scale
Baseline
Filter
Gate
Sweep

24. Adjusting Parameters
Gain
Scale
Baseline
Filter
Gate
Sweep

25. Adjusting Parameters
Gain
Scale
Baseline
Filter
Gate
Sweep

26. Adjusting Parameters
Gain
Scale
Baseline
Filter
Gate
Sweep

27. Invert
Size

28. 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 ;-)

29. Fetal Well Being
NST
BPP
Doppler

30. 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

35. Middle Cerebral Artery MCA
Placental Insufficiency
Anemia (Isoimmunization / Parvo)

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

38. 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

39. 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.

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

41. Viscosity = # of red blood cells
Anemia
Viscosity = # of red blood cells

42. Viscosity - Normal

43. Viscosity - Anemia

45. 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

46. 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)

47. 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

49. 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

52. Uterine Artery Doppler
Continuous Wave Doppler / Intraplacental
IUGR (Chronic Hypertension) and Preeclampsia
High AFP
Little change seen in doppler indices after 26 weeks
More difficult to assess when they are abnormal

55. Ovarian Artery Doppler
Tumor Angiogenesis – limited vascular tone due to absence of the muscular tunica media
CD screening optimal in PM women
No cyclic change in ovarian volume
RI < .40
96.4% Sens., 98.8% Spec., 98.2 PPV in 14,317 patients
Kurjak, Fleischer, and Bourne

56. Ovarian Artery Doppler
Impedance values in benign vs. malignant lesions overlap
Studies now looking at arrangement and density of vessels
Neural Networks and Baysian networks are being developed and tested