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329 - MRI imaging production & procedures > unit 2 > Flashcards

unit 2 Flashcards

1
Q

secondary coils around the magnet, used to contain, or reduce the main magnetic fringe field

A

active shielding

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2
Q

• adjusts the current on a certain sequence or patient
• helps achieve uniform fat suppression for images that call for it
• improves the magnet’s homogeneity

A

active shimming

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3
Q

• main static field of the MR system
- Z-axis , Longitudinal axis

A

B0 field

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4
Q

• alternating magnetic field created by the RF in a coil
- perpendicular to B0

A

B1 field

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5
Q

voltage created in the receiver coil , due to a change in the magnetic field

A

electromagnetic induction

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6
Q

uniformity of magnetic field, if you do not have it causes artifact on images

A

homogeneity

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7
Q

where the magnet bore assigns all the axis (X,Y,Z) =0
- the centering point of all the coordinates
- center of the bore and magnetic field

A

isocenter

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8
Q

magnetic forces running from a north and south pole to form a closed loop around the outside of the magnetic material
- has both strength and direction
- measured in tesla

A

magnetic field

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9
Q

lining around the MR room with steel or other type of ferromagnetic material
- reduces the scope and distance of the fringe field

A

passive shielding

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10
Q

placing metal sheets within the magnet to create a more homogeneous magnetic field

A

passive shimming

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11
Q

magnet that generates magnetic field with the use of ferromagnetic materials
- no super cooling or additional power source needed
- typically a lower field strength

A

permanent magnet

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12
Q

frequency band in the electromagnetic spectrum

A

radio frequency

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13
Q

can transmit, receive, or both of the RF signal
- create magnetic field opposite (B1) of the main magnet field (B0)
- responsible for detecting the MR signal

A

radio frequency coil

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14
Q

a magnet that can be turned on and off, uses electromagnetism to create the magnetic field

A

resistive magnet

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15
Q

exchange of energy between two sources at a specific frequency

A

resonance

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16
Q

coils that have a small current and provide localized magnetic fields, thus improving total field homogeneity

A

shim coils

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17
Q

process of improving homogeneity of the magnetic field
- active or passive

A

shimming

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18
Q

generates its magnetic field by using current in wires made of a superconducting material
- cooled with cryogens
- higher field systems

A

superconducting magnet

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19
Q

surface coil that both transmits and receives RF signal

A

transceiver coil

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20
Q

part of the MR scanner that produces the RF current and send it to the transmitting coil

A

transmit coil

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21
Q

3 main components of a MRI system / suite

A
  • the gantry
  • operating console
  • the system electronics
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22
Q

high magnetic field is considered

A

1.5 T or higher

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23
Q

most common magnetic field strength

A

1.5 T

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24
Q

used when imaging the pituitary gland

A

dynamic contrast enhanced

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25
Q

important series for stroke imaging

A

DWI

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26
Q

reconstructed from diffusion weighted images, with multiple b-values, and corresponds to the distributed coefficients of the target tissues

A

ADC

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27
Q

movement of atoms or molecules from an area of high concentration to lower concentration

A

diffusion

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28
Q

a factor in diffusion weighted imaging the higher the number, the stronger the diffusion

A

b-value

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29
Q

inflammation of the fatty myelin sheaths around the axons of the brain and spinal cord

A

multiple sclerosis

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30
Q

tumor of greater than 1 cm in the pituitary gland

A

macro-adenoma

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31
Q

rupture of blood flow in the brain, causing a hemorrhage

A

cerebrovascular attack

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32
Q

temporary blockage of blood flow in the brain

A

transient ischemia attack

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33
Q

axial slices should be set up / plotted

A

inferior to superior

34
Q

which series(s) can help reduce patient motion

A

propeller
blade

35
Q

when plotting the sagittal images from the coronal localizer the slices should be plotted

A

left to right

36
Q

the coronal slices, in a routine brain, need to cover through the ________ anteriorly

A

frontal sinuses

37
Q

in a routine brain scan, the coronal slices should be set up / plotted

A

posterior to anterior

38
Q

if you have to perform the oblique cervical spine images, what structure are you making the oblique slices perpendicular to?

