Week 3

Question 1

which pulse sequence retains residual transverse magnetization and provides strong T2 contrast?

Answer 1

steady state GRE

Question 2

what controls the steady state due to the short TR?

Answer 2

flip angle controls RF saturation

Question 3

which pulse sequence destroys residual transverse magnetization and provides strong T1 contrast?

Answer 3

spoiled steady state GRE

Question 4

When is spoiled steady state applied in the cycle?

Answer 4

at the end of each excitation cycle

Question 5

which pulse sequence rewinds residual transverse magnetization to maintain coherence in SE and FSE sequences?

Answer 5

rewound steady state

Question 6

When is a rewound steady state applied in the cycle? which direction?

Answer 6

at the end of each cycle

in the phase-encoding direction

Question 7

which pulse sequence removes residual transverse magnetization with longer TE and provides true T2 contrast?

Answer 7

reverse-echo GRE

Question 8

which pulse sequence uses gradient moment nulling to reduce flow artifacts, providing stable images in the presence of motion?

Answer 8

balanced GRE

Question 9

which pulse sequence achieves very fast imaging sequences, especially in SE w/ 180-degree refocusing pulses?

Answer 9

echo planar imaging

Question 10

which sequence use a 90-degree and 180-degree RF pulse sequence to refocus spins?

Answer 10

SE sequences

Question 11

which sequence rely on a lower flip angle and do not use a 180-degree refocusing pulse?

Answer 11

GRE sequences

Question 12

which sequence is more prone to inhomogeneity artifacts?

Answer 12

GRE sequences

Question 13

what do GRE sequences achieve that allows for quicker imaging?

Answer 13

shorter TRs

Question 14

which sequence has more contrast options?

Answer 14

SE sequences

Question 15

which direction is balanced GRE is applied?

Answer 15

in the frequency or slice-select direction

Question 16

what’s balanced GRE purpose?

Answer 16

realigns protons moving through the gradients w/ stationary protons

eliminating phase artifacts (ghosting)

Question 17

what gives us the residual transverse magnetization?

Answer 17

steady state

Question 18

what creates steady state? and how is it created?

Answer 18

Hahn echoes, by the continuous pulsing of RF energy

Question 19

what does it mean to have short TR and TE settings?

Answer 19

RF pulses happen quickly, doesn’t not allow time to fully relax

Question 20

True or False. Only Spin Echo Pulse Sequences can create this steady state, as they allow for fast pulsing required

Answer 20

False. only GRE

Question 21

Name 2 speed up echo formation

Answer 21

1. FSE
2. EPI (echo planar imaging)

Question 22

what technique is EPI?

Answer 22

single-shot

Question 23

what’s the main component of an EPI?

Answer 23

how we fill k-space, NOT echo formation

Question 24

Does EPI fill the entire slice of k-space in 1 TR period?

Answer 24

yes

Question 25

what are the 3 studies EPI used for?

Answer 25

1. diffusion 2. perfusion 3. functional MRI

Question 26

what can EPI possibly cause for pt?

Answer 26

PNS

Question 27

True or False. EPI is not prone to susceptibility artifacts and geometric distortions

Answer 27

False

Question 28

what's the goal of IR?

Answer 28

eliminate/ suppress the signal from a given tissue

Question 29

Name 2 main IR sequences

Answer 29

1. STIR 2. FLAIR

Question 30

how is IR accomplished?

Answer 30

by choosing the ideal timing between an initial RF inversion pulse and an RF excitation pulse

Question 31

what is the time between the inversion pulse and the excitation pulse?

Answer 31

inversion time (TI)

Question 32

what is TI based on?

Answer 32

given tissue's T1 relaxation time

Question 33

which IR sequence has shorter TI?

Answer 33

STIR

Question 34

which IR sequence has longer TI?

Answer 34

FLAIR

Question 35

what tissue does STIR suppress?

Answer 35

fat

Question 36

what tissue does FLAIR suppress?

Answer 36

water/ CSF

Question 37

what is the non-cartesian filling that doesn't add additional time?

Answer 37

keyhole faster scan time = higher temporal reso

Question 38

what does a lower FA in GRE do?

Answer 38

allows T2* weighting eliminate T1 weighting longest TE possible

Question 39

what does a higher FA in GRE do?

Answer 39

allows T1 weighting shortest TE possible

Question 40

what is Hahn echo created out of?

Answer 40

out of phase w/ new FID

Question 41

how do I allow the full longitudinal to recover?

Answer 41

don’t flip the NMV as far (gives it a head start) lower flip angle

Question 42

what do I do to eliminate T1 waiting?

Answer 42

lower flip angle

Question 43

what does having a long TR do for us in Spin Echo Sequence?

Answer 43

allow longitudinal to recover fully trade-off = lower T1 contrast

Question 44

how to get T1 in GRE?

Answer 44

high flip angle short TE (0-5)

Question 45

how to get T2 in GRE?

Answer 45

low flip angle long TE (15-30)

Question 46

how to get T2* in GRE?

Answer 46

low flip angle (5-25) long TE (15-30)

Question 47

how to get PD in GRE?

Answer 47

low flip angle (5-25) short TE (0-5)

Question 48

what are the 2 signals created at each RF pulse?

Answer 48

1. FID 2. Hahn echo

Question 49

what does FIESTA stand for?

Answer 49

Fully Balanced Steady State

Question 50

where is FIESTA applied in the cycle?

Answer 50

in the slice select in the frequency encoding direction

Question 51

which is the 3rd chemical suppression technique?

Answer 51

Dixon

Question 52

what does Dixon technique use to suppress fat or water?

Answer 52

math based on in and out of phase echo collections

Question 53

what is this equation used to suppress? 1/2 IP + OP

Answer 53

fat suppressed (water only images)

Question 54

what is this equation used to suppress? 1/2 IP - OP

Answer 54

water suppressed (fat only images)