MRI Flashcards

1
Q

name origianlly used for MR

disassociated from MRI because of public apprehension about nuclear energy

A

Nuclear Magnetic Resonance (NMR)

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2
Q

bloch and purcell discovered properties of MR which led to the use of MRE spectroscopy

A

1940s

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3
Q

bloch and purcell awared nobel prize in physics

A

1952

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4
Q

damadian showed that the relaxation of water in a tumor differed from that of water in a normal tissue
relaxation time represents the rates of signal decay and the return pf protons to equilibrium

A

1960s

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5
Q

paul lauterbur published the first crude cross-sectional images of objects obtained with MRI

A

1973

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6
Q

Peter mansfield further showed how the signals could be mathmatically analyzed which made it possible to develop a useful imaging technique

A

1973

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7
Q

nobel prize in physiology or medicine was awarded to bot lauterbur and mansfiel for their discovers in MRI

A

2003

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8
Q

protons in certain nuclie, if placed in a magnetic field

can be stimulated by radio waves of the correct frequency

A

basic principle of MRI

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9
Q

nucleus, electrons, protons,

A

structures of atom

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10
Q

after protons align with magnetic field rotation occurs

action called precession

A

role of magnetic field

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11
Q

RF introduced as very fast burst of radio waves

A

introdcution of RF pulses

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12
Q

based on nuclear density, relaxation rates and flow

strong signals appear white, weak signals, appear black

A

MRI signals

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13
Q

number of processing nuclie in a give volume of tissue

becuase the hydrogen nucleus is a single proton, its nuclear concenetration is referred to as

A

proton density

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14
Q

one component of relaxation is the release of energy by the excited protons
occurs at different rates in different tissues

A

relaxation time

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15
Q

process of nuclei releasing excess energy to the general environment or lattice, also called spin-lattice relaxation

A

T1 relaxation rate

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16
Q

release of energy by excited nuclei through interaction amoung themselves

A

T2 realaxation rate

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17
Q

moving substance usually have weak MRI signals

18
Q

specific radio-wave pulses that stimulate the nuclei

A

pulse sequence

19
Q

controls the computer
displays the images
images may be printed

20
Q

houses the electronics necuessary for transmitting radio-wave pilse sequences
can store raw and reconstructed date temporarily

A

computer room

21
Q

contains major components of the MRI unit, the magnet

A

magnent room

22
Q

simple but large electromagnet consisting of coils of wires
large amount of current is passed through a large number of coils to produce high magnetic fields
requires cooling system to offset heat produced

A

resistive magnent

23
Q

wire loops are cooled to very low temperatures with liquid helium to reduce electrical resistance thereby producing higher magnetic field strenghts compared to resistive magnets

A

superconductive (cryogenic) magnent

24
Q

constant field that does not require additional electriciyt or cooling

A

permanent magnent

25
antennas required for transmitting the RF pulse and receiving MRI signals
coils
26
sagittal, coronal, transverse, oblique
planes
27
important for visualizing pathology
slice thickness
28
long time, more signal available
imaging time
29
depending on pulse sequence, resulting images may be more weighted toward proton density, T1 or T2 information
imaging sequence
30
classic sequence for T1 weighted images can also provide proton density- weighted images and T2 weighted images useful when high signal from extensive fat overwhelms small signal intenstiy differences in the tissue of interest
spin echo
31
a sequence that accentulates T-1 information and provides timimg parameter to minimize signla intensity in tissue
inversion recovery
32
useful when high signal from extensive fat overwhelms small signal intensity difference in the tissue of interest
fat-suppressed
33
the only MRI contrast approved in the US, commonly used in CNS studies metal with paramagentic effect shortens T1 relaxation time producing high contrast images intravenoulsy administered
gadolinium
34
imaging technique used to improve image quality
gating
35
MRI superior over CT for imaging posterior fossa and white matter disease such as MS
Central Nervous System
36
lungs and blood in the great vessel have low MRI signals | FDA approved MRI in 1991 for supplemental mammogrpahy
chest
37
MRI more sensitive than CT in detecting primary and metastic tumors of the liver
abdomen
38
MRI advantageou in coronal and saggittal plane in examing the curvature of the pelvis
pelvis
39
limbs, bone marrow as well as joints are well visualized
musculoskeletal system
40
carotid arteries for stenoses, aneurysms plaques
vessles