week 1 final Flashcards
(150 cards)
1
Q
Calculate the scan time for a fast spin echo sequence with the following parameters: TR 500, TE 24, FOV 20cm 224 x 256 matrix, 4 NEX, 5 ETL, 4 mm slice thickness.
A
1 min. 29 sec.
2
Q
The hydrogen proton induces a strong magnetic field because it is:
A
Charged and spinning
3
Q
The more ETL, the more _____________ is needed.
A
TR
4
Q
Energy is most effectively transferred from one system to another when the systems are at:
A
Resonance
5
Q
Which of the following is always on?
A
B0
6
Q
Relaxation Time refers to:
A
Time required for the nuclear spin to return to equilibrium
7
Q
T1 weighted images are characterized by:
A
Bright fat and dark water
8
Q
What level of sedation requires physiological monitoring?
A
All of the above (Parenteral, Enteral, General Anesthesia, Any patient unconscious)
9
Q
Who is responsible for monitoring a patient who is connected to physiological vital signs equipment?
A
Advanced level care personnel such as RN
10
Q
The purpose of a chelating agent such as DTPA is:
A
Neutralize the toxicity of a metal ion
11
Q
What happens to the hydrogen protons when they are placed in a magnetic field?
A
They align parallel or anti-parallel
12
Q
Calculate the scan time for a 3D gradient echo sequence with the following parameters: FOV 16, TR 25, TE 12, 208 x 256 matrix, 1 NEX, 4mm slice thickness, 36 slices.
A
3 min. 7 sec.
13
Q
In MR imaging, the term “spin” refers specifically to the spinning:
A
Nuclei
14
Q
The tiny magnetic field of the hydrogen proton that is induced by spin and charge and has a north and south pole is called:
A
Magnetic moment
15
Q
Calculate the scan time for a fast spin echo sequence with the following parameters: TR 3000, TE 100, 512 x 512 matrix, 2 NEX, 5 mm slice thickness, 18 ETL.
A
2 min. 50 sec.
16
Q
What is the FDA recommended amount of SAR for whole body averaged over 15 minutes?
A
4 W/kg
17
Q
What is the most important safety consideration associated with a quench?
A
Displacement of oxygen
18
Q
The Larmor precessional frequency of hydrogen in a 3T magnet is:
A
127.74 MHz
19
Q
What extrinsic factor controls the amount of T2 decay?
A
TE
20
Q
What is “DRIVE”?
A
A reverse 90-degree pulse
21
Q
Calculate the scan time for a 3D gradient echo sequence with the following parameters: FOV 16, TR 20, TE 9, 192 x 256 matrix, 2 NEX, 5mm slice thickness, 40 slices.
A
5 min. 7sec.
22
Q
What weighted image would be created with the following parameters: TR 15, TE 2, FA 25?
A
T2*
23
Q
GRE T2*-weighted sequences use:
A
Gradient or RF spoiling
24
Q
Dynamic enhanced T1 weighted MRA sequences of the renal arteries are performed with the use of:
A
Incoherent gradient echoes
25
The nucleus of a hydrogen atom contains:
One proton
26
The symbol for the primary static field is:
Bₒ
27
What is the 5 Gauss line?
The magnetic field strength and distance that is safe for a person with any device
28
T1 and T2 relaxation depends on:
Molecular tumbling rate matching Larmor frequency of hydrogen
29
What physiological monitoring device should be employed when a patient is heavily sedated for an MR exam?
All of the above (Pulse oximetry, Blood pressure, ECG)
30
What is NSF?
Nephrogenic systemic fibrosis
31
What is the primary purpose of gradient coils in MRI?
Spatial localization of the MRI signal
32
What is the main function of the RF coil in MRI?
Transmitting and receiving RF pulses
33
What determines the Larmor frequency of hydrogen?
Strength of the external magnetic field
34
What is the most important safety concern associated with MRI?
Ferromagnetic attraction
35
Who can sign the MRI screening form?
