renal artery stenosis, renal artery thrombosis, renal vein thrombosis, nutcracker syndrome.

1. Doppler ultrasound of the kidneys
Samir Haffar M.D.
Assistant Professor of Internal Medicine

2. 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 US

3. Normal anatomy of the kidney
Paspulati RM et al. Ultrasound Clin 2006 ; 1 : 25 – 41.
Renal parenchyma: cortex & medullary pyramids
Renal sinus: arteries, veins, lymphatics, collecting system, & fat
Renal hilum: Concave, in continuity with renal sinus

4. Anatomy of renal arteries
RRA: Usually passes posterior to inferior vena cava
LRA: Usually courses posterior to left renal vein
Multiple renal arteries in 25% (inferior polar artery from aorta)

5. Arterial blood supply to the Kidney
Myers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.
Segmental artery
Apical, upper, middle, lower, posterior
Interlobular artery
Between renal pyramids
Glomerular arteriole
Main renal artery
Arcuate artery
Between cortex & medulla

6. Left renal vein
• Longer than right renal vein
• Averages 85 mm in length (range: 60 – 110 mm)
• Joined by adrenal, gonadal, lumbar, & hemiazygous
veins before crossing the aorta
• Different types: Pre-aortic 80 – 95%
Retro-aortic 2 – 3%
Circum-aortic 7 – 9%
Sidhu R et al. Semin Ultrasound CT MRI 2009 ; 30 : 271 – 288.

7. Variants of left renal vein
Retro-aortic LRV
Incidence: 2 – 3%
Circum-aortic LRV
Incidence: 7 – 9%
Sidhu R et al. Semin Ultrasound CT MRI 2009 ; 30 : 271 – 288.

8. Left-sided IVC
Myers KA & Clough A. Making sense of vascular ultrasound. Arnold, London, 2004.
Normal anatomy of IVC Anomalous left-sided IVC
Persistence of embryological AV

9. 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 US

10. Gray scale imaging first
• Kidneys Maximum renal length
Echogenicity of renal cortex
Thickness of renal cortex
Masses – hydronephrosis – renal calculi
• Aorta Plaque – thrombus – dissection – aneurysm
• Adrenal glands

11. Normal kidney
Longitudinal section Cross section
Rumack CM et al. Diagnostic Ultrasound. Elsevier-Mosby, St. Louis, USA, 3rd edition, 2005.
Renal capsule: echogenic line
Renal parenchyma: outer cortex & inner medulla pyramid
Central sinus complex: high echogenicity (vessels, fat, fibrous tissue)

12. Renal dimensions
• Length of normal kidney: 9 – 14 cm
Right kidney smaller than left kidney
• Discrepancy > 2 cm between two kidneys:
Considered significant & needs further evaluation
• Renal length between 8 – 9 cm
Correlated to patient’s phenotype particularly height
• Renal length < 8 cm definitely reduced
Should be attributed to chronic renal failure
Fiorini F et al. J Ultrasound 2007 ; 10 : 161 – 167.

13. Measurement of parenchymal & cortical thickness
Cortical thickness: Normal 8 – 10 mm
Parenchymal thickness: Normal 14 – 18 mm
Tuma J et al. European course book: Genitourinary ultrasound.
European Foundation of Societies of Ultrasound in Medicine & Biology.

14. Renal volume
Length: 9 – 14 cm (longitudinal section)
Width: 4 – 6 cm (cross section)
Depth: 4 – 6 cm (cross section)
Ellipsoid formula: length . width . thickness . π/6
Derchi LE et al. Acad Radiol 1994 ; 1 : 100 – 105.
Fiorini F et al. J Ultrasound 2007 ; 10 : 161 – 167.
Adjusted to BMI
(V / BMI) . 25
Appropriate renal volume
231 ± 50 ml

15. Classification of renal parenchymal echogenicity
4 types based of US appearance
Hypoechoic compared to liver
Isoechoic compared to liver
Hyperechoic compared to liver
Isoechoic to renal sinus
Hricak H et al. Radiology 1982 ; 144 : 141 – 147.
Fiorini F et al. J Ultrasound 2007 ; 10 : 161 – 167.
Normal
Normal
Pathological
Pathological
Grade 0
Grade I
Grade II
Grade III

16. Kidney parenchyma compared to liver parenchyma
Hypoechoic Isoechoic
Hyperechoic
Fiorini F et al. J Ultrasound 2007 ; 10 : 161 – 167.

17. Congenital normal variants of kidney
• Dromedary hump
• Persistent fetal lobulation
• Prominent column of Bertin
• Junctional parenchymal defect
• Hypoechoic renal sinus
Paspulati RM et al. Ultrasound Clin 2006 ; 1 : 25 – 41.

