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1

Doppler Shift formula

FD = (2 * Vcos0 * f0)/c

2

Matter classifications

gas
liquid
solid

3

Fluids

flow and conform

4

Viscosity

the resistance to flow

5

What is the unit for viscosity

poise = .1 kg/m-s

6

How much higher is the viscosity of blood plasma compared to water?

50%

7

Hemodynamics

The study of blood flow through the vessels and the changes its force stimulates

8

Blood

liquid with solid componenets
Tissue
supplier of nutrients

9

viscosity of water

.0069 poise

10

viscosity of plasma

.01035 poise

11

viscosity of blood

.035 poise

12

viscosity of blood range

.02 - 10 poise

13

pressure formula

F/A

14

What is needed for blood to flow

pressure gradient

high pressure on one end and low pressure on the other end - path of least resistance

15

What happens if there is equal pressures applied to both ends of a liquid filled tube?

NO flow

16

What can generate pressure differences?

pump
gravity

ions crossing a permeable membrane

17

define Pressure

the driving force needed for flow of blood

18

What does a constant driving pressure produce?

steady flow

19

Define Volumetric flow rate

volume of blood passing a point per unit of time

20

Volumetric flow rate formula

Flow rate = V/t

21

If flow resistance increases what happens to volume flow rate?

decreases

22

If pressure difference increases what happens to volume flow rate?

increases

23

Cardiac output

5000 mL/min 5 liters

5 liters circulates all around in 1 min

24

In a static fluid the pressure is ________

omnidirectional

pressure is equal

25

The flow resistance in a long straight tube depends on what?

pressure difference
fluid viscosity
resistance
* tube length (L)
* radius (r)

26

What happens to resistance when length is increased?

increases

27

What happens to resistance when radius is doubled?

decreases by a factor of 4
1/16

28

What happens to resistance when viscosity is increased?

increases

29

Poiseuille's equation

flow = pressure*diameter/ strength*viscosity

steady flow in a long straight tube

30

What happens to flow rate when length is increased?

decreases

31

What happens to flow rate when diameter is increased?

increases

32

What happens to flow rate when viscosity is increased?

decreases

33

What happens to flow rate when pressure difference is increased?

increases

34

define Hydrostatic pressure

Weight of blood pressing against vessles of heart to level of measurement.

35

How is the circulatory pressure measured

patient in supine position, weight of blood is eliminated.

36

What is the average circulatory pressure?

120 mHg

37

Formula for pressure above the heart

circulatory pressure - hydrostatic pressure

above = CP - HP

38

Formula for pressure below the heart

circulatory pressure + hydrostatic pressure

below = CP + HP

39

What is the hydrostatic pressure of the fingers?

What is the pressure at the fingers?

-50 mHg

120 - 50 = 70 mHg

40

What is the hydrostatic pressure of the head?

What is the pressure at the head?

-30 mHg

120 - 30 = 90 mHg

41

What is the hydrostatic pressure of the heart?

What is the pressure at the heart?

0 mHg

120 - 0 = 120 mHg

42

What is the hydrostatic pressure of the knee?

What is the pressure at the knee?

75 mHg

120 + 75 = 195 mHg

43

What is the hydrostatic pressure of the ankle?

What is the pressure at the ankle?

100 mHg

120 + 100 = 220 mHg

44

During inspiration what happens to the venous flow in the legs?

decreases

diaphragm moves down

45

During inspiration what happens to the venous flow to the heart?

increases

diaphragm moves down

46

During expiration what happens to the venous flow in the legs?

increases

diaphragm moves up

47

During expiration what happens to the venous flow to the heart?

decreases

diaphragm moves up

48

What are the types of flow?

plug
laminar
parabolic
disturbed
turbulence
eddies

49

What is plug flow?

card image

at the entrance of, the speed of the fluid is essentially constant across the tube

blood moves as a unit

50

What is laminar flow?

card image

all flow is in same direction

speed varies:
maximum at center and 0 at tube walls

51

what is Parabolic flow?

card image

type of laminar flow

center speed is 2x the average speed of other stream lines.

52

What is Disturbed flow?

card image

Type of laminar flow

when the parallel stream lines is altered due to plaque or bifurcation.