A, B, and C (Patient of legal age, legal representative, legal guardian)
36
What weighted image would be created with the following parameters: TR 500, TE 10, FA 90?
T1
37
What tissue is bright on diffusion-weighted imaging?
Abnormal tissue and tissue with low ADC
38
The time constant of the precessional frequency of a specific MR-active nucleus at 1 Tesla in MHz/T is called:
Gyromagnetic ratio
39
What determines the amount of ferromagnetic reaction/attraction?
All of the above (Size, shape, and material composition)
40
Whose law states that 'a moving electric current creates a magnetic field'?
Michael Faraday
41
What is the Tesla strength for the Larmor precessional frequency of 170.32 MHz?
4T
42
What is a pulse oximeter?
A device that measures blood oxygen levels
43
SE scan time formula is:
TR × Phase matrix × NSA
44
The point in a tissue’s longitudinal recovery where no magnetization remains and no signal is created on an IR pulse sequence is called:
Null point
45
T2-weighted, fluid-attenuated inversion recovery (FLAIR) sequences are typically used for the evaluation of:
Periventricular white matter disease such as multiple sclerosis
46
Which combination of TE and TR creates a PD-weighted image?
Short TE, long TR
47
Gradient echo sequences acquired for high signal from fluid are known as all of the following EXCEPT:
Incoherent gradient echoes
48
Calculate the scan time for a fast spin echo with the following parameters: FOV 20cm, TR 3000, TE 120, 224 × 256 matrix, 3 NEX, 5 mm slice thickness, 12 ETL.
2 min. 48 sec.
49
What can cause NSF?
Certain types of gadolinium contrast remaining in the human body too long
50
Phase is:
A position at a given time
51
What were the early NMR machines used to study, and what was the name of this technique?
Chemicals, spectroscopy
52
A person who is allergic to seafood will have an allergic reaction to IV gadolinium contrast.
False
53
What zone should screening be completed in?
Zone 3
54
The application of an RF pulse that causes resonance to occur is termed:
Excitation
55
One of the reasons that the hydrogen atom is used in clinical MR imaging is its abundance in the body and:
Its solitary proton creates a large magnetic moment
56
What is a typical TI time for T2 FLAIR?
1700-2200 ms
57
What is a 'quench'?
Sudden loss of liquid helium and magnetic field
58
In a dual-echo sequence for proton density and T2 weighting, which echo is the proton density?
TE 20ms
59
What is the term used to describe the rapid loss of superconductivity in an MRI magnet, resulting in the release of helium gas?
Quench
60
A condition where the TR is less than T1 and T2 relaxation times of tissues, where energy in equals energy out, is known as:
Steady state
61
What is the Ernst angle?
Flip angle that provides optimum signal intensity
62
What weighted image would be created with FSE, TR 6000, TE 100, ETL 16?
T2
63
Who was the first person to demonstrate a radio signal from the nucleus of an atom?
Isidor Rabi
64
Which of the following best describes an EPI sequence?
A “train” of gradient echoes
65
Gradient echo T1-weighted sequences use:
Gradient or RF spoiling
66
What is the most important safety consideration for a patient who has had a cardiac pacemaker removed?
That the pacer wires are still in the patient’s body
67
What is the first thing that should be done for a patient who is having a medical emergency during an MRI?
Remove the patient from the scanner, place them in zone 3, secure the MRI scan room door, and then call for help
68
TR 9000, TE 125, TI 2200, FM 256, PM 224, 10 ETL, slice thickness 5mm, 2mm gap would yield images with what weighting?
T2 FLAIR
69
What is the temperature of liquid helium?
4 K / -270 degrees C / -452 degrees F
70
What is the FDA-recommended amount of SAR for the head averaged over 10 minutes?
3 W/kg
71
In STIR sequences, which tissue is being suppressed?
Fat
72
What is a cochlear implant?
An implant in the inner ear
73
What conditions are necessary for resonance?
