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MRI exam > Fundamentals > Flashcards

Fundamentals Flashcards

1
Q

in the equation for the Larmor equation B0 stands for
A) static MF
B) frequency
C) gyromagnetic ratio
D) voltage

A

a

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2
Q

In the larmor equation W0 stand for
A) static MF
B) frequency
C) gyromagnetic ratio
D) voltage

A

b

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3
Q

In the Larmor equation y stand for
A) static MF
B) frequency
C) gyromagnetic ratio
D) voltage

A

c

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4
Q

MF strength of 0.5T is =
A) 15 000 G
B) 5000 G
C) 1G
D) 10 000G

A

B

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5
Q

a condition where more spins are in line with the magnetic field than opposed is known as
A) low energy
B) high energy
C) thermal equilibrium
D) excitation

A

c

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6
Q

during thermal equilibrium there are
A) more spins in the low energy state
B) more spins in the high energy state
C) equal number of spins in both states
D) less spins in the low energy state

A

a

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7
Q

proton spins that are in line with B0 are referred to all of as the following except
A) spin up
B) parallel
C) low E
D) high energy

A

d

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8
Q

the microscopic MF associated with the proton within the MF is known as the
A) FID
B) magnetic moment
C) signal echo
D) FOV

A

b

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9
Q

in the low energy state protons are

A

spin up or parallel

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10
Q

in the high energy state protons are

A

spin down or antiparallel

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11
Q

during thermal equilibrium, the vector that represents the spin excess is known as the
A) FID
B) net magnetisation vector
C) signal echo
D) FOV

A

b

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12
Q

the RF pulse is applied to achieve a condition known as
A) thermal equilibrium
B) excitation
C) relaxation
D) scan timing

A

b

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13
Q

during excitation, all of the following occur EXCEPT
A) low E spins enter the high E state
B) spins begin to precess in phase
C) NMV is transferred into the transverse (XY) plane
D) high energy spins return to the low energy state

A

d

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14
Q

during relaxation all of the following occur except
A) low E spins enter high E state
B) high E spins return to low E state
C) spins begin to precess out of phase
D) NMV recovers longitudinally

A

a

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15
Q

T1 relaxation is known as all of the following except
A) T1 recovery
B) Spin lattice
C) longitudinal recovery
D) spin- spin

A

d

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16
Q

T2 relaxation is also known as
A) T1 recovery
B) spin lattice
C) longitudinal recovery
D) spin spin

A

d

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17
Q

T2 relaxation is known as all of the following except
A) T2 decay
B) spin lattice
C) spin spin
D) transverse relaxation

A

b

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18
Q

T1 relaxation is defined as when
A) 76% of the longitudinal mag has regrown
B) 63% of the longitudinal has regrown
C) 63% of the transverse has regrown
D) 76 % of the tissues mag has regrown

A

b

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19
Q

T2 relaxation is defined as when
A) 76% of the longitudinal mag has regrown
B) 63% of the longitudinal has regrown
C) 63% of the transverse has regrown
D) 76 % of the tissues mag has regrown

A

c

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20
Q

images acquired with a SE pulse sequence having a short TR and TE yields images known as
A) T1
B) T2
C) PD
D) DWI

A

a

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21
Q

images acquired with a spin echo pulse sequence having a log TR and long TE will yield
A) T1
B) T2
C) PD
D) DWI

A

b

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22
Q

images acquired with a spin echo pulse sequence with a long TR and short TE will yield
A) T1
B) T2
C) PD
D) DWI

A

c

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23
Q

spin density is another term for
A) nuclear density
B) spin density
C) proton density
D) b and c

A

c

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24
Q

spin density is determined by the
A) amount of excess spins in the low E state at equilibrium
B) Amount of transverse magnetisation at the time the echo is sampled
C) T1/T2
D) amount of excess spins in the high E state at equilibrium

A

a

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25
Q

GE steady state sequences acquired with a short TR and flip angle along with a moderately long TE will yield images of
A) T1
B) T2
C) PD
D) T2*

A

d

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26
Q

T2 + T2* =
A) T1
B) T2
C) PD
D) T2*

A

d

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27
Q

the logical gradient used for slice selection of an axial slice is
A) x
B) y
C) z
D) a combination

A

c

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28
Q

the physical gradient used for slice selection of an axial slice is
A) x
B) y
C) z
D) a combination

A

c

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29
Q

the logical gradient used for a sagittal slice is the
A) x
B) y
C) z
D) a combination

A

c

30
Q

the physical gradient used for slice selection of a sagittal slice is
A) x
B) y
C) z
D) a combination

A

a

31
Q

the logical gradient used for phase encoding for acquisition of an axial slice in the abdomen is
A) x
B) y
C) z
D) a combination

A

b

32
Q

the logical gradient used for phase encoding for the acquisition of an axial slice of the head is
A) x
B) y
C) z
D) a combination

A

b

33
Q

the physical gradient that is used for phase encoding for an axial slice of the abdomen
A) x
B) y
C) z
D) a combination

A

b

34
Q

the physical gradient used for phase encoding for an axial slice of the head is
A) x
B) y
C) z
D) a combination

A

a

35
Q

what are the physical gradients

A

this is the term related to the physical gradient of the body and the imaging plane required as the person lays in the scanner

36
Q

what is a logical gradient

A

this is the gradient as illustrated by a pulse sequence diagram

37
Q

what does z represent

A

slice selection gradient

38
Q

what does y represent

A

gradient encoding direction

39
Q

what does x represent

A

readout or frequency encoding direction

40
Q

the receiver BW is related to the slope of which gradient
A) frequency encoding
B) phase encoding
C) slice selection
D) transmitting gradient

