doppler 3

Doppler instruments respond to moving reflectors (RBCs) by detecting the

Doppler shift

Doppler shift is converted to

audible sound

Visual display

color Doppler –

•power Doppler -

•spectral analysis –

 

l– color display

– color display

– waveform display

 

what are 4 types of Doppler Instruments

Color Doppler

•Power Doppler

•Continuous Wave (CW) spectral analysis

•Pulsed wave (PW) spectral analysis

The color information is then superimposed on a

 

2D image

one color represents ____the transducer, while another color _____

 

flow toward

represents flow away

black and white mean

real time structures

color:

flow or reflector motion information

color Doppler is a _____ technique and is bound by the _______

pulsed ultrasound

physics of pulsed waves

Color Doppler provides range resolution at the expense of

aliasing

the change of color can also represent  

differences in flow velocities

blood flow through a vessel is not uniform

TRUE OR FLASE

True it’s not uniform

•color closest to the neutral color represents

•color farthest away represents

low velocity flow

peak velocity flow

If vessel demonstrate neutral color means

No blood flow or motion in the sample region

Flow exists but is perpendicular

To beam

-heeltoe vessel to get away from

90 degrees

What are the variety of color maps /color characteristics include ? What are they?

Hue - the color you see, red blue, greeen

Luminance - the brightness of the color

Saturation-the amount of color mix with white.

Less white =

greater saturation

Red vs pink

A varies color map can be use and display ?

Display blood flow at different speeds - variations of low velocities

isturbed and/or turbulent flow

 

Color used ij variance maps are

Yellow, cyan, green

What are some of color Doppler controls

gain

•window location

•width & depth

•steer/angle

•color invert

•wall filter-increase wall filter you’re moving low level velocities

•scale

•baselin

•priority

•smoothing

•ensemble length

Describes wall filter

Remove low level velocities

Increase wall filter you’re removing low level velocities

When you get a little bit of flashiness outside the vessel it’s. Reaction to pushing which is call flutter

Color Doppler is a function of and subject to ?

PW Doppler and aliasing artifact

Doppler information is collected in many locations (____) in a specific region (_____

Gates and color box

•the number of pulses or gates =

Packet size

the more pulses in packet,

 

the more accurate the velocity measurement

the larger the packet size, however, the

Lower the frame rate decrease temporal resolution

Since velocities are not constant

an average (mean) velocity is measured per gate

Autocorrelation is the rapid technique used for

obtaining the mean Doppler shift information

FFT is too ____ for color Doppler but more ____

Slow, accurate

Advantage included

Locating vessels

Documenting presence of flow

Characteristics of flow patterns

How many colors are commonly use ?

2 or 4

Color Doppler is a function of

PW Doppler

Doppler information is collected in many locations ____ in a specific region ____

gates, color box

What is the advantage in usefulness of color dopper

locating vessels

•documenting presence of flow

•characteristics of flow patterns

on spectral analysis flow may fall to baseline indicating no flow or may fall below baseline indicating flow reversal