Test 1 Flashcards
1
Q
Atoms with odd mass number is considered ___
A
MR active
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
3
Q
opposing vectors with the same magnitude will ___
a. cancel out
b. double
A
A
4
Q
vectors with the same magnitude and direction___
a. cancel out
b. double
A
B
5
Q
Electric charge is measured in ___
a. Coulombs (C)
b. Amps (A)
c. Ohms
d. Volts (V)
A
A
6
Q
Resistance is measured in __
a. Coulombs (C)
b. Amps (A)
c. Ohms
d. Volts (V)
A
C
7
Q
Electric current is measured in ____
a. Coulombs (C)
b. Amps (A)
c. Ohms
d. Volts (V)
A
B
8
Q
Voltage is measured in ____
a. Coulombs (C)
b. Amps (A)
c. Ohms
d. Volts (V)
A
D
9
Q
___ is the friction that impedes flow of electrons
a. resistance
b. electric current
c. electric charge
d. voltage
A
A
10
Q
___ is electric potential
a. resistance
b. electric current
c. electric charge
d. voltage
A
D
11
Q
____ is the movement of electric charge
a. resistance
b. electric current
c. electric charge
d. voltage
A
B
12
Q
Ohm’s law is used to calculate relationship between ___ , ____ and ____
A
voltage, current, resistance
13
Q
Ohm’s Law equation
A
V = IR
14
Q
Power is the measurement of ____ per ___
A
work
time
15
Q
what are 4 electrical states of matter
A
insulator
conductor
superconductor
semiconductor
16
Q
which electrical state of matter resist flow of electron?
a. insulator
b. conductor
c. superconductor
d. semiconductor
A
A
17
Q
which electrical state of matter allows flow of electron with some difficulty?
a. insulator
b. conductor
c. superconductor
d. semiconductor
A
B
18
Q
which electrical state of matter can behave as an insulator or conductor
a. insulator
b. conductor
c. superconductor
d. semiconductor
A
D
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
20
Q
every magnet contains a north and south pole called ____
A
dipole
21
Q
Like poles ___
Unlike poles ___
A
repel
attract
22
Q
magnetic flux lines leaves the ___ pole and returns the ___ pole
A
north
south
23
Q
magnetic field is measured in ____
A
Tesla (T) & Gauss (S)
24
Q
what is magnetic susceptibility
A
the degree a material is magnetized by a magnetic field
25
what determine magnetic susceptibility
electron configuration
26
what are 3 types of magnetic susceptibility
Diamagnetism
Paramagnetism
Ferromagnetism
27
___ is slightly repelled by external magnetic field
a. Diamagnetism
b. Paramagnetism
c. Ferromagnetism
A
28
___ is slightly attracted by external magnetic field
a. Diamagnetism
b. Paramagnetism
c. Ferromagnetism
B
29
___ is strongly attracted to external magnetic field
a. Diamagnetism
b. Paramagnetism
c. Ferromagnetism
C
30
which type of magnetic susceptibility retains magnetism when removed from external field?
a. Diamagnetism
b. Paramagnetism
c. Ferromagnetism
C
31
Determine magnetic susceptibility of
a. Diamagnetism ____
b. Paramagnetism ____
c. Ferromagnetism ____
a. low negative
b. low positive
c. high positive
32
Iron & Steel are examples of ____
a. Diamagnetism
b. Paramagnetism
c. Ferromagnetism
C
33
Copper, Lead, and Water are examples of ___
a. Diamagnetism
b. Paramagnetism
c. Ferromagnetism
A
34
Gadolinium, aluminum, tungsten are examples of ____
a. Diamagnetism
b. Paramagnetism
c. Ferromagnetism
B
35
An electron in motion has both ___ & ____
electric and magnetic field
36
As current increases = strength of magnetic field ___ (increase/decrease)
increase
37
If a wire is bent to form loops, what is formed?
solenoid
38
what is created when there is a rod of ferromagnetic material placed inside the solenoid
electromagnet
39
If a rod of ferromagnetic material placed inside a solenoid, would the intensity of magnetic field increase or decrease
increase
40
what is Faraday's Law
describe how a moving magnet can induce charge in a coil of wire
41
3 main components of Faraday' Law
motion
charge
magnetism
42
A moving electric charge will ____
induce magnetic field
43
A moving magnet will ___
induce charge in wire
44
When a moving charge slows down or speed up, photon is emitted - what kind of photon is this?
a. Bremss
b. Characteristic
A
45
high frequency = ___wavelength
short
46
90 degree to external magnetic field is ____
a. longitudinal plane
b. transverse plane
B
47
direction of magnetic field is ____
a. longitudinal plane
b. transverse plane
A
48
what are 2 components of MRI instrumentation
RF transmit coil
RF receiver coil
49
Function of RF transmit coil ____
a. manipulate hydrogen
b. detect signal from patient
A
50
Function of RF receiver coil ____
a. manipulate hydrogen
b. detect signal from patient
B
51
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
D
52
protons and neutrons spin cancel each other out when there are the same number of ____ & ___
protons
neutrons
53
2 main components of MR Active Nuclei
1. electrical charge
2. spinning (motion)
54
MR active nuclei automatically acquire a ____
magnetic field
55
The magnetic field acquired by MR active nuclei is called___
magnetic moment
56
The isotope of hydrogen is called __
protium
57
what happened to MR active nuclei when there is no external magnetic field applied
randomly oriented and cancel each other out
58
What happened to MR active nuclei when there is an external magnetic field applied
align with B0
59
what are 2 ways that MR active nuclei align with external magnetic field
1. spin up
2. spin down
60
if MR nuclei spin up, the energy is ___
a. low
b. high
A
61
if MR nuclei spin down, the energy is ____
a. low
b. high
B
62
There are always more ____ energy aka ____ at equilibrium
a. low - parallel
b. high - antiparallel
c. low - antiparallel
d. high -parallel
A
63
more magnetic moments spin ____
up
64
As B0 increases, ___ hydrogen have the energy to oppose B0 (less/more)
less
65
As B0 increases, more H spin ___
up
66
the MR nuclei wobble around ___
B0 (external magnetic field)
67
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
c. 42.57 MHz/T
68
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
B
69
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
D
70
What is precessional phase
position of each magnetic moment on its precessional path
71
at equilibrium, spins will be ___ (out of phase/ inphase)
out of phase
72
what is precessional frequency
time it takes one revolution around precessional path
73
unit for frequency
Hz
74
What does lamor equation determine
speed at which H precess
75
In the larmor equation - ω0 = γ * B0 ,
what does each component stand for and its unit
ω0 = larmor frequency (Hz)
γ = gyromagnetic ratio of H - 42.57 MHz/T
B0 = external mag field (T)
76
Resonance in MRI is achieved when ___
EM pulse emitted at the larmor frequency of H
77
another name for EM pulse
RF excitation pulse (B1)
78
B1 (RF pulse ) is 90 degree to ____
a. B0 - longitudinal
b B0 - transverse
B
79
MR active nuclei only resonates when ____
its precessional frequency matches the frequency of RF pulse
80
Excitation causes H to gain more energy resulting in more _____
a. spin down ( high E, antiparallel)
b. spin up ( low E , parallel)
A
81
Excitation moves ____ away from ___ plane into ___ plane
NMV
longitudinal
transverse
82
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
C
83
When there is excitation, MR nuclei become ____
a. inphase
b. dephase
A
84
after a 90 degree excitation pulse, H are ____ and precess fully in __ plane
a. dephase - longitudinal
b. inphase - transverse
B
85
How is a MR signal is detected
1. H is coherent in transverse plane
2. Place coil near it
3. electric current produced
4. voltage produced is MR signal
86
signal frequency of MR depends on ___
rotation of NMV
87
signal magnitude of MR depends on ___
amount of coherent magnetization on transverse plane
88
For a MR nuclei to resonate what are needed? (3)
strong B0
H precess fast
high frequency RF pulse
89
More signal = ___ NMV = _____ energy H
large
low
90
Resonance results in ___ & ___
excitation & coherence
91
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. strong or longer
b. larger
92
______ magnetization produce MR signal
a. coherent transverse
b. incoherent transverse
c. coherent longitudinal
d. Incoherent transverse
A
93
FID ( free induction decay) is produced when ___
a. excited and inphase
b. relax and dephase
B
94
what form part pulse sequences
magnitude
timing of RF pulse
95
what are the cons of MRI (3)
long scan time
expensive
complex
96
pros of MRI (4) - which is the main pros
no ionizing radiation
multiplanar
multiparametric
contrast resolution ***
97
why contrast resolution is a primary advantage for MRI
visualize soft tissue
98
THe ability to distinguish between two points as separate and distinct is ____
a. spatial resolution
b. contrast resolution
A
99
The ability to distinguish adjacent soft tissues from one another is ___
a. spatial resolution
b. contrast resolution
b
100
what are two main factors that can determine image contrast
intrinsic or extrinsic contrast parameter
101
which contrast parameter can be controlled by technologist
extrinsic
102
density of bone will be considered ____
a. extrinsic contrast
b. intrinsic contrast
B
103
T1 time, T2 time, PD, flow, ADC will be considered ____
a. extrinsic contrast
b. intrinsic contrast
B
104
TR, TE, Flip angle, TI, ETL, b value will be considered ____
a. extrinsic contrast
b. intrinsic contrast
A
105
which of the following is NOT intrinsic contrast parameter?
