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MRI > Week 1 > Flashcards

Week 1 Flashcards

1
Q

is any object that produces its own magnetic field that interacts with other magnetic fields

A

Magnet

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2
Q

Three principal types of magnets:

A

– Natural - Earth
– Permanent
– Electromagnet

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3
Q

are distinguished from permanent magnets by their ability to generate magnetic fields when electric current
flows through them. current to generate magnetism.

A

Electromagnets

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4
Q

usually consist of wire wound into a coil. A current through the wire creates a magnetic field which is concentrated in the hole in the center of the coil

A

Electromagnets

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5
Q

TYPES OF MAGNETS USED IN MRI

A

Superconducting Magnets
Resistive Magnets
Permanent Magnets

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6
Q
  • commonly used magnet nowadays. This magnets operate near absolute zero temperature. Magnetic field above 0.5Tesla. (1-3Tesla)
A

Superconducting Magnets

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7
Q
  • similar to superconductive but wires are not cooled. Magnetic field not higher than 0.6Tesla.
A

Resistive Magnets

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8
Q

– operate to magnetic fields up to 0.4 Tesla. (.15-4T)

A

Permanent Magnets

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9
Q

Types of magnets in terms of
field strengths

A

Ultrahigh field
High field
Midfield
Low field
Ultralow field

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10
Q

(4-7 Tesla)- used for research

A

Ultrahigh field

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11
Q

(1.5-3 Tesla)

A

High field

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12
Q

(0.5-1.4 Tesla)

A

Midfield

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13
Q

(0.2-0.4 Tesla)

A

Low field

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14
Q

(<0.2 Tesla)

A

Ultralow field

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15
Q

Magnetic Susceptibility

A

– Diamagnetic
– Ferromagnetic
– Paramagnetic

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16
Q

-substances have no unpaired orbital electrons. Weakly repelled by either
magnetic poles. Ex. Water and plastic

A

Diamagnetic

17
Q
  • strongly magnetized by a magnet and usually can be permanently magnetized by exposure to a magnetic field. Ex. Alnico
A

Ferromagnetic

18
Q
  • materials lie somewhere between ferromagnetic and nonmagnetic
A

Paramagnetic

19
Q

Weakly repelled from both poles of a magnetic field.
Example:GoldDiamondsLeadSilver

A

Diamagnetic

20
Q

Weakly attracted to both poles of a magnetic field.Example:Gadolinium (excellent contrast agent for
MRI)TungstenAluminum

A

Paramagnetic

21
Q

Can be strongly magnetized
Example:IronNickel

A

Ferromagnetic

22
Q

the unit of the strength of a magnetic field.

A

Gauss & Tesla

23
Q

is the smaller unit of measurement
compared with tesla.1 tesla is equals to
10,000 Gauss

A

Gauss

24
Q

The earth’s magnetic field is about

A

0.5Gauss

25
Q

Is a highly developed innovative technique that provide anatomic images in multiple planes and allows information on tissue characterization.

A

Magnetic resonance imaging

26
Q

–is a vector quantity consisting
of both a north and south pole.

A

Magnetic field

27
Q

– a magnetic field characterized by its own magnetic north and south poles separated by a finite distance

A

Dipole

28
Q

– the amount of magnetic flux in a unit area perpendicular to the direction of magnetic flow.

A

Magnetic intensity

29
Q
  • a device that attracts iron and
    produces a magnetic field. The biggest and the most important part of the MRI system.
A

Magnet

30
Q

– precesses or tumble

A

Spin

31
Q

– the phenomenon of magnetic field spinning or gyrating around imaginary axis of its own creation.

A

Precession

32
Q
  • is the rate at which the
    nuclei complete a revolution about the
    precessional path. (megahertz or millions of
    cycle per second
A

Frequency precession

33
Q

– the ratio between magnetic
moment and angular momentum.

A

Gyromagnetic ratio

34
Q
  • the angle formed between a
    precessing object and its imaginary axis.
A

Angular momentum

35
Q

– is ideal for MRI because its
nucleus has a single proton and a large magnetic moment.

A

Hydrogen atom

36
Q
  • refers to spinning motion of
    positive protons and the negative electrons that create a small magnetic field about the atom
A

Magnetic moment

37
Q
  • refers to that portion of
    the electromagnetic spectrum in which
    electromagnetic waves can be generated by alternating current fed to an antenna.
A

Radiofrequency Pulse

38
Q
  • phenomenon resulting in the
    absorption and/or emission of electromagnetic energy by nuclei or electrons in a static magnetic field, after excitation by a suitable magnetic field.
A

Resonance

39
Q
  • specific frequency of resonance.
A

Larmor Frequency

MRI (3 decks)

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