Deck 42: Magnetic Resonance Imaging

Question 1

The quantity of resonating spins in a tissue expressed as a percentage of the proton density of water is

A)spin density ( $\rho$ ).
B)repetition time (TR).
C)echo time (TE).
D)inversion time (TI).

Answer 1

spin density ( $\rho$ ).

Question 2

The time between a 180-degree pulse and a 90-degree inversion pulse in an inversion recovery pulse system is

A)spin density ( $\rho$ ).
B)repetition time (TR).
C)echo time (TE).
D)inversion time (TI).

Answer 2

inversion time (TI).

Question 3

When gradient coils are referred to, the y axis coil is referred to as the ____ gradient.

A)selection
B)phase encoding
C)frequency encoding
D)none of the above

Answer 3

phase encoding

Question 4

When gradient coils are referred to, the z axis coil is referred to as the ____ gradient.

A)selection
B)phase encoding
C)frequency encoding
D)none of the above

Question 5

The source of magnetic fields within the body

A)is the spinning nucleus of an atom.
B)are the neutrons.
C)are the stationary electrons.
D)all of the above

Question 6

The Larmor frequency is the ____ frequency.

A)quantum
B)precessional
C)linear
D)all of the above

Question 7

The time between a 90-degree pulse and the echo during a spin-echo pulse sequence is

A)spin density ( $\rho$ ).
B)repetition time (TR).
C)echo time (TE).
D)inversion time (TI).

Question 8

The time required after precessing spins have aligned at an angle to the external field due to an RF pulse losing 63% of their coherence is

A)spin density ( $\rho$ ).
B)spin-spin relaxation time (T₂).
C)echo time (TE).
D)spin-lattice relaxation time (T₁).

Question 9

The time required for precessing spins to align with the constant external field to 63% of the maximum possible strength is

A)spin density ( $\rho$ ).
B)repetition time (TR).
C)echo time (TE).
D)spin-lattice relaxation time (T₁).

Question 10

The rotation of the axis of rotation is termed

A)precession.
B)rerotation.
C)nuclear orientation.
D)frequency.

Question 11

The gyromagnetic ratio is the ratio of the magnetic

A)moment to the moment of magnetic force.
B)force to the moment of inertia.
C)moment to the moment of inertia.
D)none of the above

Question 12

When gradient coils are referred to, the x axis coil is referred to as the ____ gradient.

A)selection
B)phase encoding
C)frequency encoding
D)none of the above

Question 13

Each of the following is an example of an RF pulse sequence EXCEPT

A)stationary.
B)spin-echo.
C)gradient.
D)inversion recovery.

Question 14

The gradient coils determine the

A)section thickness.
B)resolution.
C)plane of the image.
D)all of the above

Question 15

Protons will alternate from

A)parallel to antiparallel.
B)parallel to neutral.
C)perpendicular to positive.
D)positive to negative.

Question 16

The primary variable in the data collection procedure during MRI is the

A)repeats.
B)stationary magnet.
C)sequence of RF pulses.
D)all of the above

Question 17

The time interval between pulse sequences is

A)spin density ( $\rho$ ).
B)repetition time (TR).
C)echo time (TE).
D)inversion time (TI).

Question 18

The actual response of proton spin to an RF pulse is to

A)change the magnetic moment in a recovery circular motion.
B)change the magnetic moment in a precessing corkscrew motion.
C)remain stationary.
D)change the magnetic moment in a precessing circular motion.

Question 19

To produce magnetic field gradients in MRI, electromagnetic coils are oriented in

A)one dimension.
B)two dimensions.
C)three dimensions.
D)four dimensions.

Question 20

The MHz frequency magnetic field for MRI is produced by a/an

A)radio transmitter coil.
B)optical cable.
C)digital converter.
D)none of the above

Question 21

The basic principle of MR physics involves an established relationship between an external magnetic field and the gyromagnetic ratio of an atom.This is expressed as the

A)inverse square law.
B)Larmor equation.
C)Hounsfield coefficient.
D)H & D curve.

Question 22

Before performing an MR scan on a patient with compromised renal function,

A)the patient should be NPO for 24 hours.
B)the patient's GFR should be assessed.
C)an IVU should be performed.
D)an ultrasound study of the kidneys should be done.