18. Dromedary hump
Common renal variation
Paspulati RM et al. Ultrasound Clin 2006 ; 1 : 25 – 41.
Focal bulge on lateral border of left kidney
Result from adaptation of renal surface to adjacent spleen
Easily differentiated from renal mass by Doppler

19. Persistent fetal lobulation
Paspulati RM et al. Ultrasound Clin 2006 ; 1 : 25 – 41.
Renal surface indentations between pyramids
May be single or multiple

20. Prominent column of Bertin (PCB)
Mistaken for intrarenal tumor
Paspulati RM et al. Ultrasound Clin 2006 ; 1 : 25 – 41.
Continuity with renal cortex
Similar echo pattern as renal parenchyma
Similar vascular pattern by color & power Doppler

21. Junctional fusion defect
Paspulati RM et al. Ultrasound Clin 2006 ; 1 : 25 – 41.
Mistaken for cortical scar or angiomyolipoma
Continuity with central sinus
by echogenic line
“inter-renicular septum”
Triangular hyperechoic structure
Antero-superior or postero-inferior
surface of kidney

22. Abdominal aorta
• Normal abdominal aorta 1.5 – 2.5 cm
• Ectatic aorta 2.5 – 3 cm
• Aortic aneurysm > 3 cm
• Annual growth of aneurysms 0.33 cm/year
between 4 & 5.5 cm
* Bhatt S et al. Ultrasound Clin 2008 ; 3 : 83 – 91.

23. Cross-section at adrenal glands
Compared to seagull, Y, or V letter
Y-shaped structures lying antero-medial to kidneys
Composed of body & medial & lateral “wing” or “limb”
Tuma J et al. European course book: Genitourinary ultrasound.
European Foundation of Societies of Ultrasound in Medicine & Biology, 2011.

24. US of normal adrenal glands
Documented in 1980 1
1 Dietrich CF et al. Endoscopy 1997 ; 29 : 859 – 864.
2 Jenssen C et al. Ultraschall Med 2010 ; 31: 228 – 250.
With modern equipment (high-resolution) & good training
US can image right gland in 99% & left gland in 70%1
Transcostal scan in LLD
Between RLL, IVC & diaphragm
Right adrenal gland Left adrenal gland
Transverse scan of epigastrium
Dorsal to pancreatic tail & SV

25. Normal adrenal gland / Inverted Y-shape
Hypoechoic right adrenal gland
Horizontally inverted Y-shape
Coronal scan of right upper abdomen through MAL
Wan YL. J Med Ultrasound 2007 ;15 : 213 – 227.

26. 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 US

27. Technical points
• Fasting for at least 6 hours before the exam
• Duration of the examination: 30 – 45 min
• Rare failure: Non-cooperant patient – Gas
• Intestinal preparation: not necessary
Operator-dependent technique
Slow learning curve
Most complex & difficult Doppler examination1
1 Jaeger KA & Uthoff H. Ultraschall Med 2010 ; 31 : 339 – 343.

28. Sites for pulsed Doppler of renal arteries
Aorta
Ostium of main renal artery
Trunk of main renal artery
Hilum of kidney
Upper pole of kidney
Middle pole of kidney
Lower pole of kidney

29. Transverse scan with probe angulations
Main renal arteries
Schäberle W. Ultrasonography in vascular diagnosis. Springer-Verlag, Berlin, 2nd edition, 2011.

30. Norma right renal artery
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
Transverse gray scale image
Right main renal artery
Transverse color Doppler image
Right main renal artery

31. Gray scale alone without color Doppler
Patients with difficulty to hold breath
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
Entire RRA well visualized
Color flash artifact from patient motion may obscure visualization
Better spatial resolution & and faster frame rate
Gray scale image

32. Norma left renal artery
Gray scale image Color Doppler image
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
Proximal main left renal artery Proximal main left renal artery

33. ‘‘banana peel’’ or “Isikoff” view
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
Isikoff MB et al. Am J Roentgenol 1980 ; 134 : 1177 – 1179.
Origins of right & left renal arteries
Gray scale image
Origins of right & left renal arteries
Color Doppler image
Longitudinal transhepatic view in Left lateral decubitus

34. Normal right renal artery
Coronal images of IVC
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
RRA is the only vessel to course laterally under the IVC
Often slightly indents the IVC

35. Two renal arteries or early branching?
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
Longitudinal view of IVC
Two right renal arteries
Transverse view of aorta
Early branching of RRA

36. Longitudinal scan in left lateral decubitus
Multiple renal arteries (25%)
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.

