Fundamentals

Question 1

in the equation associated with LARMOR Equation, B(o)stand for

Answer 1

static magnetic field

Question 2

in the equation associate with Larmor Equation, ω(o) stand for

Answer 2

frequency

Question 3

in the equation associate with Larmor Equation, ϒ stand for

Answer 3

gyromagnetic ratio

Question 4

a magnetic field strength of .05 T is equivalent to

Answer 4

5000 G

Question 5

a condition whereby there are MORE spins in line with the magnetic field that opposed is knwn as

Answer 5

theralequilibrium

Question 6

during thermal equalibrium there are

Answer 6

more spins in the low energy state

Question 7

proton spins that are in line with the static magnetic field B(o) are referred to as all of the following

Answer 7

spin up

parallel

low energy spins

Question 8

the microscopic magnetic field associated with the proton within the magnetic field is knwn as the

Answer 8

magnetic moment (µ)

Question 9

during thermal equilibrium the vector taht represents the spn excess is known as the

Answer 9

net magnetization value (NMV)

Question 10

the RF pulse is applied to acheive a condition known as

Answer 10

excitation

Question 11

during excitation all of the following occur

Answer 11

low energy spins enter high energy state

spins begin to precess in phase

the NMV is transferred into the transverse plane

Question 12

During relaxation all of the folloiwng occur

Answer 12

high energy spins return to a low energy state

spins begin to precess out of pahse or lose phase coherence

the NMV recovers longitudinally

Question 13

T1 relaxation is also known as all of the following

Answer 13

T1 recovery

spin lattice

longitudinal recovery or relaxatoin

Question 14

T2 relaxatoin is also known as

Answer 14

spin spin

Question 15

T2 relaxatoin is also known as all of the following

Answer 15

T2 decay

spin spin

transverse relaxation

Question 16

T1 relaxation time is defined as when

Answer 16

63% of the longitudinal magnetization has regrown

Question 17

T2 relaxatoin time is defined as when

Answer 17

63% of the transverse magnetization has decayed

Question 18

images acquired with a spin echo pulse sequence having a SHORT TR and TE valuse yield images known as

Answer 18

T1WI

Question 19

images acquired with a spn echo pulse sequence having a LONG TR and TE valuses yield images known as

Answer 19

T2WI

Question 20

images acquired with a spin echo pulse sequence having a LONG TR and SHORT TE valuse syield images known as

Answer 20

PDWI

Question 21

spino density is another term for

Answer 21

proton density

Question 22

spin density is determined by the

Answer 22

amount of excess spins in the low energy state at equilibrium

Question 23

gradient echo (steady state) sequences acquired with short TR and flip angle combinations along with a moderately long TE yield images with

Answer 23

T2* contrast

Question 24

T2 + T2’ equals

Answer 24

T2*

Question 25

the LOGICAL gradient that is used for slice selection for the acquisition of an axial slice is the

Answer 25

z gradient

Question 26

the PHSYICAL gradient that is used for slice selection for the acquisition of an aial slice is the

Answer 26

z gradient

Question 27

the LOGICAL gradient that is used for slice selection for the acquisition of a sagittal slice is the

Answer 27

z gradient

Question 28

the PHYSICAL gradient that is used for slice selection for the acquisition of a sagittal slice is the

Answer 28

x gradient

Question 29

the LOGICAL gradient that is used for phsae encoding for the acquisition of an axial slice of the abdomen is the

Answer 29

y gradient

Question 30

the LOGICAL gradient that is used for phase encoding for the acquisition of an axial slice of the head is the

Answer 30

y gradient

Question 31

the PHYSICAL gradient that is used for phase encoding for the acquisition of an axial slice of the abdomen is the

Answer 31

y gradient

Question 32

the PHYSICAL gradient taht is used for phase encoding for the acquisition of an axial slice of the head is the

Answer 32

x gradient

Question 33

the receiver bandwidth is related to the slope of the

Answer 33

frequency encoding gradient

Question 34

following a 90 RF pulse the signal that is created is called

Answer 34

free induction decay

Question 35

T2* is a result of dephasing due to tissues T2 time and

Answer 35

susceptibility

inhomogeneities

chemical shift

Question 36

the peak signal strength of a spin echo is less than the initial signal strength of the free induction decay because of

Answer 36

T2 relaxation

Question 37

an example of a dipole is

Answer 37

hydrogen nucleus

bar magnet

earth

Question 38

a vector has both direction and

Answer 38

magnatude

Question 39

hydrogen nuclei have a magnetic moment because they possess a property called

Answer 39

spin

Question 40

when placed in a large static magnetic field hygdrogen nuclei

Answer 40

align in either a parallel or anitparallel position

Question 41

spins aligned in the antiparallel directino are in

Answer 41

high energy state

Question 42

during thermal equilibrium the spin excesses of individual hydrogen nuclei add to form

Answer 42

a net magnetization vector

NMV

Question 43

the formula that describes the relationship between the static magnetic field and the precessional frequency bo the hydrogen protons is the

Answer 43

larmor equation

Question 44

o calculate the precessional frequencey the strength of the static magnetic field is multiplied by a constan knows as the

Answer 44

gyromagnetic ratio

Question 45

the condition reached with a few seconds of hydrogen being placed in a magnetic field is described as

Answer 45

thermal equilibrium

Question 46

during thermal equilibrium the individual protons precess

Answer 46

out of phase

Question 47

in order for energy to transfer between systems the two systems must be at the same

Answer 47

resonant frequency

Question 48

assuming a TR sufficient for full recovery of longitudinal magnetization maximum signal is produced in the receiver coil when the net magnetization is tipped

Answer 48

90 deg

Question 49

in relatoin to the static magnetic field the RF field is oriented

Answer 49

perpendicular

Question 50

the RF energy used in MRI is classified as

Answer 50

electromagnetic radiation

Question 51

immediatly on the application of the 90 pulse the precessing protons

Answer 51

begin to precess in phase

Question 52

the MR signal is produced by magnetization

Answer 52

in the transverse plane

Question 53

frequency can be defined by the

Answer 53

rate of phase change per unit time

Question 54

gradient magnetic fields are used to

Answer 54

spatially encode the data

Question 55

slice thickness is controlled by

Answer 55

slope of the gradient

Question 56

the physcial graient along with the bore of the superconducting magnet is the

Answer 56

z gradient

Question 57

to produce a sagittal slice the physical gradient used during the excitation pulse is the

Answer 57

x gradient

Question 58

the gyromagnetic ratio for hydrogen is

Answer 58

42.6 MHz/T

Question 59

in a 0.5 T imager the precessional frequency of hydrogen is approximately

Answer 59

21.3 MHz

Question 60

the amount of RF energy necessary to produce a 45ͦͦ° flip angle is determined by the

Answer 60

coil being used

ampl;itude and duratin of the RF pulse

strength of the external magnetic field

Question 61

the gradient that varies in amplitude wtih each TR is the

Answer 61

phase encoding gradient

Question 62

the gradient that is on during the sampling of the echo is the

Answer 62

frequency encoding gradient

Question 63

K-space is

Answer 63

the raw data from which an MR image is created

Question 64

multiple coil elements combined with multiple receive channels is a

Answer 64

phased array coil