53

Turbulent Flow

card image

Non-laminar flow

random chaotic, occurs at a stenosis

Bruits can be heard

54

What is Bruits?

A sound heard when there is turbulent flow in an artery.

55

What is Eddies flow?

card image

the net blood flow is in a direction of flow but some blood is heading backwards.

56

What is the Reynold's number?

A Unitless number - predictor of turbulence

when reynold's number is 2000 - 2500 turbulence is likely

57

formula for Reynolds #

R# = (average flow speed * diameter * density) / viscosity

58

If diameter increases what happens to the Reynolds #?

Increases

59

If flow speed increases what happens to the Reynolds #?

Increases

60

If density increases what happens to the Reynolds #?

Increases

61

If viscosity increases what happens to the Reynolds #?

Decreases

Viscosity is the only increased variable that decreases Reynolds number

62

Pulsatile Flow

Being directly influenced by the effects of the beating heart with pulsatile variations of increasing and decreasing pressure and flow speed.

63

What does pulsatile flow rate depend on?

Flow impedance
* resistance
Inertia
compliance

64

Windkessel Effect

stretch and squeeze

in the aorta, the aorta valves close preventing backward flow.

The aorta stretches
valve closes
vessel contracts
pushing blood forward

65

Flow reversal

after forward flow,
decrease of pressure and contraction of vesels causes reverse flow

just a little

66

Explain phasic Flow

venous flow is phasic using valves to prevent flow reversal

Below baseline

67

If the vessel is nice :) what happens to flow speed?

attempt to maintain continuity throughout vessel

68

continuity rule

If an area of constriction occurs the flow attempts to keep the same volume

Speed is increased!

69

Stenosis

Due continuity rule, What happens to flow speed if the diameter is halved?

card image

Speed is increased x 4

70

Stenosis

Due continuity rule, What happens to flow speed if the diameter is halved and the flow is parabolic?

Speed is increased x 8

71

Bernoulli's Principle

Increase in velocity is accompanied by a corresponding decrease in pressure

it is this decrease in pressure that causes lift

72

Explain what happens with speed with bernoulli's Principle

card image
73

Explain what happens with pressure with bernoulli's Principle

card image
74

Explain what happens with volume with Bernoulli's Principle

card image
75

Incident Frequency

transmitted frequency

76

Doppler shift

Change in frequency of sound as a result of motion between source and receiver

77

Factors that influence Doppler

Motion of source
Motion of the reflector
Motion of receiver

78

Doppler Shift equals

Reflected Frequency - incident frequency

RF - IF

79

Incident Frequency AKA

sent frequency
transmitted

80

If receiver and transmitted are stationary, explain the Doppler shift.

NO Doppler shift

81

Doppler Shift moving toward you.

card image

Pitch increases

compression of cycles in front of source
receiver hears more cycles per second

82

Is the Doppler shift coming toward you, positive or negative?

card image

Positive

receiver frequency is greater

83

Doppler Shift moving away from you.

card image

spreading of cycles behind the source

receiver hears less cycles per second

84

Is the Doppler shift going away from you, positive or negative?

card image

Negative

receiver is lower

85

What are the factors that influence Doppler?

Motion of source
motion of the reflector
motion of receiver

86

Explain Doppler for DMS.

The source & receiver are the same

only variable is a moving reflector

87

What is Doppler SHift?

series of pulses are fired at a moving RBC

The echoes from a moving RBC will sow difference in the frequencies that returns to the transducer.

88

What is the Doppler Shift equation?

FD = (V * f0)/c

89

What was the error in the original Doppler equation?

Since there were two shifts it did not work a 2* was added to the equation

FD = (2 * V * f0)/c

90

What else causes an error in the Doppler SHift equation?

The angle

91

What is the correct Doppler Shift equation?

FD = (2 * V* cos0 * f0)/c

92

What happens to the Doppler shift when the beam is perpendicular to the direction of blood flow?

Cos 90 = 0

No Doppler shift

93

What happens to the Doppler shift when the beam is parallel to the direction of blood flow?

Cos 0 = 1

Maximum Doppler shift

94

At what angle is the maximum Doppler shift?

90° and 180°

95

If the angle increases what happens to the cosine?

Decreases

96

If the angle increases what happens to the Doppler shift?

Decreases

97

If the angle increases what happens to the flow?

