vascular ultrasound
DESCRIPTION
Fundamentals of Vascular Ultrasound. Looking at the basics of carotid, lower extremity arterial, renal, celiac, SMA studies, as well as touching on venous insufficiency. Part I of series.TRANSCRIPT
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FUNDAMENTALS FUNDAMENTALS OFOF
VASCULARVASCULARULTRASOUNDULTRASOUND
part onepart one
FUNDAMENTALS FUNDAMENTALS OFOF
VASCULARVASCULARULTRASOUNDULTRASOUND
part onepart one
steve henao mdsteve henao mdnew mexico heart institutenew mexico heart institute
steve henao mdsteve henao mdnew mexico heart institutenew mexico heart institute
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CarotidCarotidCarotidCarotid
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•Carotid disease accounts
for 25%25% of all strokes
•detection by physical
exam is poorpoor
•stroke is the result of
embolizationembolization
•lesions are typically at
the posterolateral wall of
the internal carotid
artery
•Carotid disease accounts
for 25%25% of all strokes
•detection by physical
exam is poorpoor
•stroke is the result of
embolizationembolization
•lesions are typically at
the posterolateral wall of
the internal carotid
artery
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CAROTID ULTRASOUNDCAROTID ULTRASOUND
• The most common clinical application is for the detection of proximal ICA atherosclerotic plaque and estimation of stenosis severity.
• The extent of ICA bifurcation diameter reduction predicts the risk for stroke and thus assists clinicians in identifying patients who may benefit from carotid intervention (endarterectomy, stent angioplasty) based on clinical trial results
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Scanning the ICAScanning the ICA
grayscale, color Doppler and Pulse-wave Doppler
proximal, middle, and distal portions
>50% stenosis of the proximal ICA renders flow turbulent in the distal ICA
severe stenosis yields parvus et tardus waveforms
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proxmial ICA stenosis severity is established proxmial ICA stenosis severity is established on the baisis of :on the baisis of :
GRAYSCALE APPEARANCE
PEAK SYSTOLIC VELOCITY OF THE ICA
END DIASTOLIC VELOCITY OF THE ICA
PEAK SYSTOLIC VELOCITY OF THE COMMON CAROTID ARTERY
velocity ratios
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Grayscale imaging is Grayscale imaging is performed to localize performed to localize
and characterize and characterize plaque severity as:plaque severity as:
Grayscale imaging is Grayscale imaging is performed to localize performed to localize
and characterize and characterize plaque severity as:plaque severity as:
•less than 50%less than 50%•greater than or equal to 50%greater than or equal to 50%
•occlusionocclusion
•less than 50%less than 50%•greater than or equal to 50%greater than or equal to 50%
•occlusionocclusion
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Color Doppler flow Color Doppler flow mapping is usefulmapping is useful Color Doppler flow Color Doppler flow mapping is usefulmapping is useful
to define the lumen- to define the lumen- because hypoechoic because hypoechoic
plaque and restenosis plaque and restenosis material material may be may be
inapparent by regular inapparent by regular grayscale grayscale
to define the lumen- to define the lumen- because hypoechoic because hypoechoic
plaque and restenosis plaque and restenosis material material may be may be
inapparent by regular inapparent by regular grayscale grayscale
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assessment of stenosisassessment of stenosis
• angiographyangiography is the traditional gold standard
• ultrasoundultrasound has developed steadily with sufficiently reliable preoperative results
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assessment of stenosisassessment of stenosis
• there arethere are MANYMANY differences in the carotid reference standard to establish percent stenosis
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stenosis ‘standards’stenosis ‘standards’
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Consensus panel grayscale and doppler ultrasound criteria for diagnosis of internal
carotid artery stenosis (2003)
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validating the consensus document (2011)
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“receiver operatingreceiver operatingcharacteristiccharacteristic”
The ROC curve was first developed by electrical engineers and radar engineers during World War II for detecting enemy objects in battlefields and was soon introduced to psychology to account for perceptual detection of stimuli.
ROC analysis since then has been used in medicine, radiology, biometrics, and other areas for many decades and is increasingly used in machine learning and data mining research.