A

a

41
Q

following the 90˚ RF pulse, the signal that is created is the
A) spin echo
B) gradient echo
C) FID
D) FRE

A

c

42
Q

T2* is a result of dephasing due to a tissue’s T2 time and
A) T1
B) susceptibility, inhomogeneity and chemical shift
C) molecular weight
D) a and b

A

b

43
Q

the peak signal strength of a spin echo is less than the initial signal strength of the FID because
A) T1 relaxation
B) T2* decay
C) spin density changes
D) T2 relaxation

A

d

44
Q

an example of a dipole is
A) a hydrogen atom
B) a bar magnet
C) the earths MF
D) a, b, c

A

d

45
Q

a vector has both direction and
A) purpose
B) current
C) magnitude
D) a fractional equivalent force

A

c

46
Q

hydrogen nuclei have a magnetic moment because they possess a property called
A) inversion
B) flux
C) spin
D) resonance

A

c

47
Q

when placed in a large magnetic field, hydrogen nuclei
A) align with the MF
B) alight either in a parallel or an antiparallel direction
C) oscillate
D) relax

A

b

48
Q

spins aligned in the antiparallel direction are in
A) an expanded energy state
B) a resonant condition
C) high energy state
D) a constant state of flux

A

c

49
Q

during thermal equilibrium, the spin excess of individual hydrogen nuclei add to form
A) a rotating vector
B) an oscillating vector
C) a varying vector
D) a ner magnetisation vector

A

d

50
Q

the formula that describes the relationship between the static MF and the precessional ƒ of the hydrogen protons is the
A) helmholtz relationship
B) Nyquist theorem
C) Larmor equation
D) Bloch equation

A

c

51
Q

To calculate the precessional ƒ, the strength of the magnetic field is multiplied by a constant known as the
A) gyromagnetic ratio
B) Tau
C) Alpha- 1
D) Linear attenuation coefficient

A

a

52
Q

the condition reached within a few seconds of hydrogen being placed in a magnetic field is known as
A) resonance
B) FID
C) phase coherence
D) thermal equilibirum

A

d

53
Q

during thermal equilibrium, the individual protons precess
A) at the same ƒ
B) in phase
C) out of phase
D) slower

A

c. this is because of inhomogeneities in the main MF and as a result of spin interactions

54
Q

in order for energy to transfer between systems, the two systems must be at the same
A) phase location
B) energy level
C) mass
D) resonant ƒ

A

d

55
Q

assuming a TR is sufficient for full recovery of longitudinal magnetisation, maximum signal is produced in the receiver coil when the NET magnetisation is tipped
A) 180˚
B) 90˚
C) away from the z axis
D) through the transverse plane

A

b. the receiver coil is orientated 90˚ t the physical z axis

56
Q

in relation to the B0 the RF is located
A) parallel
B) perpendicular
C) at 180˚
D) at 45˚

A

b

57
Q

the RF energy in MRI is classified as
A) electromagnetic radiation
B) ionizing radiation
C) nonradiation energy
D) investigational

A

a

58
Q

immediately on the application on the 90˚ the precessing protons
A) all flip into the high E state
B) tip into the transverse plane
C) begin to precess in phase
D) a and b

A

c

59
Q

the MRI signal is produced by magnetisation
A) out of phase
B) in the longitudinal direction
C) decayed
D) in the transverse plane

A

d. when the NMV passes through the receiver coil it induces signal in the coil

60
Q

ƒ can be defined as
A) rate of phase per unit time
B) phase/2
C) fourier equation
D) amplitude of signal

A

a

61
Q

gradient magnetic fields are used to
A) improve SNR
B) spatially encode the data
C) transmit the RF pulse
D) control the image contrast

A

b

62
Q

slice thickness is controlled by
A) length of gradient field
B) slope of gradient
C) receiver bandwidth
D) a and b

A

b. thinner slices are produced with higher amplitude gradients

63
Q

the physical gradient along the bore of a superconducting magnet is the
A) x
B) x, y
C) y
D) z

A

d

64
Q

to produce a sagittal slice, the physical gradient used during excitation is the
A) z
B) y
C) x
D) a and b

A

c

65
Q

the gyromagnetic ratio for H is
A) 63.86 MHz/T
B) 42.6 MHz/T
C) 1 G/cm
D)4 W/Kg

A

b

66
Q

on a 0.5T imager, the precessional ƒ of hydrogen is approx
A) 63.86 MHz
B) 42.6 MHz
C) 21.3 MHz
D) 0.5 MHz

A

c

67
Q

the amount of RF energy necessary to produce a 45˚ flip angle is determined by the
A) coil used
B) amplitude and duration of the RF pulse
C) strength of the external MF
D) all of the above

A

d. a smaller coil will need less RF, the longer and greater amplitude will increase flip angle, increasing the external field will increase the amount of power needed for the flip

68
Q

the gradient that varies in amplitude with each TR is the
A) phase encoding gradient
B) frequency encoding gradient
C) slice select gradient
D) a and b

A

a

69
Q

the gradient that is on during the sampling of the echo is the
A) phase encoding gradient
B) frequency encoding gradient
C) slice selection gradient
D) a and b

A

b. the readout gradient

70
Q

k-space is
A) the image in its natural state
B) A negative of an MRI image
C) the raw data from which the MR image is created
D) what comes after j space

A

c

71
Q

mutitple coil elements combined with multiple receivers
A) quadrature coil
B) surface coil
C) linear coil
D) phased array coil

A

d

MRI exam (14 decks)

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