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OU NeurologyOU Neurology
Introduction to Carotid Ultrasound and Transcranial Doppler
Ultrasound
Ryan Hakimi, DO, MSDirector, Critical Care Neurology
Assistant ProfessorDepartment of Neurology
The University of Oklahoma Health Sciences CenterJanuary 16, 2015
OU NeurologyOU Neurology
Disclosures
Many of the slides have been adapted from slides presented at the American Society for Neuroimaging Annual Meetings by my mentors
FINANCIAL DISCLOSURE Nothing to disclose
UNLABELED/UNAPPROVED USES DISCLOSURE Nothing to disclose
Andre Alexandrov, MD Zsolt Garami, MD Charles Tegeler, MD Alex Razumovsky, PhD
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Objectives Review the basic principles of carotid ultrasound (CUS)
and transcranial Doppler ultrasound (TCD) Illustrate the process of plaque morphology and
assignment of range of carotid stenosis Illustrate the process of determining vasospasm by TCD Discuss some of the current applications of TCD
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Principles of Ultrasound
Blood flow velocity through a cross sectional area of a particular vessel (cm/s)
Blood flow velocity is directly related to Doppler shiftIf you measure the Doppler shift you can
derive the blood flow velocity Carotid ultrasound and transcranial Doppler
ultrasound can accomplish this
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Ultrasound Physics
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Carotid Ultrasound
IndicationsIschemic stroke or TIAAssessment of carotid bruitAssessment of carotid stenosis or occlusionPre-operative assessment for cardiovascular
surgeryPost carotid endarterectomy or stenting
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Principles of Carotid Duplex
Duplex (B-mode and Doppler)B-mode (brightness mode)
Grayscale, used for visualization of structures and assessment of plaque morphology
• Hyperechoic (bright white: bone, calcium), causes a shadow posterior to it
• Hypoechoic (black or grey: thrombus)
Doppler velocities (peak systolic and end diastolic) Used to determine the direction of blood flow Used to estimate the range of stenosis Each lab should have own validated parameters of the
velocities to be used for assignment of stenosis, not just use published values
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Assignment of Carotid Stenosis
Carotid Artery Stenosis: Gray-Scale and Doppler US Diagnosis—Society of Radiologists in Ultrasound Consensus Conference Grant et al., 2003
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Transverse Right ICA B-Mode
common carotid artery
(Transverse Right Proximal Common Carotid Artery)
Skin surface
internal jugular vein
muscle
Fat and subcutaneous tissue
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Longitudinal Right ICA B-mode Plaque
(Longitudinal Right Proximal Internal Carotid Artery)
Focal irregular, heterogeneous plaque in the R Prx ICA
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Right ICA B-mode with Color Doppler
Patient’s Head
Flow(away from probe)
- Flow(away from probe)
+ Flow(toward probe)
(Right Proximal Internal Carotid Artery)
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Right ICA Doppler Velocities
(Right Proximal Internal Carotid Artery)
Cardiac irregularity
+ Flow(away from probe)- Flow(away from probe)
Patient’s Head
Flow(away from probe)
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Report
Focal plaque in the right internal carotid artery No hemodynamically significant stenosis demonstrated in the right internal
carotid artery. High resistance with focal plaque in the right internal carotid artery Cardiac irregularity was noted
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Longitudinal Left CCA B-mode Plaque
(Longitudinal Left Mid Common Carotid Artery)
Plaque with fibrous cap and lipid rich core
Hyperechoic plaque with posterior acoustic shadowing
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Longitudinal Left CCA B-mode Plaque
Heterogeneous plaque with posterior acoustic shadowing
(Longitudinal Left Distal Common Carotid Artery)
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Longitudinal Left ICA Color Doppler
Noise(sample volume picking up multiple velocity jets)
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Carotid US vs Transcranial Doppler US
Carotid UltrasoundDirectly visualize the vesselStenosis determined by peak systolic velocity
TCDBlind insonationUses mean velocity
