Chapter 4 Penny Flashcards
the wraparound of the spectral of color Doppler display that occurs when the frequency shift exceeds the Nyquist limit; occurs only with pulsed-wave Doppler
aliasing
the tool used to inform the machine what the flow is to that the velocities can be accurately calculated
angle correction
the color Doppler processing technique that assesses pixels as stationary or in motion
autocorrelation
the acronym used to describe color-Doppler display; “blue away, red toward’
BART
the operator-adjustable dividing line between positive frequency shifts and negative frequency shifts on spectral and color Doppler
baseline
the principle that describes the inverse relationship between velocity and pressurew
Bernouli’s principle
the Doppler device that can detect positive and negative Doppler shifts
bidirectional Doppler
the stationary layer of blood cells immediately adjacent to the vessel wall
boundary layer
the term describing the intensity or luminance of the color Doppler display
brightness
the muscles in the calf that, upon contraction, propel venous blood toward the heart
calf muscle pump
the ability of veins to store blood
capacitance
acoustic noise in the color and/or spectral Doppler signal
clutter
accessory vessels that connect portions of the same blood vessel together
collateral blood vessels
Doppler shift information presented as a color (hue) superimposed over the grayscale image
color Doppler imaging
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
color priority
the equation that describes the change in velocity as the area changes in order to maintain the volume of blood flow
continuity equation
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
continuous-wave Doppler
the point at which a stenosis is hemodynamically significant with a pressure drop distal to the stenosis
critical stenosis
the inability to determine the depth of the reflector if the pulses are sent out too fast for them to be timed
depth ambiguity
the relaxation of the heart following contraction
diastole
the change in the frequency of the received signal related to the motion of reflector
Doppler effect
the equation that explains the relationship of the Doppler frequency shift to the frequency of the transducer, the velocity of the blood, the angle of blood flow, and the propagation speed
Doppler equation
real-time two-dimensional imaging combined with the spectral Doppler display
duplex
the sum of the individual resistances when multiple vessels are connected in series
effective resistance
the difference in energy between two points
energy gradient
the number of pulses per scan line in color Doppler; also referred to as packet size
ensemble length
pressure applied to the outside of an object
extrinsic pressure
a mathematical process used for analyzing and processing the Doppler signal to produce the spectral waveform
fast Fourier transform
a motion artifact caused by the movement of tissue when using power Doppler
flash artifact
the volume of blood per unit time; typically measured in liter per minute or milliliter per second, represented the symbol Q
flow
the difference between the transmitted and received frequencies
frequency shift
a form of resistance, caused by two materials rubbing against each other, thereby converting energy to heat
friction
critical stenosis
hemodynamically significant stenosis
the study of blood flow through the blood vessels of the body
hemodynamics
a term used to describe displayed colors
hue
describes the relationship between gravity, density of the blood, and distance between an arbitrary reference point
hydrostatic pressure
Newton’s principle that states that an object at rest stays at rest and an object in motion stays in motion unless acted on by an outside force
inertia
supplied with nerves
innervated
the energy form of flowing blood
kinetic energy
the flow profile represented by blood that travels in nonmixing layers of different velocities, with the fastest flow in the center and the slowest flow near the vessel walls
laminar flow
the total amount of energy in a system never changes, although it might be in a different form from which it is started
law of conservation of energy
the brightness of the color Doppler image
luminance
millimeters of mercury
mmHg
low-level echoes on the display that do not contribute useful diagnostic information
noise
Doppler device that cannot differentiate between positive and negative frequency shifts
nondirectional Doppler
a stenosis that does not necessarily compromise blood flow to organs or structures
nonhemodynamically significant stenosis
the maximum frequency shift sampled without aliasing; equal to one half the pulse repetition frequency
Nyquist limit
a law used in electronics in which flow is equal to the pressure differential divided by resistance
Ohm’s law
