Sequence parameters and options

Question 1

the time between excitation pulses is known as the

Answer 1

1/2 TE

Question 2

presaturation pulses are often used to

Answer 2

reduce flow artifacts

Question 3

the presaturation pulses usually occur

Answer 3

prior to the excitation pulse

Question 4

gradient echo sequences use flip angles

Answer 4

to control saturation effects

Question 5

complete saturatoin is a condition where

Answer 5

longitudinal magnetization is not allowed to recover between excitations

Question 6

increasing the TE

Answer 6

increases the contrast based on T2 relazatoin times of the tissue

Question 7

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

Answer 7

decreases the SNR of the image

increases saturatoin effects

Question 8

reducing the TE

Answer 8

reduces contrast base on T2 relaxatoin times

Question 9

as the TR increases

Answer 9

SNR increases up to a point

Question 10

as the TE increases

Answer 10

SNR decreases

Question 11

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

Answer 11

saturation

Question 12

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

Answer 12

TR x NSA x #PEs

Question 13

in an inversion recovery pulse sequence image contrast is controlled by

Answer 13

TR

TE

TI

Question 14

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

Answer 14

TI

Question 15

another name for TI

Answer 15

Tau

Question 16

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

Answer 16

fat

gadolinium enhancing lesion

Question 17

decreaseing the receiver bandwidth

Answer 17

increase the SNR

Question 18

decreaseing the receiver bandwidth

Answer 18

increases readout time

Question 19

decreaseing the receiver bandwidth

Answer 19

increases susceptibility artifact

Question 20

decreaseing the receiver bandwidth

Answer 20

decreases the number of slices

Question 21

increaseing the receiver bandwidth

Answer 21

has no effect on the available ETL

Question 22

the time during which the freq encoding gradient is on

Answer 22

increases with a reduction in reciever bandwidth

Question 23

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

Answer 23

T2 weighting

Question 24

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

Answer 24

FOV

number of slices

Question 25

between slices 2D acquisitions generally require

Answer 25

gaps

Question 26

doubling the number of NSA will

Answer 26

increase the SNR by the square root of 2

Question 27

increasing the number of phse encodings will produce an image with

Answer 27

decreased voxel volume

Question 28

reducing NSA will reduce the scan time and

Answer 28

decrease the SNR

Question 29

doubling the NSA will increase the SNR by a factor of

Answer 29

1.41

Question 30

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

Answer 30

4

Question 31

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

Answer 31

T1

Question 32

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

Answer 32

motoin artifacts traverse the least tissue or areas of interest

Question 33

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

Answer 33

precessional freq of fat

Question 34

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

Answer 34

increases by a factor of 2

Question 35

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

Answer 35

decreases

Question 36

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

Answer 36

slow constant flow

Question 37

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

Answer 37

gradient

Question 38

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

Answer 38

increases by a factor of TR/TE

Question 39

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

Answer 39

decreases

Question 40

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

Answer 40

is not affected

Question 41

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

Answer 41

doubles the scan time

Question 42

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

Answer 42

doubles the scan time

Question 43

the effective TE in a FSE sequence determines the

Answer 43

image contrast

Question 44

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

Answer 44

effective TE

Question 45

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

Answer 45

patients heart rate

Question 46

increasing TR

Answer 46

increases the scan time

Question 47

increasing TE

Answer 47

decreases scan time

Question 48

increasing the number of slices in a 2D acquisition

Answer 48

increases scan time

Question 49

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

Answer 49

the ernst angle

Question 50

increasing the FOV

Answer 50

does not affect scan time

Question 51

increasing the phase matrix

Answer 51

increases scan time

Question 52

increasing slice thickness

Answer 52

does not affect scan time

Question 53

increasing NSA

Answer 53

increases scan time

Question 54

increasing slice thickness

Answer 54

increase SNR

Question 55

increasing the matrix

Answer 55

decreases SNR

Question 56

increasing the flip angle

Answer 56

increases SNR up to the Ernst angle

Question 57

reducing the ETL

Answer 57

increases scan time

Question 58

reducing the TE

Answer 58

increases SNR

Question 59

reducing the TE yeilds images with

Answer 59

less T2 information

Question 60

increasing the TR yeilds images with

Answer 60

less T1 information

Question 61

increasing the TR yeilds images with

Answer 61

less T1 information

Question 62

increasing the TE yeilds images with

Answer 62

more T2 information

Question 63

reducing the TR yeilds images with

Answer 63

more T1 information

Question 64

reducing the flip angle yeilds images with

Answer 64

less T1 information

Question 65

increasing the flip angle yeilds images with

Answer 65

more T1 information