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MRI > Test 1 > Flashcards

Test 1 Flashcards

1
Q

Atoms with odd mass number is considered ___

A

MR active

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2
Q

What two components must a vector have?
A. Energy and speed
B. Mass and charge
C. Magnitude and direction
D. Phase and frequency

A

C

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3
Q

opposing vectors with the same magnitude will ___
a. cancel out
b. double

A

A

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4
Q

vectors with the same magnitude and direction___
a. cancel out
b. double

A

B

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5
Q

Electric charge is measured in ___
a. Coulombs (C)
b. Amps (A)
c. Ohms
d. Volts (V)

A

A

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6
Q

Resistance is measured in __
a. Coulombs (C)
b. Amps (A)
c. Ohms
d. Volts (V)

A

C

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7
Q

Electric current is measured in ____
a. Coulombs (C)
b. Amps (A)
c. Ohms
d. Volts (V)

A

B

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8
Q

Voltage is measured in ____
a. Coulombs (C)
b. Amps (A)
c. Ohms
d. Volts (V)

A

D

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9
Q

___ is the friction that impedes flow of electrons
a. resistance
b. electric current
c. electric charge
d. voltage

A

A

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10
Q

___ is electric potential
a. resistance
b. electric current
c. electric charge
d. voltage

A

D

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11
Q

____ is the movement of electric charge
a. resistance
b. electric current
c. electric charge
d. voltage

A

B

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12
Q

Ohm’s law is used to calculate relationship between ___ , ____ and ____

A

voltage, current, resistance

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13
Q

Ohm’s Law equation

A

V = IR

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14
Q

Power is the measurement of ____ per ___

A

work
time

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15
Q

what are 4 electrical states of matter

A

insulator
conductor
superconductor
semiconductor

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16
Q

which electrical state of matter resist flow of electron?
a. insulator
b. conductor
c. superconductor
d. semiconductor

A

A

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17
Q

which electrical state of matter allows flow of electron with some difficulty?
a. insulator
b. conductor
c. superconductor
d. semiconductor

A

B

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18
Q

which electrical state of matter can behave as an insulator or conductor
a. insulator
b. conductor
c. superconductor
d. semiconductor

A

D

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19
Q

which electrical state of matter freely allows flow of electrons with zero resistance?
a. insulator
b. conductor
c. superconductor
d. semiconductor

A

C

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20
Q

every magnet contains a north and south pole called ____

A

dipole

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21
Q

Like poles ___
Unlike poles ___

A

repel
attract

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22
Q

magnetic flux lines leaves the ___ pole and returns the ___ pole

A

north
south

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23
Q

magnetic field is measured in ____

A

Tesla (T) & Gauss (S)

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24
Q

what is magnetic susceptibility

A

the degree a material is magnetized by a magnetic field

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25
Q

what determine magnetic susceptibility

A

electron configuration

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26
Q

what are 3 types of magnetic susceptibility

A

Diamagnetism
Paramagnetism
Ferromagnetism

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27
Q

___ is slightly repelled by external magnetic field
a. Diamagnetism
b. Paramagnetism
c. Ferromagnetism

A

A

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28
Q

___ is slightly attracted by external magnetic field
a. Diamagnetism
b. Paramagnetism
c. Ferromagnetism

A

B

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29
Q

___ is strongly attracted to external magnetic field
a. Diamagnetism
b. Paramagnetism
c. Ferromagnetism

A

C

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30
Q

which type of magnetic susceptibility retains magnetism when removed from external field?
a. Diamagnetism
b. Paramagnetism
c. Ferromagnetism

A

C

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31
Q

Determine magnetic susceptibility of
a. Diamagnetism ____
b. Paramagnetism ____
c. Ferromagnetism ____

A

a. low negative
b. low positive
c. high positive

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32
Q

Iron & Steel are examples of ____
a. Diamagnetism
b. Paramagnetism
c. Ferromagnetism

A

C

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33
Q

Copper, Lead, and Water are examples of ___
a. Diamagnetism
b. Paramagnetism
c. Ferromagnetism

A

A

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34
Q

Gadolinium, aluminum, tungsten are examples of ____
a. Diamagnetism
b. Paramagnetism
c. Ferromagnetism

A

B

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35
Q

An electron in motion has both ___ & ____

A

electric and magnetic field

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36
Q

As current increases = strength of magnetic field ___ (increase/decrease)

A

increase

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37
Q

If a wire is bent to form loops, what is formed?

