Instrumentation

Question 1

magnetic fields associated with MR imaging system include the

Answer 1

static magnetic field

RF field

gradient field

Question 2

MR system component that produces the B(o) field is the

Answer 2

main magnet

Question 3

the MR system component that produces the B(1) field is the

Answer 3

radiofrequencey system

Question 4

there are various types of magnets that can be sued for MR imagers, these include

Answer 4

permanent magnet

resisteive

magnet

hybrid magnet

‘superconductive magnet

Question 5

the MR system component that provieds a meads for alignment of proton spins is the

Answer 5

main magnet

Question 6

the MR system component that provides a meands for excitation is the

Answer 6

radio frequency system

Question 7

the MR system component that provides a means for spatial encoding is the

Answer 7

gradient system

Question 8

the liquid cryogen commonly used to maintain the magnet coil at superconducting temperatures is

Answer 8

helium

nitrogen

Question 9

some systems use only one cryogen in such systems the cryogen is

Answer 9

helium

Question 10

faradays law of induction states that if a loop of wire is moved through a magnetic field____will be created in the wire

Answer 10

voltage

Question 11

the equation associated with faradays law of induction is

Answer 11

ΔB/ΔT=ΔV

Question 12

according to faradays law of induction the amount of current produced in a loop of wire moving through a magnetic field is proportional to the

Answer 12

strength of magnetic field

Question 13

in a typical superconducting cylindrical bore magnet, the direction of the magnetic field is

Answer 13

horizontal

Question 14

the direction of the magnetic field in a typical permanent magnet is

Answer 14

vertical

Question 15

to maintain the magnetic field of a resisteive magnet which of the follwoing should be applied to the magnet coils

Answer 15

current

Question 16

magnetic field strength is measured in units of Tesla (T) and Gauss (G) whereby 1 T equals

Answer 16

10000 G

Question 17

1.5 T =(gauss)

Answer 17

15000 G

Question 18

in a superconducitng magnet the magnetic field strength is increases by increasing the

Answer 18

turns of a wire

Question 19

in a solenoid supierconducint magnet the direction of current flow affects the

Answer 19

direction of magnetic field

Question 20

permanent magnets with a vertical magnetic field use surface coils taht are

Answer 20

solenoids

Question 21

the transmit bandwidth of the RF pulse affects

Answer 21

spatial resolution

\slice thickness

Question 22

in order to create a thin slice thickness a _______is used

Answer 22

steep slice selecting gradient

high amplitude slice select gradient

narrow transmit bandwidth

Question 23

the receiver bandwidth affects

Answer 23

chemical shift artifacts

SNR

Question 24

if a coil is improperly tuned it will result in

Answer 24

a decrease in SNR

Question 25

gradient magnetic fields are

Answer 25

always on

Question 26

the timing of RF pulses during an MR pulse sequence

Answer 26

controls image contrast

Question 27

the B1 magnetic field is produced by a

Answer 27

RF coil

Question 28

in an MRI system that uses shim coils the B(o) homogeniety is adjusted by

Answer 28

changing current in the shim coil

Question 29

shimming in MRi is performed by all of the followoing

Answer 29

changing current in the shim coil

adding metal to different coils within the shim coil

adding current to the gradient coils

Question 30

gradient strength (amplitude) is measured in units of

Answer 30

mT/M

G/cm

Question 31

gradient speed (rise time) is measure in units of

Answer 31

µs

Question 32

gradient speed and strength is measured in units of

Answer 32

T/m/s

Question 33

the amount of time that a gradient is permitted to work is known as the duty cycle and is measured in units of

Answer 33

%

Question 34

the gradient strength is measure in units of

Answer 34

amplitude

Question 35

the gradient characteristic that reflects both strength and speed is known as the

Answer 35

slew rate

Question 36

gradients can work for a period of time known as the

Answer 36

duty cycle

Question 37

gradient characteristics for speed is known as the

Answer 37

rise time

Question 38

RF coil configureations include

Answer 38

linear

quadrature

phase array

helmholtz

multichannel

Question 39

RF coil configureations that use multiple coils with one single receiver include

Answer 39

helmholtz

Question 40

RF coil configurations that use multiple coils with multiple receivers are

Answer 40

phase array

multichannel

Question 41

the sensitivy profile for a given coil is known as the

Answer 41

pulse profile

Question 42

RF coil configuration that use coils whereyby the coil is configured with wires or electronic components that are perpendicular to one another are known as

Answer 42

quadrature