Renal Doppler Indications and Detection of Pathologies

1. Doppler US of the kidneys
• Normal anatomy of the kidney
• Normal US of the kidney
• Normal Doppler US of the kidney
• Indications of renal Doppler ultrasound

2. Pheochromocytoma
Uncommon – 1 % of patients with hypertension
Highly vascularized
right pheochromocytoma
1 Jenssen C et al. Ultraschall Med 2010 ; 31: 228 – 250.
2 Wan YL et al. J Med Ultrasound 2007 ; 15 : 213 – 227.
10% Extra-adrenal [paraganglioma]
10% of them extra-abdominal
10% Malignant
10 % Multiple masses
“rules of 10” 2

3. Micronodular cortical hyperplasia of right adrenal gland
Structure measuring approximately 5 mm
& isoechoic to adrenal cortex
Conn’s sydrome / adrenal hyperplasia
Jenssen C et al. Ultraschall Med 2010 ; 31: 228 – 250.

4. Indications of renal Doppler ultrasound
 Renal artery stenosis
 Renal artery thrombosis & emboli
 Renal vein thrombosis
 Aneurysm & pseudo-aneurysm
 Arterio-venous communications
 Nutcracker syndrome
 Renal mass
 Miscellaneous indications

5. Renal artery stenosis
1 – 5% of hypertensive population
• Atherosclerosis
• Fibromuscular dysplasia (FMD)
• Dissection
• Embolization
• Aortic coarctation
• Renal Artery Aneurysm
• Arteritis
• Congenital
• Neurofibromatosis
• Irradiation
> 95 % of cases

6. Renal artery stenosis
Atherosclerosis
> 90%
FMD
< 10%
Age After age of 50 Young
Gender More common in males More common in females
Location Proximal 1 cm of main RA
Branching points
Middle of renal artery
Others (carotids)
Post-stenotic
dilatation
Rare Frequent

7. Clinical risk factors for renovascular HTN
• Abrupt onset of severe HTN: diastolic >120 mm Hg
• Accelerated or malignant HTN: grade III or IV retinopathy
• HTN refractory to appropriate three-drug regimen
• Onset of hypertension before age 30 or after age 60
• HTN with rapidly progressive renal failure
• Renal failure that develops in response to ACE inhibitor
• HTN associated with upper abdominal bruit
• Episodes of recurrent severe HTN & pulmonary edema
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.

8. Renal artery stenosis
Direct signs
Focal color aliasing
Color bruit
Turbulence
PSV > 180 cm/sec
Renal Aortic Ratio > 3.5
Indirect signs
AT > 0.07 sec
AI < 3 m/s2
Δ RI (right – left) > 5 %
Significant stenosis
(50 – 85% diameter reduction)
Sensitivity: 79 – 91%
Specificity: 73 – 97%
Severe stenosis
(> 85 % diameter reduction)
Sensitivity: 95%
Specificity: 97%

9. Renal artery stenosis / Direct criteria
Non-significant stenosis (< 50% diameter stenosis)
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
Plaque in anterior wall of LRA
PSV: 148 cm/sec
Color Doppler US Power Doppler US
Better visualization of plaque

10. Renal artery stenosis / Direct criteria
PSV: 275 cm/sec
High-grade stenosis
Aliasing in left renal artery
Schäberle W. Ultrasonography in vascular diagnosis.
Springer-Verlag, Berlin Heidelberg, 2nd edition, 2011.

11. Renal artery stenosis / First Generation CEUS
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
Baseline color Doppler
RRA not identified
Aliasing of SMA origin
Pulse Doppler image
PSV > 300 cm/s
Severe stenosis of RRA
IV contrast agent
RRA visualized
Focal color aliasing

12. PSV: 293 cm/sec – RI : 0.91
Controversial indication of PTA2
Aliasing in left renal artery
Retro-aortic course of LRV
1 Schäberle W. Ultrasonography in vascular diagnosis. Springer-Verlag, Berlin, 2nd edition, 2011.
2 Jaeger KA et al. Ultraschall in Med 2007 ; 28 : 28 – 31.
Renal artery stenosis / Direct criteria