A

solenoid

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38
Q

what is created when there is a rod of ferromagnetic material placed inside the solenoid

A

electromagnet

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39
Q

If a rod of ferromagnetic material placed inside a solenoid, would the intensity of magnetic field increase or decrease

A

increase

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40
Q

what is Faraday’s Law

A

describe how a moving magnet can induce charge in a coil of wire

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41
Q

3 main components of Faraday’ Law

A

motion
charge
magnetism

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42
Q

A moving electric charge will ____

A

induce magnetic field

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43
Q

A moving magnet will ___

A

induce charge in wire

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44
Q

When a moving charge slows down or speed up, photon is emitted - what kind of photon is this?
a. Bremss
b. Characteristic

A

A

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45
Q

high frequency = ___wavelength

A

short

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46
Q

90 degree to external magnetic field is ____
a. longitudinal plane
b. transverse plane

A

B

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47
Q

direction of magnetic field is ____
a. longitudinal plane
b. transverse plane

A

A

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48
Q

what are 2 components of MRI instrumentation

A

RF transmit coil
RF receiver coil

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49
Q

Function of RF transmit coil ____
a. manipulate hydrogen
b. detect signal from patient

A

A

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50
Q

Function of RF receiver coil ____
a. manipulate hydrogen
b. detect signal from patient

A

B

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51
Q

Which of the following is not a characteristic of MR Active nuclei?
a. spins do not cancel out
b. odd mass number
c. angular momentum
d. even mass number

A

D

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52
Q

protons and neutrons spin cancel each other out when there are the same number of ____ & ___

A

protons
neutrons

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53
Q

2 main components of MR Active Nuclei

A
  1. electrical charge
  2. spinning (motion)
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54
Q

MR active nuclei automatically acquire a ____

A

magnetic field

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55
Q

The magnetic field acquired by MR active nuclei is called___

A

magnetic moment

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56
Q

The isotope of hydrogen is called __

A

protium

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57
Q

what happened to MR active nuclei when there is no external magnetic field applied

A

randomly oriented and cancel each other out

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58
Q

What happened to MR active nuclei when there is an external magnetic field applied

A

align with B0

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59
Q

what are 2 ways that MR active nuclei align with external magnetic field

A
  1. spin up
  2. spin down
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60
Q

if MR nuclei spin up, the energy is ___
a. low
b. high

A

A

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61
Q

if MR nuclei spin down, the energy is ____
a. low
b. high

A

B

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62
Q

There are always more ____ energy aka ____ at equilibrium
a. low - parallel
b. high - antiparallel
c. low - antiparallel
d. high -parallel

A

A

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63
Q

more magnetic moments spin ____

A

up

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64
Q

As B0 increases, ___ hydrogen have the energy to oppose B0 (less/more)

A

less

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65
Q

As B0 increases, more H spin ___

A

up

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66
Q

the MR nuclei wobble around ___

A

B0 (external magnetic field)

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67
Q

What is the gyromagnetic ratio of hydrogen?
a. 21.28 MHz/T
b. 63.86 MHz/T
c. 127.71 MHz/T
c. 42.57 MHz/T

A

c. 42.57 MHz/T

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68
Q

At equilibrium, there are always more _________ nuclei when aligned in a magnetic field.

      I. Low energy

      II. High Energy

      III. Spin up

a. I and II
b. I and III
c. I, II, and III
d. III

A

B

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69
Q

What is the larmor equation?
a. Precessional frequency = gyromagnetic ratio * field strength
b. MHz = MHz/T * T
c. ω0 = γ * B0
d. All the above

A

D

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70
Q

What is precessional phase

A

position of each magnetic moment on its precessional path

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71
Q

at equilibrium, spins will be ___ (out of phase/ inphase)

A

out of phase

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72
Q

what is precessional frequency

A

time it takes one revolution around precessional path

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73
Q

unit for frequency

A

Hz

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74
Q

What does lamor equation determine

A

speed at which H precess

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75
Q

In the larmor equation - ω0 = γ * B0 ,
what does each component stand for and its unit

A

ω0 = larmor frequency (Hz)
γ = gyromagnetic ratio of H - 42.57 MHz/T
B0 = external mag field (T)

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76
Q

Resonance in MRI is achieved when ___

A

EM pulse emitted at the larmor frequency of H

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77
Q

another name for EM pulse

A

RF excitation pulse (B1)

