Doppler us of the kidneys 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 ultrasound

PheochromocytomaUncommon – 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

Micronodular cortical hyperplasia of right adrenal glandStructure measuring approximately 5 mm

& isoechoic to adrenal cortex

Conn’s sydrome / adrenal hyperplasia

Jenssen C et al. Ultraschall Med 2010 ; 31: 228 – 250.

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

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


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

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.


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%

Renal artery stenosis / Direct criteriaNon-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

Renal artery stenosis / Direct criteria

PSV: 275 cm/secHigh-grade stenosis

Aliasing in left renal artery

Schäberle W. Ultrasonography in vascular diagnosis.

Springer-Verlag, Berlin Heidelberg, 2nd edition, 2011.

Renal artery stenosis / First Generation CEUS


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

PSV: 293 cm/sec – RI : 0.91Controversial indication of PTA2

Aliasing in left renal arteryRetro-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

Creatinine clearance after correction of RASaccording 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

Renal artery stenosis / Renal Aortic Ratio


Small right kidney (8.4 cm) PSV (aorta): 102 cm/s

PSV (RRA): 465 cm/s High grade stenosis of RRA

RAR: 4.5

Renal artery stenosis / Indirect criteria

Schäberle W. Ultrasonography in vascular diagnosis.Springer-Verlag, Berlin, 2nd edition, 2011.

PSV: 85.7 cm/sEDV: 47.2 cm/s

RI: 0.64

Left renal hilum Right renal hilum

PSV: 125 cm/secEDV: 58.1 cm/s

RI: 0.75

Δ RI (right – left) > 0.05 → RA stenosis in side of lower RI

Renal artery stenosis / Tardus-Parvus waveSevere stenosis (> 85 % diameter reduction)

Tardus: Longer rise time

Parvus: Low PSV

Freeman SJ. Ultrasound 2004 ; 12 : 69 – 74.

Tardus-Parvus wave

• Mimics Abdominal coarctationWilliam syndromeAortic/mitral valve diseaseLeft ventricle dysfunctionCV medications: after-load reducers

• Exaggerating 25 mg captopril 1 hour before exam

• Minimizing Age – HTN – DM (vessel compliance)


Abdominal aortic aneurysm & renal arteries

Zubarev VZ. Eur Radiol 2001 ; 11 : 1902 – 1915.

Aneurysm arises below origin of both renal arteries

Fibromuscular dysplasiaMoniliform aspect of RRA

Typical FMD in middle third of RRA


PSV 250 cm/sec

No parallelism of RRA walls

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.

Renal artery dissectionFlank pain & hematuria – Stenotic or occlusive lesion


Interruption of LRA « bec de flûte »

Associated thrombosis of LRV

Occlusion of LRA at its origin

Complete necrosis of LK

Coarctation of abdominal aorta

Severe hypertension in a 6-year-old boy


Bilateral & symmetric

tardus parvus waveformSagital view of aorta

Severe narrowing at level of CA & SMA

Guidelines for diagnosis of RAS

• Recommended as screening testDuplex US followed by CT angiography (except RF) & MR angiography

• Not recommended as screening testCaptopril renal scintigraphy Plasma renin activityCaptopril testSelective renal vein renin measurements

Hirsch AT et al. J Am Coll Cardiol 2006 ; 47 : 1239 – 1312.







Nutcracker syndrome

Renal mass


Renal artery thrombosis

• Causes Embolism: most commonThrombosis – 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

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

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

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







Nutcracker syndrome

Renal mass


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

Acute renal vein thrombosis

Absence of color signalin 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)

Acute renal vein thrombosis / Poor outcome

• Reduced perfusion at diagnosis

• Subcapsular fluid collections

• Profoundly hypoechoic & irregular renal pyramids

• Patchy cortical echotextureLikely reflecting cortical infarction & hemorrhage




Severely decreased renal perfusion

Right kidney

Normal perfusion for comparison

Left kidney

Subcapsular fluid collections

Hypoechoic & irregular pyramidsPatchy hypoechoic areas in cortex



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.


Capsular collateral veins

Linear calcifications in parenchyma







Nutcracker syndrome

Renal mass


Renal artery aneurysmsExtraparenchymal 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)

Aneurysm of left renal artery

Gao J et al. Clinical Imaging 2006 ; 30 ; 140 – 142.

Gray-scale US Color Doppler US

Angiography

Micro-aneurysmsContraindication 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


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

Pseudo-aneurysm

Sampling at neck To-and-fro waveform

“To” Systole “Fro” Diastole

“to and fro waveform”within neck of the lesion

Cystic lesion in middle of RKBi-directional flow

“yin -yang pattern”

Rashid M et al. Emerg Radiol 2007 ; 14 : 257 – 260.

Renal pseudo-aneurysm

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Date post:	07-May-2015
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Doppler us of the kidneys 2

Education