a. T1 time
b. TR
c. PD
d. ADC
B
106
which of the following is NOT extrinsic contrast parameter
a. TR
b. TE
c. T2 time
d. b value
C
107
what happened when RF pulse is turned off ? (2)
1. H realign with B0
2. magnetic moment dephase
108
T1 recovery in ___ plane
longitudinal
109
T2 decay in ___ plane
transverse
110
T1 recovery is caused by ____
a. nuclei giving up energy to surrounding env
b. nuclei's magnetic field bumps into each other
A
111
T2 decay is caused by ____
a. nuclei giving up energy to surrounding env
b. nuclei's magnetic field bumps into each other
B
112
Spin-lattice relaxation refers to ____
T1
113
Spin-spin relaxation refers to ____
T2
114
would T1 recovery or T2 decay also cause the nuclei to dephase?
T2
115
T1 recovery is the time it takes a tissue to ____
recover 63% of its longitudinal magnetizaton
116
T2 decay is the time it takes a tissue to ___
decay/ dephase 63% of its transverse magnetization
117
Amount of T1 is controlled by ____
Amount of T2 is controlled by ____
TR
TE
118
Which process is faster ? T1 recovery or T2 decay
T2 decay
119
A tissue has a high signal if ____
it has a large transverse component of coherent mag at TE.
120
high signal = ____ bright/dark
BRIGHT
121
images produced constantly mainly thru which 2 factors
1/ proton density
2/ T1 recovery - T2 decay
122
3 primary mechanisms of T1/T2 to produce contrast in different tissue
1. inherent energy of tissue
2. how close molecules are
3. matching larmor frequency
123
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
1
124
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
2
125
a better contrast is generated in T1 if the tissue has ____ inherent energy (low/high)
low
126
a better contrast is generated in T2 if the tissue has molecules that are ___ (close, far away)
close
127
Tissues with short T1 time appears___ on ___ image
bright
T1-weight
128
Tissues with short T2 time appears ___ on ___
bright
T2-weight
129
In T1,
fat will have _____ T1 time
water will have___ T1 time
short
long
130
why fat has a short T1 time
inherent energy of H is low and larmor frequency matches with its longitudinal magnetization
131
why water has a long T1 time
inherent energy of H is high and larmor frequency is slightly faster than its longitudinal magnetization
132
Fat in T1 look ___ (bright/dark)
BRIGHT
133
Water in T1 look ___ (bright/dark)
DARK
134
Fat in T2 look ___ (bright/dark)
dark
135
Water in T2 look ___ (bright/dark)
bright
136
A good contrast for T1 need a ____
a. short TR
b. short TE
c. long TR
d. long TE
A & B
137
A good contrast for T2 need a ____
a. short TR
b. short TE
c. long TR
d. long TE
C & D
138
A good contrast for PD need a ____
a. short TR
b. short TE
c. long TR
d. long TE
B & C
139
If water/fluid looks white, the image is __
T2
140
if water/fluid looks dark, the image is ___
T1
141
Magnetization of XY PLANE is ____ plane
TRANSVERSE
142
T2 time of fat is ___
short
143
T2 time of water is ____
long
144
Why do we need a short TR for T1 images
short TR so there will be differences in tissue relaxation. if TR is too long, all tissues will fully recover
145
Fat has __ (low/high) signal on T1
high
146
Why do we need a long TE for T2 contrast
to measure difference in T2 decay and to allow enough time to pass so different tissues can dephase before signal is read.