Energy applied at the precise frequency and at a right angle
74
An advantage of using gradient echo sequences is:
Faster scan times
75
Calculate the scan time for a fast spin echo sequence with the following parameters: FOV 16cm, TR 2500, TE 90, 224 x 256 matrix, 6 NEX, 5mm slice thickness, 18 ETL.
3.11 minutes
76
Calculate the scan time for a fast spin echo with the following parameters: TR 3500, TE 100, 256 x 256 matrix, 4 NEX, 5mm slice thickness, 14 ETL.
4 min. 16 sec.
77
Which statement is NOT true about FSE T2 pulse sequences?
Fat is darker than on SE pulse sequences
78
GRE with a small flip angle, long TR, short TE would yield:
PD weighted
79
In IR sequences, the resultant contrast depends primarily on the:
TI
80
All patients with joint replacements can safely undergo an MRI.
False
81
A patient with a spinal cord stimulator can never be scanned with MRI.
False
82
Spin echo sequences are useful for:
A, B, and C only (T1, T2, and PD weighted images)
83
Precessional frequency in MRI is measured in:
MHz
84
FSE/TSE sequences are useful for:
A, B, and C only (T1, T2, and PD weighted images)
85
Where can you find the latest information regarding MRI registry?
ARRT.org
86
A TI time of 150ms on a 1.5T magnet will null the signal from what tissue?
Fat
87
Arthrographic means:
Visualize joint spaces
88
What does GRASE stand for?
Gradient echo and spin echo
89
Which of the following is NOT one of the intrinsic contrast parameters?
TR
90
What is a transdermal patch?
A medication delivery device
91
When would a tattoo be considered MR unsafe?
If it has iron oxide inks
92
Myelographic means:
Spinal cord and nerve visualization
93
Calculate the scan time for a spin echo sequence with the following parameters: TR 500, TE 25, 224 x 256 matrix, 2 NSA, 3mm slice thickness.
3 min 44 sec
94
What is required if the MRI table is not detachable?
There must be an MRI-safe gurney readily available
95
Gradient echo sequences acquired for the evaluation of hemorrhagic lesions rely on:
Susceptibility
96
What is the precessional frequency for hydrogen on a 5T external static magnetic field?
212.9 MHz
97
What type of echoes are generated in EPI?
Gradient echoes
98
What extrinsic factor controls the amount of T1 recovery?
TR
99
If a quench has occurred, the operator should evacuate the room to avoid:
Asphyxiation and frostbite
100
Calculate the scan time for a 3D GRE echo sequence with the following parameters: TR 40, TE 24; FOV 30; 192 x 256 matrix; 1 NSA, F/A 45; 3.5 mm slice thickness; 31 slices.
3 min. 58 sec.
101
Imaging parameters in GRE T1-weighted sequences should have:
Large flip angle, short TR, short TE
102
What is the extrinsic contrast parameter unique to TSE/FSE?
Turbo factor or echo train length
103
What signal/s are sampled in coherent or rewind GE sequences?
The FID and the stimulated echo
104
What is the scan time for a proton density-weighted image assuming the following parameters: TR 3000ms, TE 20; 256 x 256, NSA 1, ETL 4?
3 minutes 12 seconds
105
The pulse sequence consisting of a variable flip angle RF excitation pulse followed by a pulse of the magnetic field gradients is called:
Gradient echo
106
What weighted image would be created with a CSE, TR 600, and TE 15?
T1
107
Where is a common place for a vascular filter?
IVC
108
Imaging parameters in GRE T2*-weighted sequences should have:
Small flip angle, long TR, long TE
109
A gradient echo sequence in which any residual transverse magnetization is removed prior to the next excitation pulse is known as:
Incoherent/spoiled
110
With regard to energy, protons in parallel alignment are in the _________ state, whereas protons in anti-parallel alignment are in the __________ state.