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78
Q

B1 (RF pulse ) is 90 degree to ____
a. B0 - longitudinal
b B0 - transverse

A

B

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79
Q

MR active nuclei only resonates when ____

A

its precessional frequency matches the frequency of RF pulse

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80
Q

Excitation causes H to gain more energy resulting in more _____
a. spin down ( high E, antiparallel)
b. spin up ( low E , parallel)

A

A

81
Q

Excitation moves ____ away from ___ plane into ___ plane

A

NMV
longitudinal
transverse

82
Q

The NMV can only be measured by flipping magnetization:
a. in the +Z direction axis
b. 90º to the transverse plane
c. in the transverse plane
d. in the longitudinal plane

A

C

83
Q

When there is excitation, MR nuclei become ____
a. inphase
b. dephase

A

A

84
Q

after a 90 degree excitation pulse, H are ____ and precess fully in __ plane
a. dephase - longitudinal
b. inphase - transverse

A

B

85
Q

How is a MR signal is detected

A
  1. H is coherent in transverse plane
  2. Place coil near it
  3. electric current produced
  4. voltage produced is MR signal
86
Q

signal frequency of MR depends on ___

A

rotation of NMV

87
Q

signal magnitude of MR depends on ___

A

amount of coherent magnetization on transverse plane

88
Q

For a MR nuclei to resonate what are needed? (3)

A

strong B0
H precess fast
high frequency RF pulse

89
Q

More signal = ___ NMV = _____ energy H

A

large
low

90
Q

Resonance results in ___ & ___

A

excitation & coherence

91
Q

If NMV only can be measured when they move toward transverse plane, then RF pulse needed to be ___ and the flip angle need to be____

A

a. strong or longer
b. larger

92
Q

______ magnetization produce MR signal
a. coherent transverse
b. incoherent transverse
c. coherent longitudinal
d. Incoherent transverse

A

A

93
Q

FID ( free induction decay) is produced when ___
a. excited and inphase
b. relax and dephase

A

B

94
Q

what form part pulse sequences

A

magnitude
timing of RF pulse

95
Q

what are the cons of MRI (3)

A

long scan time
expensive
complex

96
Q

pros of MRI (4) - which is the main pros

A

no ionizing radiation
multiplanar
multiparametric
contrast resolution ***

97
Q

why contrast resolution is a primary advantage for MRI

A

visualize soft tissue

98
Q

THe ability to distinguish between two points as separate and distinct is ____
a. spatial resolution
b. contrast resolution

A

A

99
Q

The ability to distinguish adjacent soft tissues from one another is ___

a. spatial resolution
b. contrast resolution

A

b

100
Q

what are two main factors that can determine image contrast

A

intrinsic or extrinsic contrast parameter

101
Q

which contrast parameter can be controlled by technologist

A

extrinsic

102
Q

density of bone will be considered ____
a. extrinsic contrast
b. intrinsic contrast

A

B

103
Q

T1 time, T2 time, PD, flow, ADC will be considered ____
a. extrinsic contrast
b. intrinsic contrast

A

B

104
Q

TR, TE, Flip angle, TI, ETL, b value will be considered ____
a. extrinsic contrast
b. intrinsic contrast

A

A

105
Q

which of the following is NOT intrinsic contrast parameter?
a. T1 time
b. TR
c. PD
d. ADC

A

B

106
Q

which of the following is NOT extrinsic contrast parameter
a. TR
b. TE
c. T2 time
d. b value

A

C

107
Q

what happened when RF pulse is turned off ? (2)

A
  1. H realign with B0
  2. magnetic moment dephase
108
Q

T1 recovery in ___ plane

A

longitudinal

109
Q

T2 decay in ___ plane

A

transverse

110
Q

T1 recovery is caused by ____
a. nuclei giving up energy to surrounding env
b. nuclei’s magnetic field bumps into each other

A

A

111
Q

T2 decay is caused by ____
a. nuclei giving up energy to surrounding env
b. nuclei’s magnetic field bumps into each other

A

B

112
Q

Spin-lattice relaxation refers to ____

A

T1

113
Q

Spin-spin relaxation refers to ____

A

T2

114
Q

would T1 recovery or T2 decay also cause the nuclei to dephase?

A

T2

115
Q

T1 recovery is the time it takes a tissue to ____

A

recover 63% of its longitudinal magnetizaton

116
Q

T2 decay is the time it takes a tissue to ___

A

decay/ dephase 63% of its transverse magnetization

117
Q

Amount of T1 is controlled by ____
Amount of T2 is controlled by ____

A

TR
TE

118
Q

Which process is faster ? T1 recovery or T2 decay

A

T2 decay

119
Q

A tissue has a high signal if ____

A

it has a large transverse component of coherent mag at TE.