Question 23

MRI has been achieved with ____ magnets.

A)resistive
B)permanent
C)superconductive
D)all of the above

Question 24

The strength of a MR signal is

A)directly proportional to the strength of the magnetic filed.
B)directly proportional to the strength of B_O.
C)directly related to the tesla of the magnet.
D)all of the above

Question 25

In order to create a more homogenous magnetic field in MR, ______ is required.

A)a radio frequency
B)a k-space coil
C)an autotransformer
D)shimming

Question 26

The characteristic MR noise that is uncomfortable for patients and staff is due the ________ turning on and off at a high frequency.

A)external magnet
B)external coils
C)gradient coils
D)RF coil

Question 27

To prevent extraneous RF signals from degrading MR image quality, MR scan suites are enclosed in a

A)copper cage.
B)steel cage.
C)Faraday cage.
D)both a and c

Question 28

In a MR gantry, the patient lies at

A)the lowest gantry level.
B)isocenter.
C)geometric center.
D)the center of the external coils.

Question 29

The most widely used technique for MR image reconstruction is

A)back projection.
B)interpolation.
C)fast Fourier transformation (FFT).
D)Larmor equation precession (LEP).

Question 30

The RF signal strength determines

A)brightness.
B)field strength.
C)section thickness.
D)spatial resolution.

Question 31

If a piece of equipment, object, or device is to be used for a MR procedure, it is important to

A)check its labeling by the ASTM Standard F2503.
B)check it first with a small personal magnet before using it in the scan room.
C)contact the MR vendor to check compatibility with the scanner.
D)bring it into the scan room prior to the patient's entry, to check its safety.

Question 32

Higher field strength MRI magnets permit

A)shorter scan times.
B)better resolution.
C)stronger signal strength.
D)all of the above

Question 33

The size of the tissue voxel determines

A)brightness.
B)field strength.
C)section thickness.
D)spatial resolution.

Question 34

The most common variable in operating an MRI unit is the ____ used to enhance image quality.

A)TI
B)TE
C)TR
D)all of the above

Question 35

In MRI, the primary visual factor is often called

A)linearity.
B)geometric shape.
C)resolution.
D)brightness.

Question 36

Contrast-enhanced MR images use ________as the contrast material of choice.

A)iodine
B)barium
C)gadolinium
D)hydrogen

Question 37

Which can serve as both the transmitter and receiver of the MRI signal?

A)the stationary magnet
B)the gradient coils
C)the RF coils
D)the cryogen coils

Question 38

Superconductive magnets used in MR are characterized by

A)field strengths of .2T-.35T.
B)the use of liquid helium as a cryogen.
C)resistive magnets with vertical fields.
D)the ability to turn the magnetic field on and off at will.

Question 39

The combination of field of view (FoV), acquisition matrix, and slice thickness determines the MR data element known as a

A)pixel.
B)voxel.
C)byte.
D)magnetic moment.

Question 40

Patient precautions with MR scanning include

A)claustrophobia.
B)not touching the inside of the gantry during scanning.
C)ferromagnetic implants or prosthetic devices.
D)all of the above

Question 41

Match the following choices with the correct statement as each relates to magnetic resonance imaging.
determines the plane of acquisition

A)Tesla
B)active shimming
C)resistive magnet
D)SE pulse sequence
E)gyromagnetic ratio
F)Faraday cage
G)voxel
H)cryogen
I)Larmor frequency
J)gradient coils
K)TE
L)precession
M)T₂ relaxation
N)GBCA
O)B₀
P)NSF

Question 42

Match the following choices with the correct statement as each relates to magnetic resonance imaging.
low in field strength and requires electricity to create the field

A)Tesla
B)active shimming
C)resistive magnet
D)SE pulse sequence
E)gyromagnetic ratio
F)Faraday cage
G)voxel
H)cryogen
I)Larmor frequency
J)gradient coils
K)TE
L)precession
M)T₂ relaxation
N)GBCA
O)B₀
P)NSF

Question 43

Match the following choices with the correct statement as each relates to magnetic resonance imaging.
a rotation of the axis of rotation