13. Creatinine clearance after correction of RAS
according to RI before revascularization
Radermacher J et al. N Engl J Med 2001 ; 344 : 410 – 417.
131 pts with unilateral or bilateral RAS > 50 % of luminal diameter
Renal angioplasty or surgery

14. Renal artery stenosis / Renal Aortic Ratio
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
Small right kidney (8.4 cm) PSV (aorta): 102 cm/s
PSV (RRA): 465 cm/s High grade stenosis of RRA
RAR: 4.5

15. Renal artery stenosis / Indirect criteria
Schäberle W. Ultrasonography in vascular diagnosis.
Springer-Verlag, Berlin, 2nd edition, 2011.
PSV: 85.7 cm/s
EDV: 47.2 cm/s
RI: 0.64
Left renal hilumRight renal hilum
PSV: 125 cm/sec
EDV: 58.1 cm/s
RI: 0.75
Δ RI (right – left) > 0.05 → RA stenosis in side of lower RI

16. Renal artery stenosis / Tardus-Parvus wave
Severe stenosis (> 85 % diameter reduction)
Tardus: Longer rise time
Parvus: Low PSV
Freeman SJ. Ultrasound 2004 ; 12 : 69 – 74.

17. Tardus-Parvus wave
• Mimics Abdominal coarctation
William syndrome
Aortic/mitral valve disease
Left ventricle dysfunction
CV medications: after-load reducers
• Exaggerating 25 mg captopril 1 hour before exam
• Minimizing Age – HTN – DM (vessel compliance)
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.

18. Abdominal aortic aneurysm & renal arteries
Zubarev VZ. Eur Radiol 2001 ; 11 : 1902 – 1915.
Aneurysm arises below origin of both renal arteries

19. Fibromuscular dysplasia
Moniliform aspect of RRA
Typical FMD in middle third of RRA
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
PSV 250 cm/sec
No parallelism of RRA walls

20. Etiologies of renal artery dissection
Stenotic or occlusive lesion
• Atherosclerosis
• Fibromuscular dysplasia
• Extension of aortic dissection
• Marfan syndrome & Ehlers-Danlos syndrome
• Trauma & iatrogenic causes
• Idiopathic
Sidhu R et al. Semin Ultrasound CT MRI 2009 ; 30 : 271 – 288.

21. Renal artery dissection
Flank pain & hematuria – Stenotic or occlusive lesion
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
Interruption of LRA « bec de flûte »
Associated thrombosis of LRV
Occlusion of LRA at its origin
Complete necrosis of LK

22. Coarctation of abdominal aorta
Severe hypertension in a 6-year-old boy
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
Bilateral & symmetric
tardus parvus waveform
Sagital view of aorta
Severe narrowing at level of CA & SMA

23. Guidelines for diagnosis of RAS
• Recommended as screening test
Duplex US followed by
CT angiography (except RF) & MR angiography
• Not recommended as screening test
Captopril renal scintigraphy
Plasma renin activity
Captopril test
Selective renal vein renin measurements
Hirsch AT et al. J Am Coll Cardiol 2006 ; 47 : 1239 – 1312.

24. Indications of renal Doppler ultrasound
 Renal artery stenosis
 Renal artery thrombosis & emboli
 Renal vein thrombosis
 Aneurysm & pseudo-aneurysm
 Arterio-venous communications
 Nutcracker syndrome
 Renal mass
 Miscellaneous indications

25. Renal artery thrombosis
• Causes Embolism: most common
Thrombosis – trauma – hypercoagulable
state
• SymptomsAcute flank pain + hematuria
• Impression Renal stone
Leaking abdominal aortic aneurysm
• Doppler US Normal side: normal arterial & venous flow
Affected side: no arterial flow – venous flow

26. Renal artery thrombosis / Complete
Irshad A et al. Semin Ultrasound CT MRI 2009 ; 30 : 298 – 314.
Absence of flow within kidney
Power Doppler US Power Doppler US more medially
Flow in iliac artery
& proximal anastomotic artery

27. Renal artery thrombosis / Partial
Caia S et al. Clinical Imaging 2008 ; 32 : 367 – 371.
Slender flow in main renal artery
Color Doppler US Pulsed Doppler US
Low velocity: PSV 40 cm/s
Low resistance: RI 0.5