120
Q

high signal = ____ bright/dark

A

BRIGHT

121
Q

images produced constantly mainly thru which 2 factors

A

1/ proton density
2/ T1 recovery - T2 decay

122
Q

3 primary mechanisms of T1/T2 to produce contrast in different tissue

A
  1. inherent energy of tissue
  2. how close molecules are
  3. matching larmor frequency
123
Q

In T1, which mechanism is important in how contrast is generated?
1. inherent energy of tissue
2. how close molecules are
3. matching larmor frequency

A

1

124
Q

In T2, which mechanism is important in how contrast is generated?
1. inherent energy of tissue
2. how close molecules are
3. matching larmor frequency

A

2

125
Q

a better contrast is generated in T1 if the tissue has ____ inherent energy (low/high)

A

low

126
Q

a better contrast is generated in T2 if the tissue has molecules that are ___ (close, far away)

A

close

127
Q

Tissues with short T1 time appears___ on ___ image

A

bright
T1-weight

128
Q

Tissues with short T2 time appears ___ on ___

A

bright
T2-weight

129
Q

In T1,
fat will have _____ T1 time
water will have___ T1 time

A

short
long

130
Q

why fat has a short T1 time

A

inherent energy of H is low and larmor frequency matches with its longitudinal magnetization

131
Q

why water has a long T1 time

A

inherent energy of H is high and larmor frequency is slightly faster than its longitudinal magnetization

132
Q

Fat in T1 look ___ (bright/dark)

A

BRIGHT

133
Q

Water in T1 look ___ (bright/dark)

A

DARK

134
Q

Fat in T2 look ___ (bright/dark)

A

dark

135
Q

Water in T2 look ___ (bright/dark)

A

bright

136
Q

A good contrast for T1 need a ____
a. short TR
b. short TE
c. long TR
d. long TE

A

A & B

137
Q

A good contrast for T2 need a ____
a. short TR
b. short TE
c. long TR
d. long TE

A

C & D

138
Q

A good contrast for PD need a ____
a. short TR
b. short TE
c. long TR
d. long TE

A

B & C

139
Q

If water/fluid looks white, the image is __

A

T2

140
Q

if water/fluid looks dark, the image is ___

A

T1

141
Q

Magnetization of XY PLANE is ____ plane

A

TRANSVERSE

142
Q

T2 time of fat is ___

A

short

143
Q

T2 time of water is ____

A

long

144
Q

Why do we need a short TR for T1 images

A

short TR so there will be differences in tissue relaxation. if TR is too long, all tissues will fully recover

145
Q

Fat has __ (low/high) signal on T1

A

high

146
Q

Why do we need a long TE for T2 contrast

A

to measure difference in T2 decay and to allow enough time to pass so different tissues can dephase before signal is read.

147
Q

Tissues with a high PD are ____ (bright/dark)

A

bright

147
Q

Tissues with low PD are ____ (bright/dark)

A

DARK

147
Q

By altering ___ contrast parameters we can alter the type of contrast present
a. extrinsic
b. intrinsic

A

A

148
Q

T1 weighting requires ____ ____ to capture T1 effects before vectors are allowed to fully recover
a. short - TE
b. short - TR
c. long - TE
d. long TR

A

B

149
Q

T1 weighting requires ___ ___ to reduce T2 effects
a. short - TE
b. short - TR
c. long - TE
d. long TR

A

A

150
Q

T2 weighting requires ___ ____ to give time for vectors in different tissues to dephase
a. short - TE
b. short - TR
c. long - TE
d. long TR

A

C

151
Q

T2 weighting requires ___ ___ to reduce T1 effects
a. short - TE
b. short - TR
c. long - TE
d. long TR

A

D

152
Q

which of the following is needed to make a PD-w image?
a. long TR
b. short TR
c. long TE
d. short TE
e. B & D
f. A & C
g. A & D

A

E - short TE & long TR

153
Q

●Short TR = 300ms-700ms
● Long TR = ≥2000ms
● Short TE = 10ms-30ms
● Long TE = 80ms
What would be the weighting of an image with:
- TR of 2000ms and a TE of 80ms?

A

T2

154
Q

●Short TR = 300ms-700ms
● Long TR = ≥2000ms
● Short TE = 10ms-30ms
● Long TE = 80ms
What would be the weighting of an image with
-TR of 2000ms and a TE of 20ms?

