Week 1: Intro and Basic Terminology Flashcards
_______ is an ultrasound-based diagnostic imaging technique to evaluate structural details of the carotid arteries. It is used to diagnose carotid artery stenosis and can assess atherosclerotic plaque morphology and characteristics.
carotid duplex exam
Indication for the carotid duplex exam (6)
- syncope
- stroke
- AMS (altered mental state) i.e. cognitive disorders, attention disorders, decreased level of consciousness
- TIA
- Bruit
- follow up for known stenosis
Rt CCA (right common carotid artery) further bifurcate into internal and external carotid arteries at the ________
carotid bulb
Carotid bulb supplies blood to _____ and ______
brain and face
Vertebral arteries arise from ________ traverse cephalad through the _______\_ of the cervical vertebrae: ______ and train the brain through the posterior fossa
subclavian artery
transverse formina
C1 - C6
Confluence of all these vessels joined to make the _______ (a circular and a somatic arterial network at the base of the brain) at the base of the brain
Circle of Willis
Three walls (layers) of artery/vein ?
- Tunica interna
- Tunica media
- Tunica adventitia
*note: The middle muscular layer of the arteries are thicker than the veins
In which layer does the plaque build up?
tunica media
Blood flow through the common carotid artery is usually____, however, it’s not true of the ____ and in case of tortuous vessels (see below)
*type of flow
laminar flow
bulb
Carotid artery has a ________and ________ (see below)
*explain flow
sharp up stroke and a decent amount of diastolic flow
What waveform?
The internal carotid artery has a broad upstroke and a considerable amount of diastolic flow
Which waveform ?
The external carotid artery has a very sharp upstroke and can have little to no diastolic flow or even reversal flow (see below)
Spectral Doppler angle should be _______ in order to avoid overestimating the velocities
45-60 degrees
*angles greater than 60 degrees lead to significant erros in velocity
ICA/CCA ratio is important for estimating _______
stenosis
ICA/CCA ratio equation
ICA PSV / CCA PSV
The peak systolic velocity of the ICA and the peak systolic velocity of the CCA and divide them
What is normal range of ICA/CCA ratio ?
*ICA/CCA ratio < 2.0 wnl is considered within the normal range. It is an estimate of at least less than 50% stenosis which can be described as no hemodynamically significant stenosis.
Appearance of atheromatous plaques
homogeneous echolucent
Appearance of atheromatous plaques
homogeneous echogenic
Appearance of atheromatous plaques
heterogeneous plaque
Appearance of atheromatous plaques
cauliflower calcification
- Appearance: differentiate whether the surface is smooth or irregular
- Texture: homogenous= _______ or heterogeneous = ________
- Keep an eye out CVC (central venous catheter) - any intra plaque hemorrhage or alteration
fatty plaque
contain calcium
The characteristics of waveform in stenotic vessel
- Increased velocity
- Waveform change - turbulence, spectral broadening, tardis parvis (in the distal site of stenosis)
A normal exam is considered:
velocity?
presence of plaque?
CCA ratio?
- a piece of solid velocity of less than 125 cm/s
- No plaque
- CCA ratio less than 2.0
A 50-69% stenosis is considered:
velocity?
presence of plaque?
CCA ratio?
- ICA peak systolic velocity of 125 to 230 cm/s
- A plaque % estimate of 50% or more
- CCA ratio 2-4
A greater than 70% stenosis is considered:
velocity?
presence of plaque?
CCA ratio?
- Velocity is higher than 237 cm/s
- Plaque estimate greater than 50%
- ICAC CCA ratio greater than 4
*Once you start reaching levels of near occlusion or total occlusion, these parameters cannot be used to find out the degree of stenosis because there may be no flow or the trigger flow will have no Doppler spectrum
Much less common pathologies:
carotid dissection - a tear in the layers of the arterial wall which allows blood to pool in between them and causes a flap and increase turbulence of flow and creates blood clots which can then embolize across stroke
Much less common pathologies:
Carotid body tumor - tumors that form at the bifurcation of the carotid artery also called: paragangliomas. They represent about 65% of head and neck paragangliomas
Much less common pathologies:
Fibromuscular dysplasia
- disease process that affects the medium and large arteries of young to middle aged women and an imaging usually has the string of pearls or string of beads appearance which describes as a series of lumen stenosis and aneurysmal out pouches
Much less common pathologies:
Takayasu’s Arteritis - another rare vascular inflammation of the arterie, usually the large vessels from branching off of aorta
medical jargon and buzzwords
appreciate
used in medicine to mean “discern - perceive, recognize” or “distinguish”
ex: in the more posterior approach, we can better appreciate the crater-like formation at the origin of the internal carotid.
medical jargon and buzzwords
proximal limit/distal limit
farthest possible point toward or away from the heart or point of origin
medical jargon and buzzwords
terms used interchangeably: plaque
*plaque is used in sigular
atheroma: degeneration of the walls of the arteries caused by accumulated fatty deposits and scar tissue, and leading to restriction of the circulation and a risk of thrombosis
atheromata:
areas of atheroma
areas of calcification
atheromatous development
medical jargon and buzzwords
thickened walls along the artery, looking a bit like very minimal atheroma called:
intimal thickening
medical jargon and buzzwords
true lumen vs residual lumen
true lumen: the actual wall of the vessel
residual lumen: the remaining (of narrowed vessel from plaque) opening through which blood continue to flow
medical jargon and buzzwords
homogeneous vs heterogeneous
all of one consistency vs having different consistencies or materials
pea soup vs beef stew
medical jargon and buzzwords
The shape that is most suggestive of ulceration of plaque; scooped-out in appearance, especially if there are shelf-like projections over the arater
crater, crater-like in aeparance
medical jargon and buzzwords
caudal
toward the feet
medical jargon and buzzwords
Plaque
Atherosclerotic material that builds up on the walls of arteries
Embolus
Object traveling through the circulation that may lodge in a
vessel and cause occlusion.