37. Two left renal arteries
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
PSV: 90 cm/sec
Dominant left renal artery
PSV: 60 cm/sec
Accessory left renal artery

38. Axial scan in left lateral decubitus
Using right kidney as acoustic window
Right main renal artery & vein
Color Doppler USSchematic drawing
Meola M et al. J Ultrasound 2008 ; 11 : 55 – 73.

39. Axial scan in right lateral decubitus
Using left kidney as acoustic window
Schematic drawing
Left main renal artery & vein
Color Doppler US
Zubarev AV. Eur Radiol 2001 ; 11 : 1902 – 1915.

40. Pre-caval right renal artery
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.

41. Pre-aortic left renal vein (80 – 95%)
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
Reduction in diameter in pre-aortic segment to IVC
with physiologic acceleration

42. Left renal vein variants
Sidhu R et al. Semin Ultrasound CT MRI 2009 ; 30 : 271 – 288.
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
Retro-aortic LRV (2 – 3%) Circum-aortic LRV (7 – 9%)
Pre & retro-aortic LRV

43. Color Doppler of RRV & retro-hepatic IVC
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
Righ renal vein Inferior vena cava

44. Pulsed Doppler of renal veins
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
Right renal vein
Resembles pulsed Doppler of IVC
Triphasic waveform
Left renal vein
Little modulation
Wall artifact due to systolic peak

45. Limits in visualization of main renal arteries
• Obesity
• Overlying bowel gas
• Dyspnea
• Shadowing from arterial calcifications
• Cardiac arrhythmias
• Poor angle of Doppler insonation
• Accessory renal arteries (small size)
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
Expert sonographers detect 80 – 90% of main RA
CEUS improves success rate to 95%

46. Angle of insonation
Difficulty in case of tortuous or curved renal artery
Correct angleIncorrect angle
Schäberle W. Ultrasonography in vascular diagnosis.
Springer-Verlag, Berlin Heidelberg, 2nd edition, 2011.

47. Adjustment of Doppler control
Low flow settings
• Lowest pulse repetition frequency without aliasing
• Small color box
• Greatest gain without background noise
• Lowest wall filter
• High color priority

48. Normal segmental & interlobar renal arteries
Normal segmental renal arteries (long arrows)
Color Doppler image of the kidney
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
Normal inter-lobar renal arteries (short arrows)

49. Study of intra-renal arteries
Perfusion study / Low PRF
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
Cortical perfusion
Tumoral vascularization

50. Study of intra-renal arteries
Morpho-hemodynamic study
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
Arterio-venous fistula
Pseudo-aneurysm
Intermediate PRF
Renal stones
Vascular calcifications
High PRF

51. Normal kidney
Power Doppler
Increases sensitivity to low flow
Less angle-dependent
Good visualization of the entire renal vascular tree
Zubarev AV. Eur Radiol 2001 ; 11 : 1902 – 1915.

52. Normal pulse Doppler waveform
Renal segmental artery
Sharp systolic upstroke
Low resistance waveform
Continuous forward diastolic flow

53. Pourcelot’s resistive index
RI S – ED / S
Normal 50 – 70 %
Abnormal > 80 %

54. Accleration time (AT)
or Rise time (RT)
• Length of time in sec from
onset of systole to peak systole
• Normal value: < 0.07 second

55. Acceleration Index (AI)
AI =
X (KHz)
Probe frequency (MHz)
Normal value: > 3.5 m/s2
Systolic upslope/transducer frequency

56. Measurement of PSV
Early systolic peak
Am J Roentgenol – Dec 1995
Biphasic with late systolic peak
Monophasic with late systolic peak

57. Early systolic notch
Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
Some normal waveforms have early systolic notch
1. Measuring to point of PSV results in prolonged AT & AI
2. Excellent negative predictive value of stenosis > 60%

58. Extrasystole
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
Correct RI calculated in normal sinusoidal rhythm

59. Spectral Doppler of renal arteries
Normal values
• PSV < 180 cm/sec
• Renal Aortic Ratio (RAR) < 3
• Resistive index (RI) < 0.70
• ∆ RI (right – left) < 0.05
• Acceleration Time (AT) < 0.07 sec
• Acceleration Index (AI) > 3.5 m/s2

60. 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

61. 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

62. 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.

63. 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

64. 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

65. 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

66. 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.

67. 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%

68. 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

69. 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.

70. 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

71. 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

72. 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

73. 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

74. 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

75. 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.

76. 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.

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

78. 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

79. 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.

