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329 - MRI imaging production & procedures > unit 3 > Flashcards

unit 3 Flashcards

1
Q

what sequence suppresses fat

A

STIR

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2
Q

what does TE stand for

A

echo time

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3
Q

what does TI stand for

A

inversion time

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4
Q

what does TR stand for

A

repetition time

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5
Q

what sequence removes CSF signal

A

FLAIR

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6
Q

GRE stand for

A

gradient echo

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7
Q

FSE stands for

A

fast spin echo

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8
Q

PD stands for

A

proton density

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9
Q

NEX stands for

A

number of excitations

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10
Q

your planning scan is known as

A

scout / localizer

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11
Q

number of echos after an excitation pulse

A

echo train length (ETL)

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12
Q

time between excitation and the middle of the readout process

A

echo time (TE)

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13
Q

time between the inversion pulse and 90 degree pulse

A

inversion time (TI)

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14
Q

the slice region actually displayed

A

FOV

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15
Q

what does FS stand for

A

fat saturation

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16
Q

what sequence would best demonstrate MS plaques

A

T2 FLAIR

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17
Q

gadolinium is best seen on what type of weighted image

A

T1

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18
Q

it is required that the mri table/couch be able to be accurate within _____ of setting

A

+/- 1mm

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19
Q

measures coil sensitivity before the scan, usually very short & blurry image

A

pre calibration scan / asset

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20
Q

the coronal plane is associated with which axis

A

Y axis

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21
Q

coronal images typically start by using which localizer

A

sagittal , starting posterior & ending anterior

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22
Q

the sagittal plane is associated with which axis

A

x-axis

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23
Q

the sagittal image is typically plotted on which localizer

A

coronal , starting with patients left & ending right

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24
Q

the axial plane is associated with which axis

A

Z-axis

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25
Q

the axial image is typically plotted of which localizer

A

sagittal
inferior to superior - brain
superior to inferior - other studies

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26
Q

do thick or thin slices cover more of the patients body tissue

A

thick slices

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27
Q

what changes the voxel volume along the dimension of the slice

A

changes in the slice thickness

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28
Q

thicker slices give a ______ SNR, but a ______ spatial resolution

A

higher , lower

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29
Q

the distance between two slices

A

slice gap “aka skip”

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30
Q

RF could excite adjacent slices if too close, or overlap

A

crosstalk

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31
Q

you want a slice gap of at least ____ of the slice thickness to prevent cross talk

A

30%

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32
Q

a thin slice of gap

A

1mm/1mm to 4mm/1.5mm or less

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33
Q

a medium slice gap

A

5mm/ 2.5mm to 6mm/ 2.5mm

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34
Q

a large slice gap

A

8mm/2mm or more

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35
Q

the short axis of the image

A

phase matrix

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36
Q

phase matrix

A

coronal image = horizontal axis (X-axis)
sagittal image = vertical axis (Y-axis)
axial image = vertical axis (Y-axis)
-except head & brain image
* horizontal axis (X-axis)

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37
Q

the number of phase encodings determines the

A

number of lines in k-space that are filled to complete the scan

38
Q

larger the number of a phase matrix =

A

the longer scan time

39
Q

reducing the phase matrix =

A

reduces scan time
* assuming the field of view remains the same

40
Q

the number of data points collected during the acquisition time

A

frequency matrix

41
Q

the time between successive pulse sequences or excitation (RF) pulses for a particular slice

A

TR, repetition time

42
Q

repetition time is measured in

A

ms

43
Q

TE is always ______ than TR

A

shorter

44
Q

determines the amount of T1 weighting used in the imaging contrast

A

TR , repetition time

45
Q

longer TR =

A

longer scan time & vice versa

46
Q

short TR is considered

A

under 500 ms

47
Q

time between the excitation and the middle of the readout process

A

TE , echo time

48
Q

the length of time from one 90 degree RF pulse to the next 90 degree RF pulse in a given slice
* determines the amount of T2 weighting for spin echo images