A)Tesla
B)active shimming
C)resistive magnet
D)SE pulse sequence
E)gyromagnetic ratio
F)Faraday cage
G)voxel
H)cryogen
I)Larmor frequency
J)gradient coils
K)TE
L)precession
M)T₂ relaxation
N)GBCA
O)B₀
P)NSF

Question 44

Match the following choices with the correct statement as each relates to magnetic resonance imaging.
spin-spin interaction

A)Tesla
B)active shimming
C)resistive magnet
D)SE pulse sequence
E)gyromagnetic ratio
F)Faraday cage
G)voxel
H)cryogen
I)Larmor frequency
J)gradient coils
K)TE
L)precession
M)T₂ relaxation
N)GBCA
O)B₀
P)NSF

Question 45

Match the following choices with the correct statement as each relates to magnetic resonance imaging.
a rare complication from gadolinium use, in patients with impaired renal function

A)Tesla
B)active shimming
C)resistive magnet
D)SE pulse sequence
E)gyromagnetic ratio
F)Faraday cage
G)voxel
H)cryogen
I)Larmor frequency
J)gradient coils
K)TE
L)precession
M)T₂ relaxation
N)GBCA
O)B₀
P)NSF

Question 46

Match the following choices with the correct statement as each relates to magnetic resonance imaging.
unit of magnetic field strength

A)Tesla
B)active shimming
C)resistive magnet
D)SE pulse sequence
E)gyromagnetic ratio
F)Faraday cage
G)voxel
H)cryogen
I)Larmor frequency
J)gradient coils
K)TE
L)precession
M)T₂ relaxation
N)GBCA
O)B₀
P)NSF

Question 47

Match the following choices with the correct statement as each relates to magnetic resonance imaging.
unique value for each element, measured in MHz/T

A)Tesla
B)active shimming
C)resistive magnet
D)SE pulse sequence
E)gyromagnetic ratio
F)Faraday cage
G)voxel
H)cryogen
I)Larmor frequency
J)gradient coils
K)TE
L)precession
M)T₂ relaxation
N)GBCA
O)B₀
P)NSF

Question 48

Match the following choices with the correct statement as each relates to magnetic resonance imaging.
begins with a 90° RF pulse and is followed by a 180° RF pulse

A)Tesla
B)active shimming
C)resistive magnet
D)SE pulse sequence
E)gyromagnetic ratio
F)Faraday cage
G)voxel
H)cryogen
I)Larmor frequency
J)gradient coils
K)TE
L)precession
M)T₂ relaxation
N)GBCA
O)B₀
P)NSF

Question 49

Match the following choices with the correct statement as each relates to magnetic resonance imaging.
same as precessional frequency

A)Tesla
B)active shimming
C)resistive magnet
D)SE pulse sequence
E)gyromagnetic ratio
F)Faraday cage
G)voxel
H)cryogen
I)Larmor frequency
J)gradient coils
K)TE
L)precession
M)T₂ relaxation
N)GBCA
O)B₀
P)NSF

Question 50

Match the following choices with the correct statement as each relates to magnetic resonance imaging.
a three-dimensional element of the digital image

A)Tesla
B)active shimming
C)resistive magnet
D)SE pulse sequence
E)gyromagnetic ratio
F)Faraday cage
G)voxel
H)cryogen
I)Larmor frequency
J)gradient coils
K)TE
L)precession
M)T₂ relaxation
N)GBCA
O)B₀
P)NSF

Question 51

Match the following choices with the correct statement as each relates to magnetic resonance imaging.
external, static magnetic field

A)Tesla
B)active shimming
C)resistive magnet
D)SE pulse sequence
E)gyromagnetic ratio
F)Faraday cage
G)voxel
H)cryogen
I)Larmor frequency
J)gradient coils
K)TE
L)precession
M)T₂ relaxation
N)GBCA
O)B₀
P)NSF

Question 52

Match the following choices with the correct statement as each relates to magnetic resonance imaging.
uses RF coils to create a homogeneous field

A)Tesla
B)active shimming
C)resistive magnet
D)SE pulse sequence
E)gyromagnetic ratio
F)Faraday cage
G)voxel
H)cryogen
I)Larmor frequency
J)gradient coils
K)TE
L)precession
M)T₂ relaxation
N)GBCA
O)B₀
P)NSF