Doppler uses in renal patients.

1. Doppler Ultrasound in renal
patients
The essentials
Dr/Ahmed Bahnassy
Consultant Radiologist
MBCHB-MSc-FRCR(UK)

2. Aim of the lecture
• highlighting the essential role of doppler in
renal ultrasound examination.
• illustrating the role of doppler in renal
transplant evaluation.
• expaining the role of doppler in renal
failure patients as pre-operative planning
to AV fistula for dialysis and monitoring its
function and complications.

4. Anterior approach

5. Oblique approach

6. Transverse B-mode view of the abdominal aorta
and right renal artery from an anterior approach.
The ultrasound probe is oriented at midline and
the Doppler cursor placed in the proximal right renal
artery.
The angle of incidence of the Doppler beam to the
flow is unacceptable at approximately 89 degrees.
By moving the probe to the left of
midline and angling toward the patient’s
right, an acceptable Doppler angle of
60 degrees is achieved

8. Flank approach

9. The Doppler sample volume is placed
within the proximal right renal artery. In
this view, an acceptable Doppler angle of
60 degrees or less is easily obtained.

10. values

11. Normal

12. Methods of evaluation of RA
• Direct visualization
• with Doppler
• throughout the Main
• renal artery and all
• accessory renal
• arteries
• • Indirect Evaluation
• – Doppler of the
• segmental/interlobar
• renal arteries at the
• upper, mid and lower
• renal poles
• The most reliable approach
combines the two methods.

13. Criteria for Renal Artery Stenosis
Direct Evaluation
• Velocities greater than 200 cm/sec have been shown to indicate a
>60% RAS.
• Post-stenotic turbulence must be documented beyond any focal
velocity increase to confirm stenosis.
• Bruits seen in Color Doppler or in the spectral waveform can also
increase diagnostic confidence and aid in localization of a stenosis.
• The RAR is calculated by dividing the highest peak systolic velocity
in the renal artery by the normal aortic velocity. An RAR greater than
3.5 is considered abnormal.
The use of the RAR instead of the absolute PSV value is preferable
since hypertension
itself can cause increased PSV velocities in all the vessels in
hypertensive patients

14. Image A is a color Doppler image of a stenotic right renal artery origin.
A color bruit is seen in the tissue surrounding the area of the post stenotic turbulence.
The presence of the bruit can help to identify the location of the stenosis and increase
diagnostic confidence.

15. A Doppler reading(B) obtained near the renal artery origin shows velocities over 600
cm/s in systole and over 300 cm/s in diastole consistent with a high grade stenosis.

16. Image C shows a spectral waveform obtained in the area of poststenotic
turbulence just beyond
the maximal area of stenosis.
The velocity is lower at 317 cm/s and the waveform profile is irregular due to the
turbulent flow.

17. Tardus–parvus waveform in a patient with RA stenosis. Note the delayed and
dampened
upstroke yielding a rounded appearance to the waveform.

18. The ESP is detected on each waveform.
• In some cases, the ESP is the highest peak, but in
others, the highest peak occurs later in systole.
• The AT is always measured to the first systolic peak,
which is the ESP in normal waveforms.
Since the ESP is absent on abnormal waveforms, the AT is
measured from the beginning of systole to the systolic
peak. These waveforms are termed tardus parvus due
to the delayed systolic acceleration

19. Fibromuscular dysplasia

20. FMD

21. Atheromatous plaque

22. Atheromatous stenosis

23. Alliasing effect

24. Severe stenosis criteria

25. Absent pic

26. Stenosis grading

27. Renal artery dissection

28. Renal artery dissection

29. AVM

30. AVM

31. AVF

32. AVF

33. Aneurysm

34. Nutcracker

38. Renal mass

39. Normal variants

42. Nephropathies

44. Lithiasis

45. twinkle artefact

46. Hydronephrosis

52. Renal vein evaluation

53. Renal vein thrombosis

55. Renal transplant evaluation

56. Rejection
The edema leads to increased
vascluar resistance and elevation
of the resistive index.
However, the finding of increased
resistive index is a non-specific
finding which can also be seen in
the setting of infection, acute
tubular necrosis, perioperative
ischemia, hydronephrosis and
extrinsic compression

57. ATN

58. Infarction

59. RAS

60. Renal vein anastomotic stenosis

61. RV thrombosis
• Venous thrombosis can occur secondary to infection,
severe rejection or technical problems with the
anastomosis.
• The diagnostic ultrasound findings include absence of flow
on Power color and spectral Doppler analysis.
• Venous thrombosis results in a high-resistance vascular
circuit and can result in subsequent reversal of diastolic
flow in the arterial waveform;
• however, reversed diastolic flow is a nonspecific finding
which can be seen in severe rejection, severe
pyelonephritis, drug toxicity and extrinsic compression.

62. RV thrombosis

63. AV fistula

65. AV shunt evaluation

68. Changes after fistula

69. • Preoperative color Doppler ultrasound criteria
• for good AVF outcome :
• Arterial luminal diameter
• - >1.6 mm (internal diameter)
• Venous luminal diameter
• - >2.0 mm / 3mm (without use of a tourniquet)
• Arterial resistance index
• - <0.7 ( at reactive hyperemia) fist test

70. Preoperative colour Doppler ultrasound of the radial artery, showing a change from
triphasic high-resistance to biphasic low-resistance Doppler waveform at reactive
hyperaemia.

71. mapping

72. Post operative assesment
Good mature draining vein
Diameter > 6mm
Depth < 6mm
No branches

73. • Assessment of blood volume
• flow of the shunt:
• Access volume flow / adequacy /
• function :
•  Normal ………… around….. 500 ml / m
•  Malfunction … …..below…... 250 ml / m
•  Above …………………………… 1000 ml /m
• forearm-arm
•  Risk of cardiac failure / hand ischemia ?

74. • Places of volume assessment
•  Inflow / feeding
•  Outflow / draining
•  Access assessment
AVF :
• GRAFT : along the graft

75. Feeding artery

76. Shunt
High flow velocity in shunt more than 250 cm/sec
& characteristic low resistive flow

77. High flow fistula [ near 1000 ml /
min ] showing
proximal and distal flow in opposite
direction .

78. Complications:1.stenosis

80. Graft stenosis

81. Venous stenosis-intimal
hyperplasia

82. Arterial stenosis
Significant stenosis at the anastomosis,
with an elevated peak systolic velocity
of 696 cm/s
Venous stenosis, with an elevated peak
systolic velocity of 662 cm/s

83. Significant anastomotic stenosis

84. 2.Thrombosis

86. changing arterial waveform dt
fistula thrombosis

87. 3.Haematoma

88. Post operative haematoma

89. 4.Aneurysm

90. True venous aneurysm

91. 5.Steal syndrome
• Clinical condition caused by arterial
• insufficiency distal to a hemodialysis access
• • Usually associated with reversal of distal flow
• • Incidence around 3-5%
• • Can progress to irreversible neuropathy , loss
• of function (claw hand), gangrene, digit loss,
• limb loss

92. Hand pain
• Diminished/altered sensation
• Pale, cold hand
• Diminished/absent pulses
• Weakness
• Ischemic monomelic neuropathy

93. Haemodynamics

94. Reversed flow

95. Diagnosis
Proximal Distal

96. 6.pseudoaneurysm
risk of
rupture

97. 7.poor outflow
good outflow poor outflow