- Several types: thrombus, air, tumor cells, clumps of fat, etc.
- Arterial vs Venous
identify 1-4
- ECA
- ICA
- bulb
- CCA
What is Hemodynamics?
Study of blood flow characteristics
Blood flow results due to a continual difference in pressure as blood travels through the circulatory system
- Blood always flows from _____ pressure to _____ pressure
- Blood will always take the path of ______resistance
higher, lower
least
Laminar flow
Orderly, non-turbulent flow
- Smooth parallel flow in layers
- Similar velocities across the vessel diameter
Parabolic flow
Center stream is faster, bullet shaped
Plug flow
All fluid traveling at a very similar speed and direction
- Common in larger vessels
- Creates a flattened forward patters
Turbulent flow
-Opposite of laminar flow
-Commonly associated with diseased vessels, but there are other causes that are not
disease related
• Bifurcations & branching
• Curved (tortuous) vessels
• Changes in the natural vessel diameters
Doppler Effect
Shift in frequency caused by motion between the source and the observer
-Occurs twice in vascular ultrasound
1. Transducer is a stationary source while the blood cells are moving receivers of the
ultrasound waves
2. The ultrasound is backscattered from the blood cells, which now act as a moving
source, with the transducer acting as a stationary observer
Flow
The volume of blood passing a point at a given time
Resistance
Force that opposes the flow of fluid
-Factors that affect resistance: increase in viscosity, increase in tube length, decrease in radius (all increase
resistance)
**Flow and resistance are opposites!
-High resistance = low flow
Doppler Equation
f (d) = 2fv cos theta / c
f: transmitted frequency
v: velocity of the blood
c: propagation speed
Spectral Doppler
Multiphasic vs Monophasic
*normal peripheral arterial flow is multiphasic
triphasic
Multiphasic vs Monophasic
biphasic
Multiphasic vs Monophasic
monophasic
Wall Filter
- Low (slow) flow requires low wall filter
- High dynamic flow requires higher wall filter
Characterizing Atheromatous Lesions
Calcific, dense appearance in echo?
-Bright echoes in the lumen
Characterizing Atheromatous Lesions
Soft, fibrous appearance in echo?
darker echoes
Characterizing Atheromatous Lesions
Intimal Thickening appearance in echo?
- Thickened walls around the artery
Characterizing Venous Images
Patent meaning ?
compressible meaning ?
patent: Open, unobstructed, affording free passage. Characteristics of normal veins
compressible: Compress with probe pressure
Characterizing Venous Images
Chronic vs. Acute thrombosis
echo appearance for each?
- Chronic: brightly echodense, heterogeneous, striated, collaterals present
- Acute: softly echogenic, homogeneous, lightly speckled echoes, no collaterals
Characterizing Venous Images
Recanalized meaning?
Having formed a channel of flow through a thrombus
-Suggestive of older/chronic clot
Characterizing Venous Images
Nonocclusive meaning?
-Obstructed but not totally blocked
patent in medical meaning
Patent (adjective): Open, unobstructed, affording free passage. Thus, for example, the bowel may be patent (as opposed to obstructed)
Quiz Question
- Antegrade flow is defined as which of the following?
a. Flow moving in the incorrect direction
b. Flow directed toward the head
c. Flow moving in the correct direction
d. Flow directed toward the front of the body
c. Flow moving in the correct direction
Quiz Question
- True or False: Hemodynamics is the study of blood flow characteristics.
T
Quiz Question
- Describe the difference between laminar and turbulent flow
My Ans:
laminar - blood flow in parallel in a same direction. The fastest in the center and gets slower as it’s closer to the wall. parabolic shape profile
turbulent - blood flow in different directions with different velocities. It can be seen at the bulb, bifurcation, and stenotic vessels.
Quiz Question
- Which best describes the spectral waveform demonstrated below?
a. Triphasic
b. Monophasic
c. Hyperemic
d. Biphasic
a. Triphasic
Quiz Question
_*_flag question (partial credit)
- List 2 ways to better optimize this spectral waveform:
My Ans:
increase color scale to eliminate aliasing
move baseline down to show the full spectral Doppler waveform
Comment:
Both good suggestions, but only one is for optimizing the spectral waveform as requested by the question!
Quiz Question
- Describe 2 key differences between the ultrasound appearance of acute vs. chronic thrombosis.
My Ans:
acute - echolucent homogeneous appearance
chronic - calcific, echogenic appearance
Comment:
Acute is typically hypoechoic, dilated, soft, spongy, regular, may have flow around if loosely attached. Chronic is typically hyperechoic, may be atrophied, hard, irregular, likely to have flow through it.
