Term
| What is color flow imaging? |
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Definition
| - Color flow imaging is producing a grey-scale image with super-imposed colors to represent both color flow direction and velocity. |
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Term
| What are the different dimensions color flow can be demonstrated in? |
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Definition
- Length
- Width
- Velocity (color) |
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Term
| What do the length and width dimensions of color flow imaging represent? |
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Definition
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Term
Color Mode
- Obtains _1____ measurements from multiple __2__ within a box. |
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Definition
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Term
| What determines a gate in a color box? |
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Definition
| - The gate is determined by the vertical size of the box. |
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Term
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Definition
- The entire area is scanned line by line to create gray scale image.
- The area in the color box is rescanned to obtain velocity information. A pulse or group of pulses sent out for each line. |
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Term
| Explain color box and temporal resolution |
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Definition
- The bigger the box, the more lines there is.
- The number of lines is also regulated by the line density (Frame rate function)
- The bigger the border of the bottom of the box to the top, the longer is takes for each pulse to return and send the next pulse(s). |
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Term
| Explain flow direction on a color map. |
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Definition
- Flow TOWARDS the transducer s always displayed ABOVE the black horizontal line.
- Flow AWAY from the transducer is always displayed BELOW the black horizontal line. |
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Term
| Explain flow speed with a color map. |
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Definition
- Colors CLOSER to the black line indicate SLOWER velocities.
- Colors AWAY from the black line indicate FASTER velocities. |
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Term
| Explain the different types of color maps. |
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Definition
- BART: blue away, red towards
- RABT: red away, blue towards |
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Term
| Explain the direction of flow with the vectors. |
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Definition
- The vector arrow off the line of insonation points TOWARDS the probe, if blood flow is TOWARDS the probe.
- The vector arrow off the line of insonation points DOWN or AWAY from the transducer if the flow is moving AWAY from the transducer. |
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Term
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Definition
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Term
| What could cause a color change? |
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Definition
- Aliasing
- Turbulence
- Reversal component of a high resistant vessel |
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Term
T or F
Color map has a baseline that can be changed. |
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Definition
True;
The baseline (black horizontal line) can be adjusted up and down.
For example the baseline could be moved down and then the scale for flow towards the transducer can show more of a velocity range than flow away from the transducer.
(Refer to picture on slide |
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Term
| How does the system accurately measure a velocity of a RBC? |
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Definition
| The system sends out several pulses and averages the doppler shift it receives. |
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Term
| What is a packet size (data number)? |
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Definition
| - The packet size (data number) is the number of pulses used for averaging to find the velocity. |
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Term
| The ______ pulses in a packet, the ____ accurate the velocity measurement. |
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Definition
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Term
| How do the number of pulses in a packet affect temporal resolution? |
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Definition
| - The more pulses in a packet, the more time is needed. This decreases frame rate which decreases temporal resolution. |
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Term
| What are the different types of color maps? |
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Definition
- Velocity
- Variance
- Power |
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Term
| Explain Velocity mode in a color map |
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Definition
| - All of the velocities for a particular location are averaged and only the mean velocity is displayed in color. |
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Term
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Definition
- The velocities in an area are measured and the mean velocity is the color that is displayed.
- The VARIATION in velocities are then measured in well, with lots of variation, it'll indicate turbulent flow and the color is usually a green or yellow pixel.
- The color map has variations in color from top to bottom and left to right. |
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Term
| What are the possible names for Power doppler? |
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Definition
- Ultrasound Angiography
- Amplitude Doppler
- Color Amplitude Imaging (CAI) |
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Term
| What does brightness on the power doppler color map represent? |
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Definition
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Term
| What does darkness on the power doppler color map represent? |
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Definition
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Term
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Definition
- Instead of analyzing v (doppler shift) vs. time it graphs amplitude vs time. The integral of power spectrum is estimated and color coded.
- The power doppler image only indicated that blood flow is PRESENT, not any information about velocity.
- Power doppler is very sensitive, it can pick up even low flow velocities at poor angles. |
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Term
| What methods give us velocity detection? |
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Definition
- Doppler
- Cross-correlation |
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Term
| Doppler and cross-correlation are both dependent on what? |
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Definition
| - DOPPLER AND CROSS-CORRELATION ARE BOTH ANGLE DEPENDENT ** |
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Term
| With color doppler, what is calculated? |
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Definition
| - Similar to spectral analysis, DOPPLER SHIFT is calculated. |
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Term
| Why is Autocorrelation used instead FFT analyzer with color doppler? |
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Definition
- With color doppler, there is a LARGE COLOR BOX, with MULTIPLE LINES, sending back large amounts of velocity information.
- Because of all this information, the FFT analyzer is not fast enough to keep up, so then the FFT analyzer is NOT used with color doppler. |
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Term
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Definition
- A minimum of 3 pulses are sent out to obtain information for each gate location.
- Comparing the 1st and 2nd pulse yields phase difference (flow direction).
- Comparing the 2nd and 3rd pulses yields doppler shift (velocity) using complex set of algorithms.
- A maximum of 10 pulses can be sent out for greater accuracy (no more because more pulses means worse temporal resolution.
- The mean velocity is displayed in color (velocity mode)
- Also deviations from the mean can be obtained and represented in color as well (variant mode). |
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Term
| Explain Cross-correlation |
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Definition
- Instead of Doppler equation, cross-correlation uses RANGE EQUATION to calculate the blood flow velocity.
- To obtain a velocity measurement a minimum of 2 pulses are needed.
- Most commonly occurring velocity (modal velocity) is displayed in color (velocity mode)
- Deviations from the modal velocity can also be obtained and displayed in color (variant mode) |
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Term
| What is the range equation? |
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Definition
V= ^RTTTxPRF / 13 sec/cm x Cos@
^ = delta (change in) |
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Term
23, 27, 27, 29, 30
Mean?
Modal? |
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Definition
Mean = 23+27+27+29+30 / 5 = 27.2
Modal (most commonly occurring) = 27 |
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Term
Color
Area Evaluated?
Accuracy?
Technique?
3D info? |
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Definition
- Large color box
- Mean or Modal velocities
- Doppler or Cross-Correlation
- LxWxv |
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Term
Spectral
Area Evaluated?
Accuracy?
Technique?
3D info? |
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Definition
- within a gate alone one line
- Very accurate; spectrum of velocities can evaluate PSV, EDV, etc.
- Doppler
- t x v x A |
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