A

TE, echo time

49
Q

number of times each k-space line if filled with data

A

NEX, number of excitations / number of signal averages

50
Q

the higher the NEX/NSA number =

A

the more data that is stored in each line of k space

51
Q

the higher the NEX =

A

more/longer scan time

52
Q

image acquisition time is _______ to ETL (echo train length)

A

inversely proportional

53
Q

the ____ is the voltage induced in the receiver coil , the intensity of the information

A

signal

54
Q

the ____ is a random value depending on the area under examination

A

noise

55
Q

the easiest way to increase SNR is to

A

increase NSA/NEX

56
Q

what parameters changes can cause a decrease in SNR

A

increasing TE
increasing matrix
reducing slice thickness

57
Q

typically a good _____ is the most important factor

A

SNR

58
Q

as a technologist our goal is to achieve optimal images with

A

high SNR
good spatial image resolution
short acquisition/scan time

59
Q

can decrease scan time by

A

using a short TR
a coarse phase matrix
the lowest NEX/NSA possible

60
Q

sometimes the extremity coil is called a

A

“chimney coil”

61
Q

if you are scanning a forefoot make sure to include all

A

toes in all imaging planes

62
Q

where do you center for a fore foot exam

A

metatarsals

63
Q

axial of the foot should be scanned

A

perpendicular to the long axis of the foot, should show metatarsals in cross section

64
Q

axials of the foot are plotted

A

superior to inferior

65
Q

coronals of the foot are scanned

A

with the short axis of the foot , angle parallel to the 2 & 3rd metatarsal heads

66
Q

if you give contrast for a foot you are probably looking for

A

osteomyelitis or another infection

67
Q

this condition is thought to be due to chronic entrapment of the nerve by the intermetstarsal ligament

A

morton’s neuroma

68
Q

this condition is thought to be due to chronic entrapment of the nerve by the intermetstarsal ligament

A

morton’s neuroma

69
Q

horizontal alignment light for the ankle

A

passes through the level of the malleoli

70
Q

horizontal alignment light for the ankle

A

passes through the level of the malleoli

71
Q

in the sagittal image of the ankle you should be able to visualize

A

the base of the 5th metatarsal

72
Q

in which direction should you prescribe the axial slices in the ankle

A

superior to inferior

73
Q

if scanning the entire lower leg (tib fib) what anatomy are you including

A

femoral condyles to the calcaneus

74
Q

coronals & sagittals of the tib fib are

A

parallel to the shaft of the tibia

75
Q

what coil type can be used for a knee MRI

A

phased array coil

76
Q

proper centering of the knee in the coil is essential to avoid

A

drop off of signal

77
Q

clear display of the ____ is essential in knee exams for pain , trauma, or suspected joint damage

A

ACL

78
Q

sagittal images of the knee should include

A

both the lateral and medial collateral ligaments

79
Q

coronals of the knee are aligned

A

parallel to the posterior surfaces of the femoral condyles

80
Q

prevents anterior displacement of the tibia

A

ACL

81
Q

when scanning a knee to visualize the ACL a slight ________ rotation of the knee is required

A

external , about 15 degrees

82
Q

the most common mass in the popliteal fossa

A

bakers cyst , also termed popliteal cyst

83
Q

MR arthrography of the knee is used for the diagnosis of

A

meniscal tears & chondral defects

84
Q

what series of the foot is done pre and post contrast typically

A

T1 FS

85
Q

for venous study of the lower leg, the axial slices should be set up going ______ to ______ due to the blood flow direction

A

superior, inferior

86
Q

on an image that is proton dense and fat suppressed, the fracture would/ should appear

A

white

87
Q

best views for the evaluation of the ACL include

A

sagittal & oblique

88
Q

increasing NEX will increase

A

SNR

89
Q

all ways to reduce metal artifact if a pat has a prosthetic hip

A

wider bandwidth
higher NEX/NSA
higher ETL
TSE/FSE
STIR
Mavric

90
Q

patients with a hip replacement may experience ________ SAR and/or warmth of the body

A

higher

329 - MRI imaging production & procedures (3 decks)

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