147
Tissues with a high PD are ____ (bright/dark)
bright
147
Tissues with low PD are ____ (bright/dark)
DARK
147
By altering ___ contrast parameters we can alter the type of contrast present
a. extrinsic
b. intrinsic
A
148
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
B
149
T1 weighting requires ___ ___ to reduce T2 effects
a. short - TE
b. short - TR
c. long - TE
d. long TR
A
150
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
C
151
T2 weighting requires ___ ___ to reduce T1 effects
a. short - TE
b. short - TR
c. long - TE
d. long TR
D
152
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
E - short TE & long TR
153
●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?
T2
154
●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?
PD
155
●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?
Poor Contrast
156
●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?
T1
157
The recovery of longitudinal magnetization due to spin-lattice relaxation is ___
a. T1
b. T2
T1
158
The decay of coherent transverse magnetization due to spin-spin relaxation is ____
a. T1
b. T2
T2
159
___ is the movement of molecules in the
extracellular space due to random thermal motion
Diffusion
160
tissues have ADC which is ____
a. extrinsic contrast parameter
b. intrinsic contrast parameter
B
161
what does ADC stand for
apparent diffusion coefficient
162
what is ADC
net displacement of molecules across an area of tissues per sec
163
DWI or diffusion -weighted imaging measures ____
the differences in ADC
164
what does b value determine
amount of diffusion weighting
165
MRI use ____ to measure ADC
2 gradients ( one to rephase, another dephase)
166
High ADC = dephase ___ (more/less)= ___ signal (high/low)
more - low
167
Low ADC = dephase ___ (more/less)= ___ signal (high/low)
less - high
168
stronger diffusion gradients = ____ b value (high/low)
high
169
TO acquire a DWI, how many directions must be measured
3 (AP, RL, SI)
170
b-value of 0 = ___-weighted
T2
171
T2 shine through is when __
pathology with hyperintense T2 signal appear white on DWI can be mistaken for acute stroke.
172
ADC map can be created using ___ & ___
B0
DWI images
173
if ADC is high, water will appear ___ on DWI
DARK
174
if ADC is low, water will appear __ on DWI
BRIGHT
175
what is the purpose of SWI
highlight differences between magnetic susceptibility of tissues
176
____ is helpful in imaging brain bleed
a. DWI
b. T1-w
C. SWI
d. fMRI
SWI
177
___ is used to measure brain activity
a. DWI
b. T1-w
C. SWI
d. fMRI
D
178
fMRI use ____ to create contrast
BOLD (blood oxygenation level dependent)
179
___ blood causes more dephasing
a. deoxygenated
b. oxygenated
A
180
less dephasing = ___ signal (increase/decrease)
increased
181
relaxivity is the ability to ___
change the relaxation times of tissues
182
The higher the relaxivity, the ___ it appear on image (brighter/darker)
brIghter
183
what is the most common contrast agent?
Gadolinium - T1 agents
184
what is the purpose of pulse sequences
rephase magnetic moment to produce an echo of the FID
185
what are the 2 types of pulse sequence
spin-echo
gradient-echo
186
___-echo pulse sequence use 180 RF
a. spin
b. gradient
A
187
Pulse sequence uses ___ & ___, and they are timed to control the weighting
RF pulse
gradients
188
The ___ nuclei needed to be ___ to create a signal
transverse coherent
rephase
189
what is the command to turn around for spin-echo pulse sequence
180 RF rephasing pulse
190
spin-echo occurs at time ___
TE
191
In SE, TR is the time between ___
a. 90 degree excitation pulses
b. 90 degree excitation pulse and peak of the echo
A
192
In SE, TE is the time between ___
a. 90 degree excitation pulses
b. 90 degree excitation pulse and peak of the echo
B
193
what is TAU
time between 90 degree excitation pulse and 180 RF pulse
194
in CSE,how many rephasing pulses are used to get a T1 image?
1
195
in CSE, how many rephasing pulses are used to get a PD & T2 image?
2
196
pros & cons of CSR
pro: true T2 weighting
con: long time scan
197