Decreases

98

If the cosine increases what happens to the Doppler shift?

increases

99

What angle does your beam need to be at when you drop your gate into the vessel?

Between -30° and 60°

100

Why is echo able to to obtain correct Doppler shift outside of 30° and 60°?

The wall angle is big enough to rid reflection

101

Why can't the Doppler shift be estimated below -30°?

pulse is lost to reflection

102

Why can't the Doppler shift be estimated above 60°?

too much error

The cosine changes rapidly at large angles

103

What is demodulation in Doppler?

Process of extracting Doppler shift frequency from the transducer frequency

104

If the return echo is 5,010,000 with a 5 Mhz transducer, what is the Doppler frequency?

10 kHz

105

How do you angle correct for Doppler?

Your orientation line must be parallel to the vessel

106

What are the different types of Doppler?

audible
strip chart
spectral
color
power

107

How many pulses in B-mode to write 1 line?

1-3 pulses

108

How many pulses in color flow Doppler to write 1 line?

5 - 30

10 - 20 average

109

Describe the process of color flow Doppler

1. the frame for greyscale is built
2. the frame for color Doppler is built

110

Why is temporal resolution important for Doppler?

Frames need to be built as fast as possible

111

What is color mapping?

the brightness of the dots can be represented by colors other than white/grey

easier on the eyes

112

What is the Doppler shift frequency proportional too?

the number of red blood cells

always enough RBCs even when the patient is anemic

113

Spectral Doppler

spectrum is the entire range of Doppler shift frequencies created

Of the many velocities in a vessel spectral collects them all.

114

Limitations of Color Doppler?

- only shows statistical representation of the entire spectrum

- only demonstrates mean velocities

- angle dependence

- slow frame rates (temporal res takes hit)

- autocorrelation - fast but not fast enouh to demonstrate entire spectrum

115

What are the 3 components of color?

hue
saturation
luminosity

116

What determines hue?

percentage of

red

green

blue

117

What color will equal percentages of each color create?

black

118

What determines saturation?

determined by how much white is added

white is a mixture of all colors

119

is a complete white screen saturated?

yes

120

What is luminosity?

the brightness of saturation & hue

how intense a color is related to the amplitude of signal

121

What does changes in hue, saturation or luminance indicate?

increase in Doppler shift magnitude

122

What is a variance scale?

shows a change in hue from left to right

123

Sign of the cross

toward

velocity - variance

away

124

What is autocorrelation?

preforms demodulation and determines -+ sign

determines the mean velocity

determines the variance

stores that info in the memory

assigns color to pixel with a change in frequency due to motion

125

how many pulses are required for a 1 speed estimate ensemble?

3 pulse minimum

more for improved accuracy

126

Define autocorrelation

a mathematical process that yields Doppler shift information in color Doppler instruments

127

What is the ensemble length?

the number of pulses used for each color scan line

5 - 30

10 - 20 average

128

What is another name for ensemble?

packet size

129

What determines depth?

echo arrival time

130

What determines brightness?

echo intensity or amplitude

131

What does a different returning echo indicate?

motion

132

Variance

a measure of data that is spread around the mean

133

small variance vs. large variance

small differences are measured well
mean values do not represent large differences very well.

134

How do you turn on gate location?

turn on spectral

135

True or False?

A large gate is better than a small gate.

False

136

How do you move gate? size?

select

select again changes size

137

Color flow gain

almost the same as over all gain

increases the amplitude to all colors on screen

138

what do the colors mean on the color map?

flow toward - red
highest Doppler shift - yellow
flow away - blue
highest negative Doppler shift - teal

139

what is another name for color scale?

velocity scale
color bar
color map

140

How do you adjust color scale?

adjust PRF

141

What do the filters do?

allows for elimination of clutter from tissue motion

wall filters - wall thumptilters

142

Why would you adjust wall filters?

calm down mess

143

176 slide 1 & 2

...

144

what is the significance of large ensemble length?

more sensitivity - ability to detect low flow

increase accuracy

decreased temporal resolution

145

smoothing

color averaging 5 or 6 frames then averages

improves sensitivity - ability to detect low flow

146

persistence

aka smoothing

147

What is the priority to be assigned color pixels?

Doppler shift

148

What happens when Doppler shift is set to low priority?

