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Flashcards in EXAM 2 Deck (42)
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1
Q

a: fast spin echo or turbo spin echo imaging.

A

a: fast spin echo or turbo spin echo imaging.

a spin echo imaging method in which several 180° refocusing are used in each TR period

2
Q

b. short TI inversion recovery (STIR).

A

b. short TI inversion recovery (STIR).

a fast inversion recovery imaging method in which the signal from fat is suppressed

3
Q

c. fluid attenuated inversion recovery (FLAIR).

A

c. fluid attenuated inversion recovery (FLAIR).

a fast inversion recovery imaging method in which the signal from CSF is suppressed

4
Q

d. steady state.

A

d. steady state.

a gradient echo imaging method

in which the TR is shorter than the T1 and T2 times of the tissues

so relaxation does not occur between TR periods

5
Q

e. coherent or unspoiled residual transverse magnetization.

A

e. coherent or unspoiled residual transverse magnetization.

a gradient echo imaging method

in which the transverse magnetization is maintained,

producing T2* weighted images

6
Q

f. incoherent or spoiled residual transverse magnetization.

A

f. incoherent or spoiled residual transverse magnetization.

a gradient echo imaging method

in which the transverse magnetization is spoiled by an RF pulse or a gradient reversal,

producing T1 or proton density weighted images

7
Q

g. echo planar imaging (BPI).

A

g. echo planar imaging (BPI).

an imaging method in which all lines of k-space are filled in a single TR period

8
Q

h. echo train.

A

h. echo train.

the string of 180° RF pulses that are applied during a single TR period in a fast spin echo sequence

9
Q

i. echo train length (ETL) or turbo factor.

A

i. echo train length (ETL) or turbo factor.

the number of 180° RF pulses that are applied during each TR period in a fast spin echo sequence

10
Q

j. effective TE.

A

j. effective TE.

TE at which the central portion of k-space is filled in a fast spin echo sequence; determined image contrast

11
Q

k. echo spacing.

A

k. echo spacing.

the length of time (in msec) between each echo in an FSE/TSE pulse sequence

12
Q

l. rewinder gradient gradient pulse

A

l. rewinder gradient gradient pulse

used to preserve transverse magnetization in a coherent or unspoiled gradient echo pulse sequence

13
Q

m. spoiler gradient or RF pulse.

A

m. spoiler gradient or RF pulse.

gradient pulse used to destroy transverse magnetization in a spoiled or incoherent gradient echo pulse sequence

14
Q

n. stimulated echo.

A

n. stimulated echo.

the spin echo that is produced by any two RF pulses.

15
Q

o. chemical or spectral presaturation.

A

o. chemical or spectral presaturation.

a destructive RF pulse that is applied at the resonant frequency of a specific tissue in order to suppress signal from the tissue

16
Q

p. spatial presaturation.

A

p. spatial presaturation.

an area of destructive RF that is applied to a certain area of the body in order to suppress signal from that area

17
Q
  1. explain why fast spin echo sequences have shorter scan times than conventional spin echo sequences.
A
  1. explain why fast spin echo sequences have shorter scan times than conventional spin echo sequences.

several phase encoding steps in k-space are performed during each TR period

18
Q
  1. identify what area of k-space is filled with echoes centered about the effective TE.
A
  1. identify what area of k-space is filled with echoes centered about the effective TE.

central lines of k-space

19
Q
  1. explain the relationship between echo train length and scan time.

as echo train length increases, scan time _____

A
  1. explain the relationship between echo train length and scan time.

as echo train length increases, scan time decreases

20
Q
  1. identify the difference in the appearance of fatty tissue on conventional and fast spin echo sequences.

fat tends to remain _____ on fast spin echo images

A
  1. identify the difference in the appearance of fatty tissue on conventional and fast spin echo sequences.

fat tends to remain brighter on fast spin echo images

21
Q
  1. explain the relationship between echo train length and the number of slices available per TR period.

as echo train length increases, the number of slices available per TR period _____

A
  1. explain the relationship between echo train length and the number of slices available per TR period.

as echo train length increases, the number of slices available per TR period decreases

22
Q
  1. identify the image artifact that is possible when selecting long echo train lengths and short TR/TE.
A
  1. identify the image artifact that is possible when selecting long echo train lengths and short TR/TE.

blurring

23
Q
  1. explain the advantage of shorter echo spacing.
A
  1. explain the advantage of shorter echo spacing.

less blurring

24
Q
  1. identify the pulse sequence parameter that most affects echo spacing.
A
  1. identify the pulse sequence parameter that most affects echo spacing.

receive bandwidth

25
Q
  1. identify the tissue signal that is suppressed with FLAIR imaging.
A
  1. identify the tissue signal that is suppressed with FLAIR imaging.

