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.
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
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.
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
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
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.
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.
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
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
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