A

PD

155
Q

●Short TR = 300ms-700ms
● Long TR = ≥2000ms
● Short TE = 10ms-30ms
● Long TE = 80ms
What would be the weighting of an image with
- TR of 500ms and a TE of 80 ms?

A

Poor Contrast

156
Q

●Short TR = 300ms-700ms
● Long TR = ≥2000ms
● Short TE = 10ms-30ms
● Long TE = 80ms
What would be the weighting of an image with
- TR of 500ms and a TE of 20ms?

A

T1

157
Q

The recovery of longitudinal magnetization due to spin-lattice relaxation is ___
a. T1
b. T2

A

T1

158
Q

The decay of coherent transverse magnetization due to spin-spin relaxation is ____
a. T1
b. T2

A

T2

159
Q

___ is the movement of molecules in the
extracellular space due to random thermal motion

A

Diffusion

160
Q

tissues have ADC which is ____
a. extrinsic contrast parameter
b. intrinsic contrast parameter

A

B

161
Q

what does ADC stand for

A

apparent diffusion coefficient

162
Q

what is ADC

A

net displacement of molecules across an area of tissues per sec

163
Q

DWI or diffusion -weighted imaging measures ____

A

the differences in ADC

164
Q

what does b value determine

A

amount of diffusion weighting

165
Q

MRI use ____ to measure ADC

A

2 gradients ( one to rephase, another dephase)

166
Q

High ADC = dephase ___ (more/less)= ___ signal (high/low)

A

more - low

167
Q

Low ADC = dephase ___ (more/less)= ___ signal (high/low)

A

less - high

168
Q

stronger diffusion gradients = ____ b value (high/low)

A

high

169
Q

TO acquire a DWI, how many directions must be measured

A

3 (AP, RL, SI)

170
Q

b-value of 0 = ___-weighted

A

T2

171
Q

T2 shine through is when __

A

pathology with hyperintense T2 signal appear white on DWI can be mistaken for acute stroke.

172
Q

ADC map can be created using ___ & ___

A

B0
DWI images

173
Q

if ADC is high, water will appear ___ on DWI

A

DARK

174
Q

if ADC is low, water will appear __ on DWI

A

BRIGHT

175
Q

what is the purpose of SWI

A

highlight differences between magnetic susceptibility of tissues

176
Q

____ is helpful in imaging brain bleed
a. DWI
b. T1-w
C. SWI
d. fMRI

A

SWI

177
Q

___ is used to measure brain activity
a. DWI
b. T1-w
C. SWI
d. fMRI

A

D

178
Q

fMRI use ____ to create contrast

A

BOLD (blood oxygenation level dependent)

179
Q

___ blood causes more dephasing
a. deoxygenated
b. oxygenated

A

A

180
Q

less dephasing = ___ signal (increase/decrease)

A

increased

181
Q

relaxivity is the ability to ___

A

change the relaxation times of tissues

182
Q

The higher the relaxivity, the ___ it appear on image (brighter/darker)

A

brIghter

183
Q

what is the most common contrast agent?

A

Gadolinium - T1 agents

184
Q

what is the purpose of pulse sequences

A

rephase magnetic moment to produce an echo of the FID

185
Q

what are the 2 types of pulse sequence

A

spin-echo
gradient-echo

186
Q

___-echo pulse sequence use 180 RF
a. spin
b. gradient

A

A

187
Q

Pulse sequence uses ___ & ___, and they are timed to control the weighting

A

RF pulse
gradients

188
Q

The ___ nuclei needed to be ___ to create a signal

A

transverse coherent
rephase

189
Q

what is the command to turn around for spin-echo pulse sequence

A

180 RF rephasing pulse

190
Q

spin-echo occurs at time ___

A

TE

191
Q

In SE, TR is the time between ___
a. 90 degree excitation pulses
b. 90 degree excitation pulse and peak of the echo

A

A

192
Q

In SE, TE is the time between ___
a. 90 degree excitation pulses
b. 90 degree excitation pulse and peak of the echo

A

B

193
Q

what is TAU

A

time between 90 degree excitation pulse and 180 RF pulse

194
Q

in CSE,how many rephasing pulses are used to get a T1 image?

A

1

195
Q

in CSE, how many rephasing pulses are used to get a PD & T2 image?

A

2

196
Q

pros & cons of CSR

A

pro: true T2 weighting
con: long time scan

197
Q
A

MRI (5 decks)

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