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Fig 1
Source: Journal of Vascular Surgery 2011; 53:53-60 (DOI:10.1016/j.jvs.2010.07.045 )
Copyright © 2011 Society for Vascular Surgery Terms and Conditions
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Fig 2
Source: Journal of Vascular Surgery 2011; 53:53-60 (DOI:10.1016/j.jvs.2010.07.045 )
Copyright © 2011 Society for Vascular Surgery Terms and Conditions
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Fig 3
Source: Journal of Vascular Surgery 2011; 53:53-60 (DOI:10.1016/j.jvs.2010.07.045 )
Copyright © 2011 Society for Vascular Surgery Terms and Conditions
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analysis
the parameter with the highest Pearson correlate to angiography was the PSVPSV (0.813), in contrast to both EDV (0.7) and ICA/CCA PSV ratios (0.57, P < .0001)
A PSVPSV of >230 cm/s was the most sensitive in the diagnosis of 70% to 99% stenosis, and adding other parameters (EDV or ratios) did not improve the overall accuracy
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analysis
Using a PSVPSV of >230 cm/s with an EDVEDV of >100 cm/s or a systolic ratiosystolic ratio of >4 would improve the PPV to 99% and the specificity to 97%
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analysis
the ICA/CCA PSV ratio and the ICA EDV are useful parameters when the ICA PSV may not be representative of the extent of carotid disease because of technical or clinical factors:
• presence of contralateral high-grade stenosis or occlusionpresence of contralateral high-grade stenosis or occlusion
• discrepancy between visual assessment of the carotid discrepancy between visual assessment of the carotid plaque and the ICA PSVplaque and the ICA PSV
• elevated CCA velocity, low cardiac output, or elevated CCA velocity, low cardiac output, or hyperdynamic cardiac statehyperdynamic cardiac state
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analysis
patients with low cardiac low cardiac output would have a low ICA PSV, which is disproportionate when compared with the ICA/CCA PSV ratio.
In these situations, the clinician must rely on the presence of the plaque and perhaps the ICA/CCA ratio rather than the absolute ICA PSV
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carotid endarterectomythe PSV threshold of 230 cm/s for detecting ≥70% stenosis can be used before CEA for symptomaticsymptomatic patients since surgery has been proven to be beneficial, even for ≥50% symptomatic stenosis
A higher PSV (eg, ≥280 cm/s), which has a PPV of 97%, or a PSV of >230 cm/s with an EDV of >100 cm/s, or a systolic ratio of >4 (PPV of 99%) may be considered in asymptomatic patientsasymptomatic patients
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POST-CAROTID STENTING CRITERIA
Interpretation of high-grade (>75% to 80%) in-stent stenosis should be based on elevation of EDV beyond 125 to 140
cm/second
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SUMMARY(2014)
The variability in carotid stenosis interpretationvariability in carotid stenosis interpretation across accredited facilities undermines the usefulness of this important diagnostic modality.
The IAC Vascular Testing Board of Directors feels that more standardization of carotid duplex ultrasound diagnostic criteria will address these concerns and will enhance the accuracy, reproducibility, portability and value of duplex sonography for the diagnosis of carotid disease.
