Ch. 10 Vascular Flashcards
What important vessel participates in anterior circulation
cavernous ICA (carotid siphon)
What is another name for the cavernous ICA
carotid siphon
What instrument is used for non-imaging
TCD (1-2 MHz)
What does TAP-V stand for
mean velocities
All vessels in the intracranial system have ____ resistance and ____ diastolic flow, except which vessel
low, high, Ophthalmic artery
The Ophthalmic artery has what resistance and flow
high resistance, low diastolic flow
What anatomical approaches (acoustical windows) are used to access cerebral vasculature
transtemporal, transorbital, transoccipital, submadibular
What is the 5th acoustical window/anatomical approach that can be used to image intracranial vessels
atlas loop
In transorbital approach, where is ultrasound transmitted
through the thin orbital plane of frontal bone
In transorbital approach, ______ must be reduced to limit direct exposure to the eye
power intensity
In atlas loop approach, what is it used to evaluate
extracranial vertebral artery
In atlas loop approach, where is the transducer placed
below the mastoid process, behind the sternocleidomastoid muscle
The examination technique has five primary criteria used to identify a vessel, what is the equation for flow velocity
MCA>ACA>PCA=BA=VA
Where does the VA confluence occur
approximately 70 mm depth
The VAs join together to form
basilar artery
BA is traced throughout its ______ because it is a
length, long vessel
What are the 3 segments of the cavernous ICA/carotid siphon
parasellar, genu, supraclinoid
ICA branches
ophthalmic artery, posterior communicating artery (PCOA)
In doppler imaging for the OA, where do you aim the transducer
medially
When imaging the OA, what depth is the color box placed and what do you do with the scale
40 to 60 mm, lower
Normal flow in the OA is directed _____ the transducer
toward
Normal flow in the OA is
from the brain toward the orbit of the eye
If collateral from the ECA, the flow in the OA is
from the eye to the brain
OA waveform will have
low velocity with high resistance
in duplex imaging, carotid siphon transducer placement will be
same orientation as OA
In duplex imaging, the color box for the carotid siphon is placed at what depth? What happens to the color scale
60 to 75 mm, increase color scale slightly
In duplex imaging, the flow in the carotid siphon may be
toward, away or both
In duplex imaging for the posterior cerebral artery (PCA) place the color box
around butterfly-shaped midbrain (PCAs encircle it)
In duplex imaging for the PCA, P1 segment flows
towards the transducer
In duplex imaging for the PCA, P2 segment typically flows
away from the transducer
In duplex imaging of the submandibular approach, the retromandibular ICA is obtained in patients that require calculations of
the lindegaard ratio
The lindegaard ration is useful in differentiating _____ volume from _______ vessel diameter with ______ velocities
increased, decreased, high
Technical considerations of anatomical variations in the circle of willis (50%) include
differences in origin, size (caliber) and course of vessel
When diagnosing, the spectral waveform parameters include
velocity (TAP and PSV), pulsatility
Velocity in spectral waveform parameters is also referred to as
mean velocity or TAP and PSV
Pulsatility in spectral waveform parameters is also expressed as
gosling pulsatility index
In collateral flow, the ECA to ICA through reversed OA have
retrograde flow in OA, decreased pulsatility, increased velocity in OA, reversal of flow in the OA with compression of the branches of the ECA
TCD is useful for detection of >50%
intracranial stenoses and occlusions
Conditions that produce stenosis include
atherosclerosis, dissection, FMD, moyamoya disease
Vasospasm interpretation is complicated by
hematocrit, arterial CO2
What 3 things can all affect intracranial velocities
hematocrit, CO2 levels and age
TCD an be used to monitor for emboli during procedures such as
CEA, CAS, cardiopulmonary bypass surgery, neurological procedures
________ signals have a unique _______ signature
microembolic, doppler
What is the microembolic signal that has a unique doppler signature also called
HITS
What is the percentage for anatomical variations in circle of willis
50%
What are the two things in mean velocity
TAP and PSV
Application for intracranial exam, collateral flow, ECA to ICA through
reversed ophthalmic artery