A

lamina

39
Q

in the lumbar spine, images acquired directly through the intervertebral disc spaces can be acquired in the ______ plane

A

axial

40
Q

sagittal spine slices are prescribed in which direction

A

left to right

41
Q

when setting up sagittal slices for the lumbar spine, the coverage should include

A

transverse process to transverse process

42
Q

how often should imaging coils be inspected for safety

A

every time you use them

43
Q

1 T is equal to _____ gauss

A

10,000

44
Q

the liquid helium used to cool that magnet’s could has a temperature of

A

-452 degrees fahrenheit

45
Q

5 gauss is equivalent to ___ T

A

0.0005 tesla

46
Q

how many pairs of gradients are there

A

3

47
Q

T/F: the localization light can possibly cause eye damage

A

true

48
Q

the axial slices of the brain should be set up initially on the _________ localizer, then the remaining two of the localizer images

A

sagittal

49
Q

the axial slices for the routine brain, should be set up

A

parallel to the inferior border of the genu of the corpus callosum and the splenium of the corpus callosum

50
Q

the sagittal slices should be set up ______ to the midline of the brain

A

parallel

51
Q

in an axial T2 image of the brain, fluids will appear

A

bright / white

52
Q

the centering point for the localizer when doing a brain scan should be the patients

A

glabella / nasion

53
Q

on a T1 weighted image, the CSF will appear

A

hypointense (dark) to the spinal cord

54
Q

when imaging the t spine, how many blocks / sets of slices are typically set up when doing axials

A

two

55
Q

T/F: contrast enhancement is good to visualize the MS plaques within the spinal cord canal

A

true

56
Q

most inferior portion of the spinal cord

A

conus medullaris

57
Q

spinal cords ends at the level of

A

L1-L2

58
Q

anchors the spinal cord to the coccyx

A

filum terminale

59
Q

spinal coil for lumbar spine

A

multi coil/ phased array

60
Q

horizontal alignment light for L spine corresponds to the

A

third lumbar spine (L3)

61
Q

scar tissue enhances ______ after contrast injection

A

immediately

62
Q

when distance between the edges of the disc material is greater than the distance at the base

A

extrusion

63
Q

horizontal light is centered where for t spine

A

level of 4th thoracic vertebra

64
Q

SNR is dependent on the

A

quality of the coil

65
Q

use ______ to minimize aliasing

A

oversampling

66
Q

cancer that starts in the plasma cells in bone marrow

A

multiple myeloma

67
Q

the medical term for a tumor that begins in the brain or spinal cord

A

glioma

68
Q

pulse motion of the CSF within the spinal canal produces ________

A

phase ghosting

69
Q

oval mass in spinal canal

A

spinal meningioma

70
Q

coils located inside the bore of magnet, produces a magnet field that goes along the Z axis

A

gradient system

71
Q

T1 weighted images are good for

A

anatomy identification

72
Q

DWI is most often acquired using a _____ EPI sequence

A

T2 weighted

73
Q

pathology will be bright on these images

A

axial T2 flair

74
Q

demonstrates the most magnetic susceptibility, great at showing hemorrhage in a stroke patient

A

axial GRE

75
Q

T1 , 3D / volume acquisition, helps see difference between white and gray matter

A

axial BRAVO

76
Q

derived from multiple diffusion weighted series , multiple b values , usually done post processing

A

axial ADC

77
Q

contrast is done with

A

T1 weighted sequences

78
Q

less affected by chemical shift, good for microbleeds , 3D imaging

A

SWAN

79
Q

FLAIR

A

fluid attenuated inversion recovery
* fluid suppression , CSF is nulled

80
Q

suppresses fat signal

A

STIR

329 - MRI imaging production & procedures (10 decks)

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