Carotid Duplex/Color Flow Imaging

Question 1

Accelerated flow mistakenly attributed to stenosis instead of what?

Answer 1

• Cardiac output
• Tortuous vessel
• Compensatory flow
• Inappropriate Doppler angle

Question 2

Disease process could be under-estimated if accelerated flow not present or detected such as?

Answer 2

• Jet of accelerated flow missed
• Long, smooth plaque formation
• Stenosis at area of dilatation
• inappropriate Doppler angle

Question 3

Individual frequencies/velocities displayed with time on horizontal axis and various frequency shifts/velocities on vertical axis

Answer 3

Fast Fourier TRansform (FFT) method

Question 4

What displays true frequency/velocity shifts and utilizes the FFT method?

Answer 4

spectral analysis

Question 5

Two piezo-electric crystals, one constantly sending and one constantly receiving reflected waves. No range resolution and fixed sample size?

Answer 5

Continuous wave Doppler

Question 6

Crystals send then receive the reflected ultrasound. Has range resolution, variable sample size, and well-defined spectrum?

Answer 6

pulsed Doppler

Question 7

Spectral window is filled in with what type of Doppler?

Answer 7

CW Doppler

Question 8

Assigns color to display average frequencies and direction of moving blood?

Answer 8

color Doppler

Question 9

With color Doppler, pulse doppler beams evaluate multiple samples sites throughout a specific area. Scan rates are _____ because of multiple transmit/received pulse cycles in each color line of site.

Answer 9

slower

Question 10

Normal ICA Doppler signals?

Answer 10

More high-pitched and continuous than ECA

Rapid upstroke and down stroke with a high diastolic component

Question 11

ECA normal Doppler signals?

Answer 11

Signal more pulsatile, vary similar to peripheral vessels

Rapid upstroke and down stroke with low flow in diastole

Question 12

How can a stenosis be characterized by abnormal Doppler signals?

Answer 12

Higher pitched sound and waveform with higher velocity. Spectral broadening evident and loss of spectral window.

Question 13

Distal to a stenosis has what type of flow patterns?

Answer 13

turbulent, bi-directional, can be dampened and monophasic/continuous

Question 14

Consider disease at carotid siphon when high resistant flow patterns evident in?

Answer 14

ICA

Question 15

DIminished velocities in what vessel bilaterally may indicate poor cardiac output or stroke volume?

Answer 15

CCA

Question 16

Diminished velocities unilaterally suggests prox disease where?

Answer 16

innominate or common carotid artery

Question 17

Criteria that is critical in determining an occlusion?

Answer 17

• CCA may have a ver low or absent diastolic component
• Evidence of collateralization when ECA may exhibit high flow in end diastole
• Absent ICA Doppler signal or pre-occlusive thump

Question 18

Misrepresentation of Doppler signal due to limitations of the equipment being used is called what?

Answer 18

aliasing

wave firm has flat, crew-cut appearance

Question 19

Maximum frequency is 1/2 PRF. Flow information greater than 1/2 PRF cannot be displayed is called what?

Answer 19

Nyquist limit

Question 20

What are methods of increasing the PRF/Nyquist limit?

Answer 20

Decrease the baseline, increase Doppler scale, change frequency, alter angle of insonation, decrease depth, or use continuous wave Doppler

Question 21

Doppler shifts above and below the baseline, displaying a duplicating spectrum or color-flow Doppler. What type of artifact if from strong reflectors or too much gain?

Answer 21

Mirror imaging

Question 22

What occurs when flow moves into a wider portion of the vessel?

Answer 22

helical flow

common in the carotid bulb

Question 23

Characteristics of helical flow?

Answer 23

• Doppler shifts above and below the baseline
• Spectral waveforms are different
• Doppler angle constantly changing
• Flow is not laminar ; spectral broadening present