Transcript Document

Introduction to
Transcranial Doppler / TCD
TCD and TCDI Principles
Objectives
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List clinical applications for TCD
Identify the architecture of the Circle of Willis
Recognize data used for TCD interpretation
Describe advantages of TCD imaging
Identify TCD features of the MicroMaxxTM system
Cervical Vascular Anatomy
Cerebrovascular Anatomy
Transcranial Doppler
• Provides functional information about
physiological flow states
• Identifies anatomical location
• Demonstrates the extent and degree of severity
of various abnormalities
American Academy of Neurology
Position Statement (1989)
• TCD is of established value in assessing
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Servere stenosis of major basal arteries (>65%)
Collateral circulation
Vasoconstrictions
AVM’s
Brain Death
TCD Utilization
• Cardiology
– Pre-operative extracranial carotid evaluation
– Assessment of Intracranial collateral pathways
– Emboli Monitoring
TCD Utilization
• Neuroradiologists
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Trauma
Tumor/space occupying lesion
Aneurysm detection
AVM’s
Vasospasm
Brain death
TCD Utilization
• Vascular and Neurology Specialists
– Assessment of intracranial collateral pathways in
patients with extracranial carotid disease
– Evaluation of response to revascularization
– Evaluation of intracranial vascular lesion
– Documentation of Subclavian Steal Syndrome
– Assessment of Vertebrobasilar system
– Monitor and manage Sickle Cell disease
Understanding
Non-Imaging TCD
TCD-Non-Imaging TCD
• Trace or map out the vessels only using the
Doppler spectrum
• Record bilateral depths and means equally
• Compare vessels side to side, close to exact
sample depths
• Non-imaging is successful in 90% of the patient
population
TCDI-Imaging TCD
• Advantages
– Increased confidence in identification of vessels and
pathology
– Identification of anatomical variations
– Quick identifications of abnormal flow patterns
– Possibility of angle corrections
• Disadvantages
– Obtainable in 75-80% of the patient population
A complete Circle of Willis is
present in 50% of the
population
A perfect configuration of the
Circle of Willis is present in
only 18% of the population
Vessel Identification Non-Imaging
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Depth of Sample Volume
Direction of flow
Angle of transducer
Traceability of vessel
Spatial relationships between vessels
Response to CCA oscillations or compressions
All of these are utilized to “prove” what vessel you are
insonnating
Vessel Identification Imaging
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Depth of Sample Volume
Direction of flow
Angle of transducer
Traceability of vessel
Spatial relationships between vessels
No need to “prove” vessels, because you can easily see
where the vessel lie within the image
Normal Values (Mean Velocities)
VesselsMean
MCA(M1)
ACA
PCA
Siphon
OA
Basilar
Vertebral
t-ICA
D-ICA
Depth
62+12
50+11
39+10
47+14
21+ 5
41+10
38+10
39+ 9
37+ 9
Flow Direction
30-67mm
Towards
60-80mm
Away
55-75mm
Towards
60-80mm
Towards/Away
40-60mm
Towards
>80
Away
60-85mm
Away
50-60mm
Away
35-70mm
Away
Investigator Variability
Author
Aaslid
DeWitt
Gromlimund
Harders
Ringlestein
Zanette
Sorteberg
Russo
MCA
62+12
62+12
57+15
65+17
55+12
56+12
73+11
65+13
ACA
51+12
52+12
49+15
50+13
50+11
50+10
58+9
48+20
PCA
44+11
42+10
37+10
40+9
39+10
43+7
43+10
35+18
Physiologic Factors
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Age
Gender
Hematocrit
Fever
Hypoglycemia
Carbon Dioxide
Heart Rate/Cardiac Output/Blood Pressure
Brain Activity
Prior to TCD Exam
• What is going on with the patients
cerebrovascular and cardiovascular system?
• Scan the patients carotid or have a recent carotid
exam report
• Find out if patient has had a recent
echocardiogram
Prior to TCD Exam
Normal Exam
Prior to TCD Exam
Abnormal Exam
Prior to TCD Exam
Previous Patient Report
Prior to TCD Exam
Cardiac Mass
TCD: Normal Direction of Flow
TCD Imaging Orientation
TCD & TCDI Protocol and Interpretation
Access Windows
Transorbital
Window
Transtemporal
Window
Submandibular
Window
Transoccipital/
Suboccipital
Window
TCDI-Transtemporal Window
Boney Landmarks
Lesser wing of the
Sphenoid Bone
Petrous Ridge
Lesser Wing
Of the
Sphenoid Bone
Petrous Ridge
Foramen Lacerum
Foramen Lacerum
Foramen Lacerum
TCDI-Transtemporal Window
Segments recorded in a complete exam
• MCA ( Prox, Mid, Distal )
• ACA
• PCA ( P1 and P2 )
• tICA (Terminal ICA)
TCDI- Submandibular Window
Segments recorded in a complete exam
• Distal ICA ( Internal Carotid Artery )
TCDI- Suboccipital Window
Segments recorded in a complete exam
• Vertebral arteries ( Right and Left )
• Basilar artery ( Prox, Mid, Distal )
TCDI- Transorbital Window
Segments recorded in a complete exam
• Ophthalmic Artery
• Carotid Siphon
Ophthalmic Artery
TCDI-Transtemporal Window
Low PRF
Optimized PRF
Be aware of your PRF settings when interrogating
the Circle of Willis arterial segments
High PRF
TCDI-Transtemporal Window
Low PRF
Optimized PRF
Be aware of your PRF settings when interrogating
the Circle of Willis arterial segments
High PRF
TCDI-Transtemporal Window
Low PRF
Optimized PRF
Be aware of your PRF settings when interrogating
the Circle of Willis arterial segments
High PRF
TCD Interpretation
Patients Clinical Presentation
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SAH
Head injury
Tumor
AVM
Aneurysm
Extracranial vascular disease
Subclavian steal syndrome
Brain death
TCD and TCDI
Interpretation Criteria
• MCA carries 80% of flow to the cerebral
hemispheres
• MCA mean velocities >ACA>PCA>Basilar
>Vertebral
• Normal mean velocities should be <90 cm/s
• Mean velocities with mild vessel narrowing are
>120c m/s
TCD and TCDI
Interpretation Criteria
• Elevations in Mean Velocities may be due to:
– Vasospasm – associated with trauma, SAH
(subarrachnoid hemorrhage), aneurysm
• Generalized increase in velocities
• Changes over time
– Stenosis – focal increase in velocity with PST
– Collateral flow – associated with change in direction
– Hyperdynamic flow – associated with head injury/AVM
• Increased velocities in all vessels
TCD and TCDI
Interpretation Criteria
• Pulsatility Index
– Measures the peripheral resistance in the vascular bed
– Absolute values alone are not very accurate, but
changes in PI over time is an indicator of the severity
of dilation
– Normal = .9 – 1
MicroMaxx
Patient / Exam Type
TM
• TCD
– High output
power
• Orbital
– Low output
power
MicroMaxx
Doppler Quantification
TM
• Auto Trace results
– Fast and reproducible
– Displays
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TAP ( TCD mean )
Peak Velocity
End Velocity
Pulsatility Index
Resistive Index
Systolic/Diastolic Ratio
Doppler Gate Size
Sample Volume Depth
– Manual Trace also available
MicroMaxx TCD Report Pages
TM
Summary
• MicroMaxxTM offers the clinician a complete
cardiovascular imaging system
• Small, portable system easily taken to patients’
bedside
• TCD and Orbital exam types
• Comprehensive report package
• High-end application on an affordable system