Low, high
111
STIR sequences can suppress the signal from all of the following EXCEPT:
Fluid (CSF)
112
The B1 magnetic field is produced by:
RF coil
113
The null point of a tissue in an IR pulse sequence is calculated by:
0.69 x the T1 relaxation time of a tissue
114
The following parameters are suitable in a T2 FLAIR sequence EXCEPT:
Short TE to enhance T2 weighting
115
What image would be created with the following parameters: TR 2000, TE 60, TI 150?
STIR
116
What zone should all persons be supervised?
Zones 3 and 4
117
Spins aligned in the anti-parallel direction are in __________.
A high energy state
118
What is the Larmor equation used to calculate?
Precessional frequency
119
A technique that uses the differences in magnetic susceptibility between oxyhemoglobin and deoxyhemoglobin to image areas of activated cerebral cortex is:
BOLD
120
A rapid acquisition technique that begins with a sequence of one or more RF pulses and is followed by a series of gradient echoes:
EPI
121
What is an 'active' implant?
An implanted device that has a power source other than the human body itself
122
Which of the following is not one of the extrinsic parameters?
Proton Density (PD)
123
Angiographic means:
Visualize blood vessels and flow
124
What is a Hahn echo?
Any two 90° RF pulses produce one
125
In what year did MRI receive its FDA approval?
1985
126
Short tau inversion recovery (STIR) images are:
T2-weighted, fat-nulled images
127
Who is responsible for verifying that all the custodial staff are educated and trained about MR safety?
All MR technologists on staff
128
Which combination of TR and TE create a T1-weighted image?
TE 30ms, TR 300ms
129
Why should a patient have their kidney function tested before an MRI is performed with IV gadolinium contrast injection?
To make sure the contrast will be filtered out from the body in a reasonable amount of time
130
What type of echoes are generated in EPI?
Gradient echoes
131
What extrinsic factor controls the amount of T1 recovery?
TR
132
If a quench has occurred, the operator should evacuate the room to avoid:
Asphyxiation and frostbite
133
Calculate the scan time for a 3D GRE echo sequence with the following parameters: TR 40, TE 24; FOV 30; 192 x 256 matrix; 1 NSA, FA 45; 3.5 mm slice thickness; 31 slices.
3 min. 58 sec.
134
Imaging parameters in GRE T1-weighted sequences should have:
Large flip angle, short TR, short TE
135
What is the extrinsic contrast parameter unique to TSE/FSE?
Turbo factor or echo train length
136
What signals are sampled in coherent or rewind GE sequences?
The FID and the stimulated echo
137
What is the scan time for a proton density weighted image assuming the following parameters: TR 3000ms, TE 20; 256 x 256, NSA 1, ETL 4?
3 minutes 12 seconds
138
The pulse sequence consisting of a variable flip angle RF excitation pulse followed by a pulse of the magnetic field gradients is called:
Gradient echo
139
What weighted image would be created with a CSE, TR 600, and TE 15?
T1
140
Where is a common place for a vascular filter?
IVC
141
Imaging parameters in GRE T2*-weighted sequences should have:
Small flip angle, long TR, long TE
142
A gradient echo sequence in which any residual transverse magnetization is removed prior to the next excitation pulse is known as:
Incoherent/spoiled
143
With regard to energy, protons in parallel alignment are in the _________ state, whereas protons in anti-parallel alignment are in the __________ state.
Low, high
144
What is the purpose of the initial RF pulse in a coherent gradient echo sequence?
Spin excitation
145
All surgical staples, clips, and metallic sutures are MR unsafe.
False
146
T2 relaxation time is defined as when:
63% of the transverse magnetization has decayed
147
What is the FDA recommended amount of SAR for the head averaged over 10 minutes?
3 W/kg
148
In STIR sequences, which tissue is being suppressed?
Fat
149
What is a cochlear implant?
An implant in the inner ear
150
What conditions are necessary for resonance?
Energy applied at the precise frequency and at a right angle