28. Renal artery embolism
Caia S et al. Clinical Imaging 2008 ; 32 : 367 – 371.
Low PSV in main renal artery
No blood flow in upper pole Normal blood flow in lower pole

29. Indications of renal Doppler ultrasound
 Renal artery stenosis
 Renal artery thrombosis & emboli
 Renal vein thrombosis
 Aneurysm & pseudo-aneurysm
 Arterio-venous communications
 Nutcracker syndrome
 Renal mass
 Miscellaneous indications

30. Doppler US in acute renal vein thrombosis
Acute flank pain & hematuria
• High RI in intra-renal arteries
Reversed flow in diastole
• Absence of flow in intra-renal veins
• Enlarged main renal vein with no flow

31. Acute renal vein thrombosis
Absence of color signal
in main right renal vein
Reversed diastolic flow in
main renal artery
Kraft JK.& Brandão LR. Pediatr Radiol 2011 ; 41 : 299 – 307.
LRV more commonly involved (longer length)

32. Acute renal vein thrombosis / Poor outcome
• Reduced perfusion at diagnosis
• Subcapsular fluid collections
• Profoundly hypoechoic & irregular renal pyramids
• Patchy cortical echotexture
Likely reflecting cortical infarction & hemorrhage
Kraft JK.& Brandão LR. Pediatr Radiol 2011 ; 41 : 299 – 307.

33. Acute renal vein thrombosis / Poor outcome
Kraft JK.& Brandão LR. Pediatr Radiol 2011 ; 41 : 299 – 307.
Severely decreased renal perfusion
Right kidney
Normal perfusion for comparison
Left kidney

34. Subcapsular fluid
collections
Hypoechoic & irregular pyramids
Patchy hypoechoic areas in cortex
Kraft JK.& Brandão LR. Pediatr Radiol 2011 ; 41 : 299 – 307.
Acute renal vein thrombosis / Poor outcome

35. Chronic renal vein thrombosis / Collateral flow
No flow in main right renal vein
Collateral flow clearly seen
Zubarev VZ. Eur Radiol 2001 ; 11 : 1902 – 1915.
Kraft JK.& Brandão LR. Pediatr Radiol 2011 ; 41 : 299 – 307.
Capsular collateral veins
Linear calcifications in parenchyma

36. Indications of renal Doppler ultrasound
 Renal artery stenosis
 Renal artery thrombosis & emboli
 Renal vein thrombosis
 Aneurysm & pseudo-aneurysm
 Arterio-venous communications
 Nutcracker syndrome
 Renal mass
 Miscellaneous indications

37. Renal artery aneurysms
Extraparenchymal in 90% of cases
• Causes Atherosclerosis – FMD
Collagen deficiencies – Phacomatosis
• Gender More common in females
• Age Young patients
• Location Main renal artery or at bifurcation
• Wall Thin (risk of rupture)
• Treatment > 2.5 cm in diameter
Surgery (nephrectomy – kidney-sparing)

38. Aneurysm of left renal artery
Gao J et al. Clinical Imaging 2006 ; 30 ; 140 – 142.
Gray-scale US Color Doppler US
Angiography

39. Micro-aneurysms
Contraindication of renal biopsy (bleeding)
• Location Distal branches of cortex
Segmental arteries rarely
• Size 1 mm, 2-3 mm rarely
• Cause PAN (micoaneurysms in 100%)
• Clinic Fever – Abdominal pain – Hematuria – RF
• Diagnosis Arteriography – Not visible by Doppler
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.

40. Renal pseudo-aneurysm
• Causes Iatrogenic (percutaneous procedure) –
Trauma
• Incidence Unknown
• Clinic Silent Small & resolve uneventfully
Hematuria Communicate with collecting cyst
Bleeding Rupture in perirenal space
• Rx Small Monitoring until they resolve
Large Transcatheter embolization

41. Pseudo-aneurysm
Sampling at neck To-and-fro waveform
“To” Systole
“Fro” Diastole

42. “to and fro waveform”
within neck of the lesion
Cystic lesion in middle of RK
Bi-directional flow
“yin -yang pattern”
Rashid M et al. Emerg Radiol 2007 ; 14 : 257 – 260.
Renal pseudo-aneurysm