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lower extremitylower extremityarterialarterial
lower extremitylower extremityarterialarterial
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Indications for Indications for Duplex Arterial TestingDuplex Arterial Testing
• Acute limb ischemiaAcute limb ischemia as a result of arterial thrombosis caused by atherosclerosis, thromboembolism, trauma, or peripheral aneurysm
• Chronic arterial occlusion/stenosis with intermittent intermittent claudicationclaudication or an abnormal (<0.9) ankle-brachial index (ABI)
• Chronic arterial occlusion and threatened limb loss caused by rest pain, ischemia, ulceration, or gangrene (i.e., critical limb critical limb ischemiaischemia)
• Aneurysmal diseaseAneurysmal disease, including false aneurysm after catheter-based interventions, or screening for abdominal aortic aneurysm (AAA) in “selected,” high-risk patients
• SurveillanceSurveillance for hemodynamic failure of arterial interventions (percutaneous transluminal angioplasty [PTA], stent-grafts, bypass grafting, dialysis access procedures)
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criteria for classifyingcriteria for classifyingperipheral artery lesionsperipheral artery lesions
triphasic waveform
no spectral broadening
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criteria for classifyingcriteria for classifyingperipheral artery lesionsperipheral artery lesions
triphasic with minimal spectral broadening
PSV increased PSV increased <30%<30% relative to adjacent proximal segment (<150 cm/s)
proximal and distal waveforms remain normal
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criteria for classifyingcriteria for classifyingperipheral artery lesionsperipheral artery lesions
Triphasic wave usually maintained
reverse flow component may be diminished
spectral broadening prominent
filling in of clear area under the systolic peak
PSV increased 30 - 100%PSV increased 30 - 100% relative to the adjacent proximal segment (150-200cm/s)
proximal and distal waveforms remain normal
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criteria for classifyingcriteria for classifyingperipheral artery lesionsperipheral artery lesions
monophasic wave with loss of reverse flow component and forward flow throughout cardiac cycle
extensive spectral broadening
PSV >100%PSV >100% relative to proximal segment (>200-300cm/s)
distal wave monophasic with reduced systolic velocity
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criteria for classifyingcriteria for classifyingperipheral artery lesionsperipheral artery lesions
• no flow detected
• distal waveforms monophasic with reduced systemic velocities
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Vein Bypass Evaluation
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CharacteristicsCharacteristicsofof
vein graft stenosisvein graft stenosis
Graft Stenosis: Less Than 20% Less Than 20%
• Velocity ratio less than 2
• Mild turbulence in systole
• PSV less than 200 cm/sec
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CharacteristicsCharacteristicsofof
vein graft stenosisvein graft stenosis
Graft Stenosis: 20% to 50%20% to 50%
• Velocity ratio greater than 2
• Turbulence throughout
• PSV less than 200 cm/sec
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CharacteristicsCharacteristicsofof
vein graft stenosisvein graft stenosis
Graft Stenosis: 50% to 75%50% to 75%
• Velocity ratio greater than 2.5
• Severe turbulence with reversed flow components
• PSV greater than 200 cm/sec
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CharacteristicsCharacteristicsofof
vein graft stenosisvein graft stenosis
Graft Stenosis: 75% to 99%75% to 99%
Velocity ratio greater than 3.5
End-diastolic velocity in flow jet greater than 100 cm/sec
PSV greater than 300 cm/sec
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CharacteristicsCharacteristicsofof
vein graft stenosisvein graft stenosis
Impending Graft ThrombosisImpending Graft Thrombosis
• Velocity ratio greater than 3.5
• PSV less than 50 cm/sec
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Risk Stratification for graft thrombosis based Risk Stratification for graft thrombosis based on vascular lab testing dataon vascular lab testing data
approximately 20% of infrainguinal vein bypasses will have a category I or II stenosis identified within the
first year after grafting
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AORTAAORTAAORTAAORTA
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AortaAorta
Normal Infrarenal abdominal aorta 2cm (range, 1.4 to 3 cm)
‘dilated’ = AP diameter 3 to 3.5 cm
‘aneurysm’ = > 3.5 cm, especially if mural thrombus is imaged
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AORTAAORTA
Reporting should include:
• morphology (saccular, fusiform)
• extent
• presence of mural thrombus or dissection
• outside wall-to-wall diameter
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AORTAAORTA• typical growth rate for AAA= 3 to
4 mm/year
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RENAL RENAL arteryarteryRENAL RENAL arteryartery
