Doppler us of the kidneys 2

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Renal Doppler Indications and Detection of Pathologies

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Doppler us of the kidneys 2

  1. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 18. Abdominal aortic aneurysm & renal arteries Zubarev VZ. Eur Radiol 2001 ; 11 : 1902 – 1915. Aneurysm arises below origin of both renal arteries
  19. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 38. Aneurysm of left renal artery Gao J et al. Clinical Imaging 2006 ; 30 ; 140 – 142. Gray-scale US Color Doppler US Angiography
  39. 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. 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. 41. Pseudo-aneurysm Sampling at neck To-and-fro waveform “To” Systole “Fro” Diastole
  42. 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

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