Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Doppler ultrasound of the kidneys

85,995 views

Published on

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

Published in: Health & Medicine, Business

Doppler ultrasound of the kidneys

  1. 1. Doppler ultrasound of the kidneys Samir Haffar M.D. Assistant Professor of Internal Medicine
  2. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 16. Kidney parenchyma compared to liver parenchyma Hypoechoic Isoechoic Hyperechoic Fiorini F et al. J Ultrasound 2007 ; 10 : 161 – 167.
  17. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 29. Transverse scan with probe angulations Main renal arteries Schäberle W. Ultrasonography in vascular diagnosis. Springer-Verlag, Berlin, 2nd edition, 2011.
  30. 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. 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. 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. 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. 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. 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. 36. Longitudinal scan in left lateral decubitus Multiple renal arteries (25%) Moukaddam H et al. Ultrasound Clin 2007 ; 2 : 455 – 475.
  37. 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. 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. 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. 40. Pre-caval right renal artery Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412.
  41. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 52. Normal pulse Doppler waveform Renal segmental artery Sharp systolic upstroke Low resistance waveform Continuous forward diastolic flow
  53. 53. Pourcelot’s resistive index RI S – ED / S Normal 50 – 70 % Abnormal > 80 %
  54. 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. 55. Acceleration Index (AI) AI = X (KHz) Probe frequency (MHz) Normal value: > 3.5 m/s2 Systolic upslope/transducer frequency
  56. 56. Measurement of PSV Early systolic peak Am J Roentgenol – Dec 1995 Biphasic with late systolic peak Monophasic with late systolic peak
  57. 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. 58. Extrasystole Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412. Correct RI calculated in normal sinusoidal rhythm
  59. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 77. Abdominal aortic aneurysm & renal arteries Zubarev VZ. Eur Radiol 2001 ; 11 : 1902 – 1915. Aneurysm arises below origin of both renal arteries
  78. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 97. Aneurysm of left renal artery Gao J et al. Clinical Imaging 2006 ; 30 ; 140 – 142. Gray-scale US Color Doppler US Angiography
  98. 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. 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. 100. Pseudo-aneurysm Sampling at neck To-and-fro waveform “To” Systole “Fro” Diastole
  101. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 122. • Nephropathies • Kidney stones • Hydronephrosis • Uretero-pelvic junction obstruction • Fraley syndrome (Upper calix syndrome) Miscellaneous indications
  123. 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. 124. Diabetic nephropathy Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412. Increased resistive index: 0.89 Renal insufficiency
  125. 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. 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. 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. 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. 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. 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. 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. 132. References Springer-Verlag – 2011 Hélénon O et al. EMC-Radiologie 2005 ; 2 : 367 – 412. EFSUMB – 2011
  133. 133. Thank You

×