URR 5 Flashcards by Billie Harney

Baseline can be used to eliminate:

aliasing

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Increasing the ___ allows the display of higher velocities without aliasing

scale

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Velocity scale is also known as:

pulse repetition frequency

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varied color assignments to Doppler shifts

color map

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degree of variability of mean velocity at different depths in the sample

variance

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Typically displayed as a GREEN scale superimposed on the red/blue display

variance

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used to highlight flow turbulence

variance

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determines if a pixel is displayed as shade of black and white or as a color

color priority/threshold

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____ threshold settings display less color (lower color priority)

Lower

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____ threshold settings display more color (higher color priority)

higher

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Color priority/ threshold is necessary to:

minimize color flash/clutter and improper placement of color on vessel walls

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color sensitivity

color persistence

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used to highlight low velocity flow

color persistence

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determines how much of the previous image data is carried over into the current image frame

color persistence

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____ persistence levels allow prolonged display of color on the image and are preferred for slow moving flow

higher

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Increasing persistence makes the live image appear ____ and with improved _____

smooth
color display

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Increased ____ and ____ levels can aid in the evaluation of heavily calcified arteries

persistence
sensitivity

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_____ persistence levels are preferred for evaluation of blood flow through a moving structure (cardiac applications)

lower

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Decrease _____ for improved flow visualization

sample size

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refers to size of color Doppler FOV

color sample size

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____ sample sizes produce better color display

smaller

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Increase ____ from improved visualization

packet size

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refers to the number of lines of information in each sample taken

color packet

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The ___ lines in the sample, the better the display

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____ packet size = better color display

larger

There will be NO color displayed with flow ___ degrees to the ultrasound beam

Flow that is moving in a direction that is ____ to the ultrasound beam will not be detected

perpendicular

Flow best detected moving toward and away from the probe or ____ to the beam

parallel

Increased _____ settings will display more color on the image.

color priority/threshold

Increased color _____ will display a smoother image with reduced image noise, helpful for slow moving flow

persistence

Increased _____ settings will eliminate artifactual color display

wall filter

2D imaging relies on a _____ of the US beam to the structure (reflection).

perpendicular incidence

Color and PW Doppler assess blood flow moving ____ to the US beam

parallel

Demonstrates presence of absence of blood flow

power Doppler

No flow direction displayed

power Doppler

More sensitive to low flow velocities than color Doppler

Power Doppler

used to assess organ perfusion

power Doppler

Preferred for evaluation of vessels with flow moving perpendicular to the US beam

power Doppler

____ sample size for improved flow visualization for power Doppler

Decrease

Unrelated to incident beam angle to flow

power Doppler

demonstrates flow direction

spectral Doppler

Spectral Doppler allows measurement of ____ and _____ flow velocities

peak systolic end diastolic

uses a single piezoelectric element to transmit and receive the signal

pulsed wave doppler

Pulsed wave doppler is limited by:

vessel depth and flow velocities

uses two piezoelectric elements to transmit and receive the signal, not limited by depth or velocity

continuous wave Doppler

Continuous wave doppler is limited by:

nonability to determine flow velocity at a specific location

Benign mass formation usually demonstrates _____ resistance, ____ velocity flow

moderate low

Malignant mass formation usually demonstrates ____ velocity, ____ resistance flow

increased low

_____ usually causes decreased resistance to flow in the area affected

infection

Always use <___ angle of PW cursor with all arterial exams

60 degree

____ sample sizes give more accurate waveforms

smaller

The cursor must be ____ to flow to obtain the most accurate velocity measurements

parallel

The brightness of the reflection on the Doppler tracing represents:

the number of red blood cells moving at each velocity displayed

Doppler gain is ____ related to signal strength.

directly

adjusts the displayed amplitude of the reflected sound waves from the flowing blood

Doppler Gain

makes the whole waveform brighter or dimmer

Doppler Gain

Overgaining on a Doppler exam will cause:

false increase is the peak velocty of the flow

any exam that requires measurement of peak flow velocities requires:

angle correction

The optimum angle between the cursor and the blood flow is ___ degrees or ___ to the flow.

0 parallel

The standard setting for most vascular evaluations is a ___ degree cursor angle.

Changing the cursor angle changes the velocity calculated from the _____ calculated

frequency shift

Overestimating the angle between the cursor and the blood flow will result in:

overestimated velocities

Underestimating the angle between the cursor and the blood flow will result in:

underestimated velocities

_____ is required for any vessel where velocity calculations are necessary

angle correction

adjusts the amount of flow evaluated in a specific location

sample volume size

____ samples sizes produce more accurate Doppler information with ____ evaluation of laminar flow and appearance of the spectral window

smaller improved

Average size of sample volume is ___-___ mm for arterial evaluations

1 1,5

____ sample sizes are helpful for evaluating venous flow and performing volume flow calculations for dialysis access grafts

larger

used to evaluate flow in specific locations

sample volume depth

Necessary for evaluating arterial stenosis

sample volume depth

____ vessels require lower frequency transducers to obtain samples at increased depths

Deeper

aka high pass filter

wall filter

eliminates low frequency Doppler shifts and high amplitude signals from display

wall filter

____, ____, and ____ all involve the incorrect display of lower level Doppler shifts

beam width clutter cross talk

_____ the wall filter can reduce the appearance of the "weaker" Doppler shifts on the image

Increasing

If the filter setting is too ____ it can remove necessary information from the Doppler tracing

high

___ wall filter settings used for venous evaluations compared to arterial evaluations

Lower

If the filter settings are too ____, artifactual information from motion/respiration can degrade the image.

low

used to demonstrate positive and negative shifts appropriately without aliasing

baseline

______ PRF settings used for venous evaluation compared to arterial evaluations

Lower

____ the scale allows the display of higher velocities without aliasing

Increasing

Standard setting for sweep speed is:

50 mm/s

Speed of the spectral Doppler display

sweep speeed

Faster sweep speed (100 mm/s) is recommended for precise measurements of _____, _____, and _____ in general.

acceleration time resistive index waveform tracing

Slower sweep speeds (25 mm/s) can be useful for evaluating _____ and demonstrating _____

venous reflux time cardiac arrythmias

#1 reason for missing a stenosis

improper sample location

Always sample the ____ of the vessel EXCEPT when atheroma/stenosis is present

center

Take multiple samples in the area of the stenosis in case an _____ is present

eccentric jet

Always use <___ degree angle on cursor with any exam where velocity measurements are needed

Adjust ____, ____, ____ to properly demonstrate waveforms

scale baseline gain

____ sample sizes give more accurate waveforms at specific depths

smaller

Cursor must be as _____ to flow as possible

parallel

highest velocity in artery during cardiac systole

peak systolic velocity (PSV)

peak flow velocity in the artery at the end of cardiac diastole

(Peak) end diastolic velocity (EDV)

PSV is used to assess for the presence of:

stenosis

EDV can be used to assess for presence of ____ and _____

stenosis vascular bed resistance

comparison of peak systolic and end diastolic flow velocities and represents the difference between them

resistive index

The greater the difference in PSV and EDV, the ____ the RI

higher

Transducer frequency is inversely proportional to: a. depth of penetration b. axial resolution c. lateral resolution d. second harmonic frequency

measured at the highest velocity displayed on the tracing regardless of its occurrence during cardiac cycle

venous flow velocity