Grayscale is priority

149

color flow doppler threshold

setting the priority

150
card image

velocity mode- color map

151
card image

variance mode

152

What is the disadvantage to Color flow Doppler

Temporal resolution takes a hit.

153

What can you do to make the temporal resolution the best when using color flow Doppler?

make the gate as small as possible

154

What does gain do when using Color Flow Doppler?

increase the amplitude to all colors on a screen

155

What can you do to reduce the aliasing with color flow Doppler?

decrease PRF

156

Color Flow Doppler

What is the purpose for using filters?

allows elimination of clutter from tissue motion

157

What does this?

Exclude Doppler signals with low frequency, and high amplitude from moving tissue, such as a vessel wall.

High pass - Wall filters

AKA Wall thump filters

158

What can you do in color flow doppler to ensure entire waveform is seen.

adjust the baseline

159

What is ensemble length

# of pulses/scan line

160

What happens with a high ensemble length?

more lines = more accuracy

*the ability to detect low flow

161

What happens to temporal resolution when ensemble length is increased

temporal is reduced

162

Color flow doppler

What is smoothing?

5 or 6 frame averaging

improves sensitivity

163

What is another name for smoothing?

persistence

164

Explain color priority.

machine set priorities for processing

Doppler shift tends to main priority

you can set Doppler to low priority which will make grayscale high priority

165

In a steered box find the home and follow color map

...

166

What does power doppler measure?

amplitude

167

List other names for Power Doppler

Color Power Doppler
Ultrasound angio
color doppler energy
color power angio

look for keywords angio and energy and

168

What are the advantages of Power Doppler?

greater sensitivity to low flow
no worry of angles
no aliasing

169

What are the disadvantages of Power Doppler?

No information of velocity or direction
slow frame
flash artifact

170

What are the benefits to pulsed wave Doppler

measure peak velocities
select location (place gate)
adjust sample size
has range resolution

171

What is DF for CW wave Doppler?

100% or 1

172

With CW Doppler what determines the operating frequency?

voltage

173

Disadvantages of CW Doppler

range ambiguity

174

CW Doppler has no damping - narrow bandwidth

...

175

What does large sample volume in CW Doppler cause?

spectral broadening

(filled in)

176

What is the Fast fourier transfomation

mathmatical formula for drawing waveforms
several velocities - several shifts

copulates all and then plots doppler shifts as velocities

177

How do we adjust x axis?

changing sweep speed

178

What is sweep speed?

# of cycles

179

What kind of shift frequency does plug flow have?

single shift - up stroke

as rises band thins
as falls band thickens

180

What do brighter dots on the waveform mean?

more red blood cells

181

z axis

amplitude

182

x axis

velocity

183

minus sign on Doppler shift means

negative doppler shift

184

The area under the envelope is called what?

spectral window

185

Turbulence will cause the spectral envelope to?

fill

186

what causes spectral broadening?

gate too close to the edge
too large a gate (sample)
turbulence

187

What is the relationship between Doppler shift and frequency?

direct

188

How can you get rid of aliasing?

reduce frequency

189

PI

pulsatility Index

190

PI formula

S-D/Mean

191

RI

Resistive Index

192

RI formula

S-D/S

193

A/B Ratio

Systolic Diastolic Ratio

194

Systolic Diastolic Ratio

S/D

195

BAR

D/S Ratio

196

BAR formula

D/S

197

Monophasic

low resistance

hump with side

198

biphasic

middle resistance

hump

199

triphasic

high resistance

pointy

200

True or False

normal triphasic flow can happen during exercise.

true

201

What is triplex imaging

3 on

B-mode
CFD
SD

202

what is Duplex imaging

2 on
B-mode
SD

203

ALiasing

to fast for system

ticket

204

Nyquist limit

1/2 PRF

205

Name the filters

wall thump filter
high pass filter
baseline filter

206

what do filters do

get rid of clutter caused by low amp signals

207

changing the scale changes the ____

PRF

208

PRF is determined by

depth

209

sampling rate should be what to avoid aliasing

fast enough

210

Doppler gain

same as spectral gain

brightness of dot amplitude

broadening clears out with lower gain

211

what angle should be used?

less than 60 degrees

45-60

212

Which type of Doppler uses a gate?

CFD
SD