Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MRI Review Part C > Sequence parameters and options > Flashcards

Sequence parameters and options Flashcards

1
Q

the time between excitation pulses is known as the

A

1/2 TE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

presaturation pulses are often used to

A

reduce flow artifacts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

the presaturation pulses usually occur

A

prior to the excitation pulse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

gradient echo sequences use flip angles

A

to control saturation effects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

complete saturatoin is a condition where

A

longitudinal magnetization is not allowed to recover between excitations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

increasing the TE

A

increases the contrast based on T2 relazatoin times of the tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

reducing the TR down to or below the T1 relaxatoin time of the tissue

A

decreases the SNR of the image

increases saturatoin effects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

reducing the TE

A

reduces contrast base on T2 relaxatoin times

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

as the TR increases

A

SNR increases up to a point

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

as the TE increases

A

SNR decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

in a gradient echo sequence reducing the fip angle while holding the TR constant reduces

A

saturation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

in a 2D conventional SE multislipce pulse sequence scan time is given by the equation

A

TR x NSA x #PEs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

in an inversion recovery pulse sequence image contrast is controlled by

A

TR

TE

TI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

in an inversion recovery pulse sequence the time between the initializing 180 pulse and the 90 pulse is known as

A

TI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

another name for TI

A

Tau

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

a short T1 inversion recovery (STIR) sequence can suppress the signal from

A

fat

gadolinium enhancing lesion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

decreaseing the receiver bandwidth

A

increase the SNR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

decreaseing the receiver bandwidth

A

increases readout time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

decreaseing the receiver bandwidth

A

increases susceptibility artifact

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

decreaseing the receiver bandwidth

A

decreases the number of slices

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

increaseing the receiver bandwidth

A

has no effect on the available ETL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

the time during which the freq encoding gradient is on

A

increases with a reduction in reciever bandwidth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

in a conventional spin echo multi echo sequence it is possible to create multiple images each with a different amount of

A

T2 weighting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

the SNR will increase in a 3D sequence with an increase in

A

FOV

number of slices

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

between slices 2D acquisitions generally require

A

gaps

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

doubling the number of NSA will

A

increase the SNR by the square root of 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

increasing the number of phse encodings will produce an image with

A

decreased voxel volume

28
Q

reducing NSA will reduce the scan time and

A

decrease the SNR

29
Q

doubling the NSA will increase the SNR by a factor of

A

1.41

30
Q

reducing the FOV by a factor of 2 will reduce the voxel volume by a factor of

A

4

31
Q

if a STIR sequence using a TR of 3000, TE of 20 and a TI of 140 produces an image with dark fat and birght water, the contrast is such an image is primarily based on

A

T1

32
Q

in choosing the direction of phase encoding the technologist usually consider the direction in which the

A

motoin artifacts traverse the least tissue or areas of interest

33
Q

a chemical or spectral fat suppression sequence will suppress the signal from fat based on the

A

precessional freq of fat

34
Q

increasing slice thickness from 5 to 10 mm (by a factor of 2 x thicker) the SNR

A

increases by a factor of 2

35
Q

in creaseing the number of phase encodings (matrix) from 128 to 256 the SNR

A

decreases

36
Q

gradient moment nulling is most effective when correcting for motion induced signal loss from

A

slow constant flow

37
Q

to rephase the signal from moving spins gradient moment nulling techniques us a

A

gradient

38
Q

using a conventional spin echo multislice sequence the number of slices allowed when increasing TR

A

increases by a factor of TR/TE

39
Q

using a conventional SE multislice sequence the number of slices allowed when increasing the TE from 20 to 40ms

A

decreases

40
Q

using a 3D acquisition the number of slices allowed when in creasing the TR

A

is not affected

41
Q

using a 3D acquisition increasing the number of slices from 64 to 128

A

doubles the scan time

42
Q

increasing the matrix in the freq direction from 256 to 512 will

A

doubles the scan time

43
Q

the effective TE in a FSE sequence determines the

A

image contrast

44
Q

in an FSE sequence the central lines of k space are associated witoh the

A

effective TE

45
Q

when triggering a scan from the patients ECGH the TR of the sequence is determined by the

A

patients heart rate

46
Q

increasing TR

A

increases the scan time

47
Q

increasing TE

A

decreases scan time

48
Q

increasing the number of slices in a 2D acquisition

A

increases scan time

49
Q

for a given tissue with a given T1 relaxation time and TR, the flip angle which will result in the maximum signal for that tissue is

A

the ernst angle

50
Q

increasing the FOV

A

does not affect scan time

51
Q

increasing the phase matrix

A

increases scan time

52
Q

increasing slice thickness

A

does not affect scan time

53
Q

increasing NSA

A

increases scan time

54
Q

increasing slice thickness

A

increase SNR

55
Q

increasing the matrix

A

decreases SNR

56
Q

increasing the flip angle

A

increases SNR up to the Ernst angle

57
Q

reducing the ETL

A

increases scan time

58
Q

reducing the TE

A

increases SNR

59
Q

reducing the TE yeilds images with

A

less T2 information

60
Q

increasing the TR yeilds images with

A

less T1 information

61
Q

increasing the TR yeilds images with

A

less T1 information

62
Q

increasing the TE yeilds images with

A

more T2 information

63
Q

reducing the TR yeilds images with

A

more T1 information

64
Q

reducing the flip angle yeilds images with

A

less T1 information

65
Q

increasing the flip angle yeilds images with

A

more T1 information

MRI Review Part C (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions