CH 20: carotid duplex scanning and color flow imaging

Fill in the blanks regarding the capabilities of a carotid exam.

1. Localize presence of _________ disease in carotid arteries

2. Differentiate _________ from ________

3. Document progression of ________

4. Provide information about _________ characteristics  

5. Evaluate a ________ mass

1. Arterial

2. Occlusion, Stenosis

3. Disease

4. Surface

5. Pulsatile

If a doctor palpates a pulsatile mass in the neck, what is the most likely diagnosis?

Tortuous vessel

Label the structures on this image. 

1. ICA

2. ECA

3. CCA

Poor visualization of the common carotid artery can be due to what 6 factors?

• Presence of dressings, skin staples, or sutures 

• Size or contour of patient’s neck

• Patient movement

• Depth or course of a vessel

• Rapid respiratory pattern

• Acoustic shadowing from calcification

What kind of limitation to a carotid exam is seen here?

Course of a vessel (tortuous)

List the 2 ways a sonographer can overestimate disease in carotid.

• Artifact is mistaken for plaque

• Accelerated flow is mistakenly attributed to a stenosis

A sonographer can accidentally mistaken artifact in the carotid for what pathology?

Plaque

A sonographer can accidentally mistaken accelerated flow in the carotid for what pathology?

Stenosis

List the 4 reasons why accelerated flow is seen in the carotid if it is not a stenosis.

• Increased cardiac output

• Vessel tortuosity

• Compensatory flow

• Inappropriate doppler angle

What is compensatory flow in the carotid?

When one side is diseased, the other side making up for it

Fill in the blanks of the 5 ways a sonographer can underestimate disease in the carotid.

1. Failure to distinguish ______________ of soft plaque 

2. ________ flow is not present or detected

3. Long, smooth plaque formation may not have _________, __________ flow patterns

4. A ______ bifurcation limits through evaluation of the ICA 

5. Inappropriate doppler _______ is used

1. Low level echoes

2. Accelerated

3. Accelerated, turbulent

4. High

5. Angle

Evaluate closely for the sonographic finding seen in the carotid here.

Low-level echoes of soft plaque

Name the physical principle:

“Combines physiological information based on spectral analysis with the anatomic information of real-time, high-resolution, gray-scale imaging.”

Duplex ultrasound

Name the physical principle:

“Evaluates the doppler flow information for its direction, toward or away from the transducer, and its frequency content (which determines the hue or shade of the assigned color.”

Color flow imaging

Duplex ultrasound will combine physiologic information based on spectral analysis with the anatomic information of what 3 factors?

• Real-time

• High-resolution

• Gray-scale imaging 

Color flow imaging evaluates the doppler flow for what 2 factors?

• Direction toward or away from the transducer

• Frequency content

The frequency content seen in a color image will determine which 2 factors of the assigned color?

• Hue

• Shade

Is this image showing flow towards or away from the transducer?

Towards

Name the physical principle:

“Uses 2 piezoelectric crystals, one constantly sending ultrasound, one constantly receiving reflected waves.”

Continuous wave doppler

For continuous wave doppler, what do the 2 piezoelectric crystals do?

• One constantly sends ultrasound waves

• One constantly reflects ultrasound waves

Which one has no range resolution?

• Continuous wave doppler

• Pulse wave doppler

Continuous wave doppler

Which one has range resolution?

• Continuous wave doppler

• Pulse wave doppler

Pulse wave doppler

Which one has a fixed sample size?

• Continuous wave doppler

• Pulse wave doppler

Continuous wave doppler

Which one cannot place the sample volume at a specific depth?

• Continuous wave doppler

• Pulse wave doppler

Continuous wave doppler

Which one has a limited use in carotid imaging?

• Continuous wave doppler

• Pulse wave doppler

Continuous wave doppler

Which form of doppler imaging is seen here?

Continuous wave

Name the physical principles:

“The multiple crystals in the transducer are transmitted in a quick burst, producing ultrasound waves.”

Pulsed-wave doppler

Which one has a transducer with multiple crystals?

• Continuous wave doppler

• Pulse wave doppler

Pulse wave doppler

Which one has a transducer with 2 crystals?

• Continuous wave doppler

• Pulse wave doppler

Continuous wave doppler

The burst of the multiple crystals in a pulse wave transducer is followed by what period?

Listening period

Describe what the ‘listening’ period of a pulse wave doppler transducer is.

When the crystals detect the reflected signals

What is range resolution used for?

Knowing how deep we are

What is the primary tool used for the evaluation of blood flow? 

Pulse wave doppler 

Pulse wave doppler provides accurate information regarding what 2 things?

• Blood flow characterization

• Image of the anatomy

1. What kind of imaging is seen here?

2. It is the primary tool for the evaluation of what?

1. Pulse wave doppler

2. Blood flow

A reproducible and consistent velocity measurement requires what angle degree? 

45 - 60

What angle of insonation provides the greatest doppler shift?

Zero

The criteria used in interpreting the significance of velocity measurements were established using a __ degree angle of insonation.

60

Why is an insonation angle of zero not used? 

Due to the vessels being parallel to the skin’s surface, so it’s not possible

A 60-degree angle is not always attainable due to what 2 factors?

• Anatomic location of the arteries

• Normal curvature of the arteries

In cases where an exact angle of 60 degrees is not attainable, the angle will more often be what 2 things?

• Less than 60 degrees

• Between 45-60 degrees

Which angle is more likely to have measurement errors? 

• Greater than 60 degrees

• Less than 60 degrees 

Greater than 60 degrees

Spectral analysis is the display of the…

Waveforms

Name the physical principle:

“Displays the frequencies of blood flow during systole and diastole.”

Spectral analysis

Spectral analysis displays the (1)___________ of blood flow during (2)________ and _________. 

1. Frequencies

2. Systole, diastole

Which physical principle uses the FFT (fast Fourier transform) method?

Spectral analysis

1. What is the name of the technology that analyzes and displays the individual frequencies of the returned signals?

2. This technology is associated with what imaging feature?

1. Fast Fourier transform

2. Spectral analysis

The Fast Fourier transform analyzes and displays the individual (1)__________ of the (2)__________ signal.

1. Frequencies

2. Returned 

The Fast Fourier Transform creates a velocity profile consisting of what 3 factors?

• Time on the horizontal axis

• Velocity on the vertical axis

• Intensity of the signals as brightness 

With continuous wave doppler, what doppler finding is expected/normal even with laminar flow?

Spectral broadening

Pulsed doppler will produce what kind of spectral waveform when a limited number of frequencies or velocities are evident in laminar flow? 

Narrow, well-defined

Which of the 2 will consider spectral broadening a normal finding?

• Continuous wave doppler

• Pulse wave doppler

Continuous wave doppler

Which of the 2 will associate spectral broadening with turbulent flow?

• Continuous wave doppler

• Pulse wave doppler

Pulse wave doppler

Spectral broadening seen in a continuous wave doppler is considered…

Normal

Spectral broadening seen in a pulse wave doppler is associated with…

Turbulent flow

On a spectral waveform, what is represented on the horizontal axis? 

Time

On a spectral waveform, what is represented on the vertical axis? 

Velocity (Frequency shift)

What is another term for frequency shift?

Velocity

On a spectral waveform, time is represented on which axis?

Horizontal

On a spectral waveform, velocity (frequency shift) is represented on which axis?

Vertical

What represents the question mark on this image?

Velocity

What represents the question mark on this image?

Time

What represents the question mark on this image?

Spectral window

What represents the question mark on this image?

Spectral intensity

What represents the question mark on this image?

Spectral width

The intensity/brightness is also referred as what?

The grayscale velocity plot

The intensity/brightness of the spectral line represents what?

The number of RBCs that are reflecting the ultrasound beam at each velocity

Which aspect of the spectral line represents the number of RBCs that are reflecting the ultrasound beam at each velocity?

Intensity/brightness

The width of the spectral line represents what?

The range of velocities within a vessel

Which aspect of the spectral line represents the range of velocities within a vessel?

Width

The width of the spectral line can vary during normal cardiac cycles:

1. ___________ during systole

2. ___________ in diastole

1. Narrowing

2. Widening

Where is the spectral window seen on a spectral line?

Between the spectral line and baseline

Which aspect of the spectral line represents the clear black zone between the spectral line and the baseline?

Spectral window

Which aspect of the spectral line represents the widening of the spectral line and filling of the spectral window?

Spectral broadening

Describe how spectral broadening appears on a spectral waveform? (2)

• Widening of the spectral line

• Filling of the spectral window

Spectral broadening can be found in the presence of what 3 things?

• High flow velocity

• Branching of a vessel

• Small diameter vessels

Which of these 2 waveform images represents a waveform seen on a continuous wave doppler? 

Bottom

What is the name of this circled finding on the spectral waveform?

Spectral broadening

What 2 factors should the sonographer look for when evaluating the walls of a vessel in grayscale?

• Absence of wall irregularities

• Solid color

Name the pathology:

“Hypoechoic and homogenous low-level echoes of similar appearance.” 

Fattty streaks

List the 3 sonographic findings of fatty streak plaque.

• Hypoechoic

• Homogenous

• Low level echoes

Fatty streak plaque can be found in what age group?

Any

Name the pathology:

“Low to medium level echoes”

Fibrous (soft) plaque

Fibrous plaque is also referred to as…

Soft plaque

List a sonographic finding of fibrous/soft plaque. 

Low to medium level echoes

List a sonographic finding of complex plaque. 

Heterogenous echoes

Name the pathology:

“Heterogenous echoes indicating soft and dense areas”

Complex plaque

The heterogenous echoes seen inside complex plaque can indicate what kind of areas? (2)

• Soft

• Dense

List the 2 sonographic findings of calcifications seen in a vessel. 

• Very bright reflective echoes

• Acoustic shadow

Name the pathology:

“Very bright reflective echoes with acoustic shadowing that can prevent a thorough evaluation of the vessel.” 

Calcification 

Acoustic shadowing from a calcified vessel can prevent the ____________ evaluation of a vessel.

Thorough

How does the echogenicity of a fresh thrombus compare to the echogenicity of flowing blood? 

It is the same

Careful evaluation of a fresh thrombus is…

Necessary

List the 4 terms used to describe the surface characteristics of plaque.

• Smooth

• Slightly irregular

• Grossly irregular

• Crater-like

When evaluating a stenosis, it should be visible in 2…

Planes

Depending on the type of occlusive process, the material filled in the vessel can have which 2 sonographic characteristics?

• Highly echogenic

• Anechoic

Doppler findings are essential for an occlusion but __________ characteristics are helpful.

Grayscale

What kind of plaque is seen here?

Fibrous/Soft plaque

What kind of plaque is seen here?

Complex plaque

What kind of arterial pathology is seen here?

Calcification