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Transcranial Doppler Ultrasound
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TCD Wave
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TCD Spectra
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Pulsatility Indices
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Pulsatility Indices
Low PIAVMlow ejection fractionaortic regurgitation
High PI: intracranial atherosclerosis increased intracranial pressure
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Insonation of Brain
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TCD use in Carotid Occlusive Disease
Allows for evaluation of:Collateral flowCerebral embolismPoor vasomotor reserve i.e. progression of
carotid stenosis
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TCD use in Carotid Occlusive Disease
Slide courtesy Z. Garami, MD
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Risk of Ipsilateral Stroke: Number of Activated Collaterals (ACA, PCOM, OA)
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Subarachnoid Hemorrhage Detection of vasospasm
Clinical exam (usually somnolence or non-focal symptoms), not very sensitive
Daily TCD (non-invasive, 90% sensitivity, often precedes clinical vasospasm)
TCD or CTA can be used to screen for “plasty-able” lesions
Images from 1. http://www.spencertechnologies.com/products.html#thumb 2. www.viswiki.com/en/Transcranial_doppler, 3. http://depts.washington.edu/uwtcdlab/images/tcd/tcd3_lg.gif all accessed on 1/24/2010 4. Cerebrovascular Ultrasound in Stroke Prevention
and Treatment
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Thresholds for Anterior Circulation Vasospasm
Should be validated at the given centerMild vasospasm 120-140 cm/s, Lindegaard
Ratio (MCA velocity/extracranial ICA) 3-4Moderate vasospasm 140-180 cm/s,
Lindegaard Ratio (MCA velocity/extracranial ICA) 4-6Severe vasospasm >200 cm/s, Lindegaard
Ratio (MCA velocity/extracranial ICA) >6Less reliable in posterior circulation (due to
greater anatomic variance)
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Data on TCD Monitoring
Courtesy Mauro Oddo, MD
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Subarachnoid Hemorrhage Triple-H therapy (hypertension, hypervolemia,
hemodilution) Introduced in 1970’s to prevent delayed cerebral
ischemia from vasospasmProphylactic triple-H (in absence of vasospasm) does
not prevent vasospasm (Treggiari et al. J. Neurosurg 2008)
Double-H therapy (hypertension and hypervolemia as hemodilution is consequence of hypervolemia)Must be individualized and titrated to clinical exam
and TCDCan result in pulmonary edema, hyponatremia, MI,
etc.
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Brain Death
Uniform Determination of Death ActLegally acknowledged brain death as a
mechanism of deathDefined death as:
Irreversible cessation of circulatory and respiratory functions OR
Irreversible cessation of all functions of the entire brain, including the brain stem
1. Guidelines for the determination of death: report of the medical consultants on the diagnosis of death to the President’s commission on the ethical problems in medicine and biochemical and behavioral research. JAMA 1981;246:2184-2186.
2. Uniform Determination of Death Act, 12 uniform laws annotated 589 (West 1993 West suppl 1997)
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AAN recommendations on use of ancillary testing
AAN Clinician Guideline Supplement: Ancillary Testing; Update: Determining Brain Death in Adults. 2010.
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Diagnosis of Patent Foramen Ovale (PFO)
Slide courtesy Alex Razumovsky, PhD
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Diagnosis of Patent Foramen Ovale (PFO)
PFO is a residual channel between the right and left atrium which originally allowed oxygenated placental blood to pass from the right to left atrium bypassing the fetal lungs
Usually closes by age 2, but can persist in 25-30% of the general population
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Diagnosis of PFO by TCD
Agitated saline studyMonitor the MCA
Slide courtesy Z. Garami, MD
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Diagnosing subclavian steal by TCD
Image the vertebral arteryIschemic cuff test
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Subclavian Steal Syndrome
Slide courtesy Z. Garami, MD
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Questions
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Thank you