80. 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

81. 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

82. 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.

83. 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

84. Renal artery thrombosis
• Causes Embolism: most common
Thrombosis – trauma – hypercoagulable state
• Symptoms Acute 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

85. 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

86. 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

87. 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

88. 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

89. 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

90. 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)

91. 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.

92. 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

93. 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

94. 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

95. 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

96. 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)

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

98. 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.

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

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

101. “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

102. 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

103. Arterio-venous communication
Direct communication from artery to vein without capillary bed
• Congenital A-V malformation
25% Multiple large arterial feeding vessels
Numerous A-V communications
• Acquired A-V fistula
75% Single communication of artery & vein
0.3 – 4 % after kidney biopsy
Sidhu R et al. Semin Ultrasound CT MRI 2009 ; 30 : 271 – 288.

104. A-V malformation
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
A-V malformation
with pseudo-aneurismal dilatation
Low resistance arterial flow
Arterialized venous flow
Hydronephrosis or cyst
with calcified wall
Aneurismal dialatation with
peri-vascular artifact

105. A-V fistula
First described in 1962 1
• Cause Iatrogenic (percutaneous procedure) –Trauma
• Clinic Asymptomatic (80%)
Gross hematuria – High output cardiac failure
Thrombo-embolic episodes – RF – HTN
• Evolution Most regress spontaneously in 6 months
Some progress to life-threatening complication
• Rx Asymptomatic: follow-up by Doppler
Symptomatic: embolization
Routine post-biopsy Doppler US & 6 months later
1 Fernstrom I et al. J Urol 1962 ; 88 : 709.
2 J Clin Ultrasound 2008 ; 36 : 377 – 380.

106. Arterio-venous fistula
Feeding artery
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
Perivascular artifact in inferior pole
“confetti phenomenon”
Color Doppler US / High PRF
Low resistance arterial flow
Arterialized venous flow
Feeding artery & draining vein

107. 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

108. Doppler US in nutcracker syndrome
Hilar portion & aorto-mesenteric portion
Cut-off value in supine position 3.8
Cut-off value in upright position 5.5
Fitoz S et al. J Ultrasound Med 2007 ; 26 : 573.
Ratio of A-P diameter of LRV
Ratio of peak velocities of LRV
Aorto-mesenteric portion & hilar portion
Cut-off value in supine position 4.2
Cut-off value in upright position 5.1

109. Nutcracker syndrome / Ratio of A-P diameter
Oblique transverse sonograms
Peker A et al. J Clin Ultrasound 2011 ; 39 : 418 – 421.
Hilar portion: 25 mm
Aorto-mesenteric portion: 2mm
Ratio: 12.5
Supine position
Hilar portion: 24 mm
Aorto-mesenteric portion: 2mm
Ratio: 12
Upright position

110. Nutcracker syndrome / Ratio of peak velocities
Cho BS et al. Nephrol Dial Transplant 2001 ; 16 : 1620 – 1625.
Peak velocity ratio: 6
LRV near hilum
Peak velocity: 19.9 cm/sec
LRV between aorta & SMA
Peak velocity: 99.7 cm/sec

111. Nutcracker syndrome / SMA angle
Peker A et al. J Clin Ultrasound 2011 ; 39 : 418 – 421.
Upright position
14 °
Supine position
33°
Cut-off value
41° in supine position – 21° in upright position

112. 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

113. Doppler in renal Mass
Limited role compared to CT
• Pseudo-tumors Prominent column of Bertin
Persistent fetal lobulation
Dromedary hung
• Renal tumors Tumoral vascularization
CEUS: solid or cystic mass
• Venous invasion Renal veins
IVC
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.

114. Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
Normal interlobular arteries
at periphery of PCB
Prominent column of Bertin (PCB)
Mistaken for intra-renal tumor
Prominent column of Bertin
or mass

115. Vascularization of renal tumors
Jinzaki’s classification
Intratumoral focal vessels
Penetrating vessels
Peripheral vessels
Penetrating & peripheral
Angiomyolipoma
Angiomyolipoma
Carcinoma
Carcinoma
Pattern 1
Pattern 2
Pattern 3
Pattern 4
Jinzaki M et al. Radiology 1998 ; 209 : 543 – 550.

116. Vascularization of renal tumors
Jinzaki M et al. Radiology 1998 ; 209 : 543 – 550.
Pattern 3
Peripheral vessels
Carcinoma
Pattern 4
Penetrating & peripheral vessels
Carcinoma

117. Solid renal mass / CEUS
Hypervascular lesion
CEUS / 34 sec MSCT / arterial phase
Hypervascular lesion
Gray-scale US
Subtle deformation
of renal contour
Clear renal cell tumor at surgery
Setola SV et al. Abdom Imaging 2007 ; 32 : 21 – 28.

