This document provides information on performing and interpreting renal Doppler ultrasounds. It discusses the optimal approaches for imaging the renal arteries, including the anterior, oblique, and flank approaches. It also outlines criteria for evaluating renal artery stenosis, including peak systolic velocity measurements and the renal-aortic ratio. Common renal pathologies that can be identified with Doppler ultrasound are also summarized, such as fibromuscular dysplasia, atherosclerosis, aneurysms, and hydronephrosis.

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

3. Anterior approach

4. Oblique approach

5. 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

7. Flank approach

8. 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.

9. values

10. Normal

11. 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.

12. 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

13. 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.

14. 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.

15. 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.

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

17. 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

18. Fibromuscular dysplasia

19. FMD

20. Atheromatous plaque

21. Atheromatous stenosis

22. Alliasing effect

23. Severe stenosis criteria

24. Absent pic

25. Stenosis grading

26. Renal artery dissection

27. Renal artery dissection

28. AVM

29. AVM

30. AVF

31. AVF

32. Aneurysm

33. Nutcracker

37. Renal mass

38. Normal variants

41. Nephropathies

43. Lithiasis

44. twinkle artefact

45. Hydronephrosis

51. Renal vein evaluation

52. Renal vein thrombosis