# Krem Ch5 Flashcards

1
Q

Autocorrelation

A

A rapid technique, used in most color Doppler instruments, to obtain mean Doppler-shift frequency.

2
Q

Baseline shift

A

Movement of the zero Doppler shift frequency or zero flow speeds line up or down on a spectral display.

3
Q

Bernoulli effect

A

Pressure reduction in a region of high-flow speed

4
Q

Bidirectional

A

Indicating Doppler instrument capable of distinguishing between positive and negative Doppler shift (approaching and receding flow).

5
Q

Clutter

A

Noise in the Doppler signal that generally is caused by high amplitude, Doppler-shifted echoes from the heart or vessel walls.

6
Q

Color-Doppler display

A

The presentation of two dimensional, real time Doppler shift information in color superimposed on a real-time grayscale, anatomic, cross-sectional image. Flow directions toward and away from transducer are presented as different colors on the display.

7
Q

Compliance

A

Distensibility; non-rigid stretchability a vessels.

8
Q

Continues-wave Doppler

A

A Doppler device or procedure that uses continuous wave ultrasound.

9
Q

Cosine

A

The cosine angle A in figure C – 1 is the length of side B divided by the length of side see. Abbreviated COS.

10
Q

Disturbed flow

A

Flow that cannot be described by straight, parallel streamlines.

11
Q

Doppler angle

A

The angle between the sound beam and the flow direction.

12
Q

Doppler effect

A

A change in frequency caused by reflector motion.

13
Q

Doppler equation

A

The mathematical description of the relationship between Doppler shift, frequency, Doppler angle, propagation speed, and reflector speed.

14
Q

Doppler-power display

A

Color Doppler display in which colors are assigned according to the strength (amplitude, power, intensity, energy) of the Doppler shifted echoes.

15
Q

Doppler shift

A

Reflected frequency minus incident frequency; the change in frequency caused by motion.

16
Q

Doppler spectrum

A

The rate of frequencies present and Doppler shift it echoes.

17
Q

Duplex instrument

A

And ultrasound instrument that combines grayscale sonography with pulsed Doppler and, possibly, continuous wave Doppler.

18
Q

Eddies

A

Regions of circular flow patterns present in turbulence.

19
Q

Ensemble length

A

Number of pulses used to generate one color – Doppler image scan line.

20
Q

Fast Fourier transform

A

Digital computer inflammation of the Fourier transform.

21
Q

Filter

A

And electric circuit that passes frequency within a defined range.

22
Q

Flow

A

To move in a stream; volume flow rate.

23
Q

Fluid

A

A material that flows and conforms to the shape of its container; a gas or liquid.

24
Q

Frequency spectrum

A

The range of Doppler shift frequency’s present in the returning echoes.

25
Q

Gate

A

A device that allows only a goes from a selected depth to pass.

26
Q

Hue

A

The color precede based on the frequency of light.

27
Q

Inertia

A

Resistance to acceleration.

28
Q

Laminar flow

A

Flow in which fluid layers slide over each other in a smooth, orderly manner, with no mixing between layers.

29
Q

Luminance

A

Brightness of a presented Hue and saturation.

30
Q

Parabolic flow

A

Laminar flow with a profile in the shape of a parabola.

31
Q

A

Two signals differing by one fourth of a cycle.

32
Q

Plug flow

A

Flow with all fluid portions traveling with the same flow speed and direction.

33
Q

Poise

A

Unit of viscosity.

34
Q

Poiseuille equation

A

The mathematical description of the dependence of Volume flow rate on pressure, vessel length and radius and fluid viscosity.

35
Q

Priority

A

The gray – scale echo strength below which color – Doppler information is shown preferentially on a display.

36
Q

Pulsatile flow

A

Flow that accelerates and decelerates with each cardiac cycle.

37
Q

Pulsed Doppler

A

A Doppler device or procedure that uses pulsed – wave ultrasound.

38
Q

Range gating

A

Selection of the depth from which echoes are excepted based on echo arrival time.

39
Q

Resistance

A

Pressure difference divided by volume flow rate for steady flow.

40
Q

Sample volume

A

The anatomic region from which pulsed Doppler echoes are accepted.

41
Q

Saturation

A

The amount of hue present in a mix with white.

42
Q

Spectral analysis

A

Separation of frequencies in a Doppler signal for display as a doubler spectrum; the application of the Fourier transform to determine the frequency components present in a Doppler signal.

43
Q

A

Why didn’t of the Doppler shift spectrum; that is, the increase in the range of Doppler shift frequency’s present that occurs because of a broad and range of flow velocities encountered by the sound being. This occurs for disturbed and turbulent flow.

44
Q

Spectral-Doppler display

A

The presentation of Doppler information in a quantitive form of Doppler shift versus time. Visual display of a Doppler spectrum.

45
Q

Spectral analyzer

A

A device that derives a frequency spectrum from a complex signal.

46
Q

Stenosis

A

Narrowing of a vessel lumen.

47
Q

Streamline

A

A line representing the path of motion of a particle of fluid.

48
Q

Turbulence

A

Random, chaotic, multidirectional flow of a fluid with mixing between layers; flow that is not laminar.

49
Q

Variance

A

Square of standard deviation; one of the outputs of the auto correction process; a measure of spectral broadening.

50
Q

Viscosity

A

Resistance of a fluid to flow.

51
Q

Volumetric flow rate

A

Fiamm of fluid passing a point per unit of time.

52
Q

Wall filter

A

And electric filter that passes frequencies above a set level and eliminates strong, low-frequency Doppler shift from pulsating heart or vessel walls or tissue motion.

53
Q

Window

A

An anechoic region appearing the need echo frequencies presented on a Doppler spectral display.