Chapter 5 VOCAB

Question 1

The wraparound of the spectral or color Doppler display that occurs when the frequency shift exceeds the Nyquist limit; only occurs with pulsed-wave Doppler

Answer 1

Aliasing

Question 2

The tool used to inform the machine what the flow angle is so that velocities can be accurately calculated

Answer 2

Angle correction

Question 3

The color Doppler processing technique that assesses pixels as stationary or in motion

Answer 3

Autocorrelation

Question 4

The operator adjustable dividing line between positive frequency shifts and negative frequency shifts on spectral and color Doppler

Answer 4

Baseline

Question 5

The principle that describes the inverse relationship between velocity and pressure

Answer 5

Bernoulli’s principle

Question 6

The Doppler device that can detect positive and negative Doppler shifts

Answer 6

Bidirectional Doppler

Question 7

The term describing the intensity or luminance of the color Doppler display

Answer 7

Brightness

Question 8

Doppler shift information presented as color(hue) superimposed over the grayscale image

Answer 8

Color Doppler imaging

Question 9

The setting for color Doppler that allows the operator to select frequency shift threshold; it determines whether color pixels should be displayed preferentially over grayscale pixels

Answer 9

Color priority

Question 10

The equation that describes the change in velocity as the area changes in order to maintain the volume of blood flow

Answer 10

Continuity Equation

Question 11

Doppler device that uses continuous-wave ultrasound transmission; a device that consists of two elements, one element is used by the system to constantly transmit sound and the other is used to constantly receive sound

Answer 11

Continuous-wave Doppler

Question 12

The change in the frequency of the received signal related to the motion of the reflector

Answer 12

Doppler effect

Question 13

The equation that explains the relationship of the Doppler frequency shift (FD) to the frequency of the transducer (f), the velocity of the blood (n), the angle of the blood (cos •0), and the propagation speed (c)

Answer 13

Doppler equation

Question 14

Real-time two-dimensional imaging combined with the spectral Doppler display

Answer 14

Duplex

Question 15

The number of pulses per scan line in color Doppler; also referred to as packet size

Answer 15

Ensemble length

Question 16

A mathematical process used for analyzing and processing the Doppler signal to produce the spectral waveform

Answer 16

Fast Fourier Transform

Question 17

The volume of blood per unit time; typically measured in liter per minute (L/m) or milliliter per second (mL/s); represented by the Q symbol

Answer 17

Flow

Question 18

The study of blood flow through the blood vessels of the body

Answer 18

Hemodynamics

Question 19

A term used to describe displayed colors (ex. Red, green, blue)

Answer 19

Hue

Question 20

Describes the relationship between gravity, density of the blood, and distance between an arbitrary reference point

Answer 20

Hydrostatic pressure

Question 21

The flow profile represented by blood that travels in nonmixing layers of different velocities

Answer 21

Laminar flow

Question 22

The brightness of the color Doppler image

Answer 22

Luminance

Question 23

The maximum frequency shift sampled without aliasing; equal to one half the PRF

Answer 23

Nyquist limit

Question 24

The component of the Doppler device that determines positive opposed to negative frequency shifts and, therefore, direction of blood flow

Answer 24

Phase quadrature

Question 25

The flow profile represented by blood typically flowing at the same velocity

Answer 25

Plug flow

Question 26

The law that describes the relationship of resistance, pressure and flow

Answer 26

Poiseuille’s law

Question 27

Doppler mode in which the signal is determined by the amplitude (strength) of the shift, not the shift itself; amplitude is directly proportional to the number of red blood cells; also referred to as amplitude Doppler

Answer 27

Power Doppler

Question 28

The difference between pressures at two points of a blood vessel

Answer 28

Pressure gradient

Question 29

Blood that flows in a pattern representative of the beating heart; with increases and decreases in pressure and blood flow velocity

Answer 29

Pulsatility

Question 30

The number of pulses of sound produced in 1 second

Answer 30

PRF

Question 31

The Doppler technique that uses pulses of sound to obtain Doppler signals from a user specified depth

Answer 31

Pulsed-wave Doppler

Question 32

The gate placed by the operator in the region where Doppler sampling is desired; used with pulsed-wave Doppler

Answer 32

Range gate

Question 33

The downstream impedance to flow; determined by vessel length, radius and viscosity of blood

Answer 33

Resistance

Question 34

The area within the range gate where the Doppler signals are obtained

Answer 34

Sample volume

Question 35

The amount of white added to the hue; the more white there is the less saturated the color

Answer 35

Saturation

Question 36

The filing of the spectral window

Answer 36

Spectral broadening

Question 37

Pathologic narrowing of a blood vessel

Answer 37

Stenosis

Question 38

Chaotic; disorderly flow of blood

Answer 38

Turbulent flow

Question 39

The color Doppler scale with mean velocities displayed vertically on the scale and turbulence displayed horizontally

Answer 39

Variance mode

Question 40

The operator control that eliminates low frequency, high-amplitude signals caused by wall or valve motion; also called high-pass filter

Answer 40

Wall filter