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Renal Artery Duplex
HTNHTN and sudden deterioration in renal deterioration in renal functionfunction are the most common indications
• atherosclerosisatherosclerosis 95%
• 1 to 6% of HTN patients, but most common cause of HTN in pts >50
• men affected 2x women
arterial fibrodysplasiaarterial fibrodysplasia 5%
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RARRAR
• interpretation of renal artery stenosis is based on the maximum PSV obtained from the aorta above the renal arteries (at the level of the SMA) and the renal artery itself
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renal interpretation& reporting
Normal Study:
• PSV: 80 ± 20 cm/second
• Renal-to-aortic PSV ratio (RARRAR): less than 3.5
• Normal waveform: biphasicbiphasic
• No focal velocity increase
• Low resistance waveformLow resistance waveform (RI <0.8)
• - similar to internal carotid
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renal interpretation& reporting
Less Than 60% Diameter Reduction
• Low resistanceLow resistance waveform
• RARRAR: less than 3.5
• PSV: less than 180 cm/sec
• Focal velocity increase
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renal interpretation& reporting
Greater Than 60% Diameter Reduction
• RARRAR: greater than 3.5
• True post-stenotic turbulence
• Focal PSV increase greater than 180 cm/sec
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NORMAL KIDNEYNORMAL KIDNEY
• LENGTH: 9 TO 13 CM
• WIDTH: 4 TO 6 CM
• REASONABLE DIFFERENCE IN LENGTH BETWEEN KIDNEYS: 1 CM
• length difference greater than 1 cm suggests that the smaller kidney is abnormal
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renalrenalspectral velocity
criteria
• biphasic: normal (similar to internal carotid artery)
• triphasic: highly abnormal
• monophasic: highly abnormal, consistent with distal occlusion or significant renal malfunction
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renovascular resistance
RI: measured in the body of the kidney vasculature to assess renal resistance and suggest perfusion
• RI < 0.7 NORMAL
• RI 0.7 to 0.8 questionably elevated
• RI >0.8 ABNORMAL
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CELIACCELIACSMASMAIMAIMA
CELIACCELIACSMASMAIMAIMA
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Celiac
NORMAL
• PSV = 90 to 110 cm/second
• low-resistance flow pattern
• no plaque visualized
• laminar and forward flow throughout diastole
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celiac
< 70% Stenosis
• PSV: < 200 cm/second
• EDV: < 55 cm/ second
• resistive index similar to that of the ICA
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celiac
> 70% stenosis
• PSV > 200 cm/second
• EDV > 55 cm/ second with retrograde hepatic artery flow
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SMA
NORMAL
• PSV: 95 to 150 cm/second
• high-resistance flow pattern in fasting state
• EDV > 0 after a meal
• no plaque visualized
• laminar and forward flow throughout diastole
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SMA
< 70% Stenosis
• PSV <300 cm/second
• EDV < 45 cm/ second with diastolic flow reversal in the distal SMA
• plaque visualized
• color doppler evidence of focal and post-stenotic turbulence
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SMA
> 70% Stenosis
• PSV > 300 cm/second
• EDV > 45 cm/ second with loss of diastolic flow reversal
• mesenteric - aorta ratio > 3
• velocity spectra change with test meal
• increase in PSV at sites of stenosis with damping of the distal waveform
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LOWER EXTREMITYLOWER EXTREMITYVENOUSVENOUS
LOWER EXTREMITYLOWER EXTREMITYVENOUSVENOUS
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VENOUS REFLUX
• a prospective study has demonstrated that the acceptable physiologic flow reversal is different for different veins
Jeanneret C, Labs KH, Aschwanden M, et al: Physiological reflux and venous diameter change in the proximal lower limb veins during a standardised Valsalva manoeuvre. Eur J Vasc Endovasc Surg 1999; 17:398-403.
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VENUS REFLUX
the theory supporting this concept is that larger veins have fewer valves
• the expected time for the valve leaflets to come together is longer than that for smaller, shorter veins
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venous reflux
REFLUX = 1000 milliseconds
• common femoral
• femoral
• popliteal
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venous reflux
REFLUX = 500 milliseconds
• superficial
• deep femoral
• deep calf axial
• muscular veins
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venous reflux
REFLUX = 350 milliseconds
• perforating veins
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FUNDAMENTALS FUNDAMENTALS OFOF
VASCULARVASCULARULTRASOUNDULTRASOUND
part onepart one
FUNDAMENTALS FUNDAMENTALS OFOF
VASCULARVASCULARULTRASOUNDULTRASOUND
part onepart one
steve henao mdsteve henao mdnew mexico heart institutenew mexico heart institute
steve henao mdsteve henao mdnew mexico heart institutenew mexico heart institute