CSF

26
Q
  1. identify the tissue signal that is suppressed with STIR imaging.
A
  1. identify the tissue signal that is suppressed with STIR imaging.

fat

27
Q
  1. identify the image weighting that is achieved with STIR and FLAIR imaging.
A
  1. identify the image weighting that is achieved with STIR and FLAIR imaging.

T2

28
Q
  1. explain whether conventional or fast spin echo is most feasible for STIR and FLAIR imaging and why.
A
  1. explain whether conventional or fast spin echo is most feasible for STIR and FLAIR imaging and why.

fast spin echo because imaging times are too long with conventional spin echo

29
Q
  1. identify what type of imaging is used to achieve the steady state.
A
  1. identify what type of imaging is used to achieve the steady state.

gradient echo

30
Q
  1. explain how the TR of a sequence is selected in relation to the T1 and T2 of the tissues to achieve the steady state.

TR must be _____ than T1 and T2

A
  1. explain how the TR of a sequence is selected in relation to the T1 and T2 of the tissues to achieve the steady state.

TR must be shorter than T1 and T2

31
Q
  1. identify the two ways that the transverse magnetization can be spoiled in gradient echo imaging.
A
  1. identify the two ways that the transverse magnetization can be spoiled in gradient echo imaging.

semi-random RF pulses and semi-random gradient reversals

32
Q
  1. identify which method of spoiling is more efficient.
A
  1. identify which method of spoiling is more efficient.

RF spoiling

33
Q
  1. identify which type of gradient echo sequence depends mostly on T2 relaxation for tissue contrast.
A
  1. identify which type of gradient echo sequence depends mostly on T2 relaxation for tissue contrast.

unspoiled or coherent

34
Q
  1. identify which type of gradient echo sequence depends mostly on T1 relaxation for tissue contrast.
A
  1. identify which type of gradient echo sequence depends mostly on T1 relaxation for tissue contrast.

spoiled or incoherent

35
Q
  1. explain the purpose of the rewinder gradient in an unspoiled gradient echo sequence.
A
  1. explain the purpose of the rewinder gradient in an unspoiled gradient echo sequence.

rephases the residual transverse magnetization so it is preserved for the next excitation.

36
Q
  1. explain the amount of k-space that is filled during each TR period in echo planar imaging (EPI).
A
  1. explain the amount of k-space that is filled during each TR period in echo planar imaging (EPI).

All lines of k-space.

37
Q
  1. identify the main magnetic field strengths’at which chemical or spectral presaturation works best and why.
A
  1. identify the main magnetic field strengths’at which chemical or spectral presaturation works best and why.

high field strength because there is more chemical shift
between tissues, which makes them easier to selectively saturate

38
Q
  1. explain the relationship between the precessional frequencies of fat and water.
A
  1. explain the relationship between the precessional frequencies of fat and water.

fat precesses about 3.5 ppm slower than water

39
Q
  1. identify 2 types of motion that are commonly compensated for with spatial presaturation bands.
A
  1. identify 2 types of motion that are commonly compensated for with spatial presaturation bands.

blood flow motion and respiratory motion

40
Q
  1. identify 2 image artifacts that can be compensated for with spatial presaturation bands.
A
  1. identify 2 image artifacts that can be compensated for with spatial presaturation bands.

phase mismapping or ghosting, and aliasing

41
Q
  1. explain the disadvantage of spatial or spectral presaturation in a sequence.
A
  1. explain the disadvantage of spatial or spectral presaturation in a sequence.

fewer slices available per TR when these RF pulses are added

42
Q
  1. explain how a spatial presaturation band can compensate for aliasing artifact.
A
  1. explain how a spatial presaturation band can compensate for aliasing artifact.

the pre-sat band is placed over the anatomy that is outside the FOV