the component of a continuous-wave Doppler devices that produces the voltage that drives the transducer
oscillator
the number of pulses per scan line; also called ensemble length
packet size
the averaging of color frames in order to display blood flow with a long signal-to-noise ratio
persistence
the component of the Doppler device that determines positive opposed to negative frequency shifts and, therefore, direction of blood flow
phase quadrature
the characteristic waveform of peripheral veins; flow is determined by respiratory variations as a result of intrathoracic pressure changes
phasic flow
in arteries, the phasicity describes the shape of the waveform based on the resistiveness of the distal bed
in veins, phasicity describes the flow pattern that results from respiratory variation
phasicity
the flow profile represented by blood typically flowing at the same velocity
plug flow
the law that describes the relationship of resistance, pressure, and flow
Poisuilles law
pressure energy created by the beating heart
potential energy
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
power Doppler
the difference between pressures of two points of a blood vessel
pressure gradient
blood that flows in a pattern representative of the beating heart, with increases and decreases in pressure and blood flow velocity
pulsatility
Doppler measurement used to determine how pulsatile a vessel is over time
Pulsatility index
the number of pulses of sound produced in one second
pulse repetition frequency
the Doppler technique that uses pulses of sound to obtain Doppler signals from a user specified depth
pulsed-wave Doppler
the gate placed by the operator in the region where Doppler sampling is desired; used with pulsed-wave Doppler
range gate
the ability to determine the depth of echoes by timing how long it takes for the echoes to go from the transducer to the reflector and back; utilized by pulsed-wave devices
range resolution
very small reflectors, like red blood cells
Rayleigh scatterers
the downstream impedance to flow; determined by vessel length, vessel radius, and viscosity of blood
resistance
Doppler measurement used to quantitate the resistiveness of the distal bed
resistive index
the formula used to quantitate the presence of turbulence; Reynolds number greater than 2000 typically indicate turbulence
Reynolds number
the area within the range gate where the Doppler signals are obtained
sample volume
the amount of white added to a hue; the more white there is, the less saturated the color
saturation
the spectral Doppler and color Doppler tool that controls the number of pulses transmitted per second to obtain the Doppler information; also known as pulse repetition frequency in spectral Doppler and color Doppler
scale
the method used to obtain the strain information
speckle tracking
the filling of the spectral window
spectral broadening
the area underneath the envelope on the spectral display
spectral window
pathologic narrowing of a blood vessel
stenosis
the changing of the shape of the muscle as it lengthens and contracts
strain
the operator-adjustable spectral Doppler control that increases or decreases the number of heartbeats visualized on the spectral display
sweep speed
the time period of the cardiac cycle when the heart is contracting
systole
an arterial waveform shape with a delayed peak systolic upstroke that indicates proximal obstruction
Tardus parvus
combination of platelets, red blood cells, and fibrin that make up a blood clot
thrombus
color Doppler imaging technique used to document wall motion
tissue Doppler imaging
the difference of pressure inside a vessel compared to the pressure outside of the vessel
transmural pressure
the ability to visualize real-time grayscale, color Doppler, and spectral Doppler simultaneously
triplex
the outer layer of a blood vessel
tunica adventitia
the inner layer of a blood vessel which is closest to the flowing blood
tunica intima
the middle, muscular layer of a blood vessel
tunica media
chaotic, disorderly flow of blood
turbulent flow
the color Doppler scale with mean velocities displayed vertically on the scale and turbulence displayed horizontally
variance mode
a network of small blood vessels that supply blood to the walls of arteries and veins
vasa vasorum
the narrowing of a blood vessel caused by the contraction of the vessel wall
vasoconstriction
the widening of a blood vessel caused by the contraction of the vessel wall
vasodilatation
the color Doppler scale with mean velocities displayed vertically
velocity mode
the energy loss caused by friction
viscous energy
the operator control that eliminates low-frequency, high amplitude signals caused by wall or valve motion; also called high-pass filter
wall filter
the brightness or amplitude of the dots on a B-mode display; the brighter the dots of the spectral waveform, the more red blood cells that make up the signal
z-axis
