Chapter 5

Question 1

Parallel imaging is usually used to increase resolution or decrease scan time. (T or F)

Answer 1

true

Question 2

What do T1 images typically best demonstrate?

Answer 2

Anatomy

Question 3

What does STIR stand for? Short ___ Inversion Recovery.

Answer 3

tau

Question 4

SSFP sequences usually produce images that are ___ weighted.

Answer 4

T2

Question 5

What are the advantages of propeller K Space filling?

Answer 5

Rapid imaging, increased SNR and CNR, reduced motion artifact.

Question 6

Which sequence is considered the gold standard for MR imaging

Answer 6

Spin Echo

Question 7

How is time reduced in fast spin echo?

Answer 7

Use a turbo factor, Use an echo train

Question 8

What is Double IR prep used to accomplish?

Answer 8

Used to null blood for cardiac imaging

Question 9

What type of echoes are sampled during SS-FSE?

Answer 9

Spin echoes

Question 10

What artifact can occur as a result of using long echo trains?

Answer 10

Image Blurring

Question 11

When would we be most likely to use a FLAIR sequence?

Answer 11

Head or spine studies (to look for periventricular lesions)

Question 12

Which Fast Inversion Recovery sequence(s) do we often use?

Answer 12

FLAIR, STIR

Question 13

What is the approximate T1 relaxation time of fat at 1T?

Answer 13

200 ms

Question 14

Which of the following statements is true in an incoherent gradient echo sequence?

Answer 14

The system discriminates between residual and the most recently created transverse magnetization because it has a different phase value

Question 15

look at q 16 (quiz)

Answer 15

_

Question 16

look at q 14 (quiz)

Answer 16

_

Question 17

How is K space filled in Fast Gradient Echo Sequences?

Answer 17

Keyhole filling,

Centric filling

Question 18

When would we be most likely to use a STIR sequence?

Answer 18

MSK studies (i.e. knee, wrist)

Question 19

Spin echo pulse sequences are classified according to whether the residual transverse magnetization is in phase (coherent) or out of phase (incoherent). (T or F)

Answer 19

False

GRADIENT ECHO sequences are classified according to whether the residual transverse magnetization is in phase (coherent) or out of phase (incoherent). See page 167 in the text for more information.

Question 20

What is the approximate T1 relaxation time of CSF at 1T?

Answer 20

2000 ms

Question 21

In which of the following sequences is all the transverse magnetization rewound at the end of each TR period?

Answer 21

Coherent gradient echo

Question 22

An inversion recovery pulse sequence begins with which of the following?

Answer 22

180 degree inverting pulse

Question 23

FLAIR stands for Fluid Low Attenuation Inversion Recovery

T or F

Answer 23

False

FLAIR stands for Fluid Attenuated Inversion Recovery

Question 24

STIR sequences should NOT be used in conjunction with contrast enhancement. (T or F)

Answer 24

True

STIR sequences should NOT be used in conjunction with contrast enhancement, which shortens the T1 times of enhancing tissues, making them bright. The T1 times of these structures are shortened so that they approach the T1 time of fat. In a STIR sequences therefore, enhancing tissue may also be nulled. See page 158 in the text for more information.

Question 25

During EPI all the lines of K space are filled during one repetition. (T or F)

Answer 25

true

Question 26

Using a long echo train decreases the SAR. (T or F)

Answer 26

False Using a long echo train significantly increases the SAR by applying so many successive 180 degree pulses. See page 150 in the text for more information.

Question 27

look at q 1, 2, 9, (study guide)

Answer 27

_

Question 28

what order is centric filling in K space

Answer 28

center lines first, outer last

Question 29

what order is keyhole filling in K space

Answer 29

outer first, center after contrast injection

Question 30

what order is EPI k space filling

Answer 30

readout gradient switches from pos to neg, phase polarity does not change

Question 31

what order is spiral k space filling

Answer 31

readout and phase both switch polarity

Question 32

Generally speaking, gradient echo sequences are faster than spin echo sequences. (T or F)

Answer 32

true

Question 33

Which pulse sequence is the gold standard?

Answer 33

spin echo

Question 34

What are the two fast inversion recovery sequences that we often use?

Answer 34

STIR. Nulls the signal from fat. | FLAIR. Nulls CSF.

Question 35

what are the uses of STIR

Answer 35

musculoskeletal

Question 36

what are uses for FLAIR

Answer 36

periventricluar lesions

Question 37

coherent gradient echo

Answer 37

rewinding. transverse is rewound at end of each TR

Question 38

incoherent gradient echo

Answer 38

spoilers. differentiates between residual and most recently created transverse magnetization

Question 39

which is True T2* - angiographic, myelographic or arthrographic effect

Answer 39

coherent gradient echo

Question 40

which demonstrate T1 anatomy and pathology and after gadolinium?

Answer 40

incoherent gradient echo

Question 41

During which k-space filling are lines filled as a block and rotated about the central axis of k-space, decreasing scan time, increasing the SNR and decreasing motion?

Answer 41

propeller

Question 42

Which of the following describes a "steady state" in MRI?

Answer 42

Created when the TR is shorter than the relaxation time of tissues. Energy "in" by the FA = energy "out" during the TR Residual builds in the transverse plane resultant image is a ratio of T1 to T2

Question 43

What is used to rephase the FID in gradient sequences?

Answer 43

a gradient

Question 44

Which type of imaging fills multiple lines of k-space per TR by assigning lines of k-space to coils coupled together, thus acquiring data simultaneously.

Answer 44

Parallel imaging. Can be used to reduce scan time or improve resolution.

Question 45

What does this statement describe? As the area of the gradient under the line equals that above the line, moving spins accumulate a zero change as they pass along the gradients.

Answer 45

balanced gradient system

Question 46

double IR prep

Answer 46

black blood

Question 47

triple IR prep

Answer 47

nulls fat and blood

Question 48

RF spoiling

Answer 48

only info from the most recently created magnetization to affect image contrast

Question 49

gradient spoiling

Answer 49

residual magnetization is dephase so it is incoherent at beginning of next repition

Question 50

advantage of spin echo

Answer 50

good quality, true T2

Question 51

disadvantage of spin echo

Answer 51

long scan times

Question 52

T1 most useful to

Answer 52

demonstrate anatomy

Question 53

T2 most useful to

Answer 53

demonstrate pathology

Question 54

effective TE

Answer 54

weighting in fast spin echo bc echoes are generated at different TE times

Question 55

T2*

Answer 55

always present to some degree

Question 56

True T2

Answer 56

steady state free precession (SSFP)

Question 57

Relaxation times of water

Answer 57

2500 ms (for T1 and T2 times)

Question 58

relaxation T1 time of fat

Answer 58

200 ms

Question 59

relaxation T2 time of fat

Answer 59

100

Question 60

relaxation T1 time of CSF

Answer 60

2000 ms

Question 61

relaxation T2 time of CSF

Answer 61

300 ms

Question 62

Which pulse sequence are classified according to whether the residual transverse magnetization is in-phase (coherent) or out-of-phase (incoherent)?

Answer 62

gradient

Question 63

___: Partial Fourier + fast spin echo. Half the lines are acquired and half are transposed. Reduces SAR but has SNR penalty.

Answer 63

single-shot fast spin echo