118. Bosniak renal cyst classification
Category CT features Significance
I Thin wall, water density & does not enhanced
No septa, calcification, or solid component
Benign
Israel GM & Bosniak MA. Urology 2005 ; 66 : 484 – 488.
II Thin septa with “perceived” enhancement
Fine or slightly thick calcification
High attenuation non-enhancing cyst < 3 cm
Benign
IIF Thick regular septa with “perceived” enhancement
Thick regular wall with “perceived” enhancement
Thick, nodular, & irregular calcification
High attenuation non-enhancing cyst > 3 cm
Likely benign
Follow-up
III Thick smooth or irregular septa
Thick smooth or irregular wall
With measurable enhancement
Some benign
Some malignant
IV Criteria of category III
Enhancing mass independent of wall or septa
Malignant
Cystic carcinoma

119. Cystic renal mass / CEUS
Thin-walled cyst
No septa or solid component
Bosniak category I
CECT scan
Enhancing mural nodule within cyst
Bosniak category IV
CEUS
Park BK et al. Eur J Radiol 2007 ; 61 : 310 – 314.
Renal cell carcinoma after partial nephrectomy

120. Invasion of IVC in RCC
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
Color Doppler US
Localization of upper extremity
of thrombus
Power Doppler US
Tumoral vascularization
of thrombus

121. 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

122. • Nephropathies
• Kidney stones
• Hydronephrosis
• Uretero-pelvic junction obstruction
• Fraley syndrome (Upper calix syndrome)
Miscellaneous indications

123. Renal Doppler in nephropathies
• Acute tubular necrosis
• Tubulo-interstitial nephropathy
• Micro-angiopathy
• Nephro-angiosclerosis
• Diabetic nephropathy
Glomerulo-nephritis
(↑ RI in end stage disease)
Elevated RI Normal RI

124. Diabetic nephropathy
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
Increased resistive index: 0.89
Renal insufficiency

125. Kidney stone / Twinkling artifact
Tchelepi H et al. Am J Roentgenol 2009 ; 192 : 11 – 18.
Twinkling sign from large stone
Presence of small stone
Large stone causing hydronephrosis
Presence of posterior shadowing
Useful for evaluation of small kidney stones
High PRF & gain just below artifact limit

126. Hydronephrosis
RI of LK: 0.45RI of RK: 0.65Hydronephrosis of right UPJ
Δ RI (right – left) > 0.05
Sensibility: 10 – 40%, Specificity > 80%
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
Obstruction without dilatation
Indications Dilatation without obstruction
Hydronephrosis in pregnancy

127. Renal colic in pregnancy
Physiological hydronephrosis or stone?
Retrospective study of 262 patients (2 local hospitals)
Data on clinical presentation, imaging, & interventions
Clinical & laboratory features unhelpful to predict stone
Left-sided colic more likely to indicate stone
Improved accuracy of Doppler in predicting stone (55 – 72%):
Elevated resistive index
Absence of urinary jet
Andreoiu M et al. Urology 2009 ; 74 : 757 – 761.

128. Urinary jet
Obstructed ureter if no jet seen after 15 min of observation
Presence of jet do not exclude incomplete obstruction
Tuma J et al. European course book: Genitourinary ultrasound.
European Foundation of Societies of Ultrasound in Medicine & Biology, 2011.

129. Uretero-pelvic junction obstruction
Most common cause of UT obstruction in children
Multiples proposed factors
Delayed recanalization of fetal ureter
Abnormal development of ureteral muscle
Abnormal ureteral peristalsis
Aberrant vessels or bands
Sivit CJ. Ultrasound Clin 2006 ; 1 : 67 – 75.
Bilateral in 25%

130. Uretero-pelvic junction obstruction
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
Sidhu R et al. Semin Ultrasound CT MRI 2009 ; 30 : 271 – 288.
Hilar artery seen in 30 – 45% of patients
Crossing vessel usually located anterior to UPJ obstruction

131. Fraley syndrome / Upper calyx syndrome
Vascular compression of superior calyx
Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
IV pyelography
Superior calyx obstruction
due to extrinsic compression
Color Doppler US
Segmental artery crossing
the dilated calyx
CT Angiography before tt: polar nephrectomy – reimplantation

132. References
Springer-Verlag – 2011
Hélénon O et al. EMC-Radiologie
2005 ; 2 : 367 – 412.
EFSUMB – 2011

133. Thank You