MRI MAGNET

Question 1

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

Answer 1

Magnet

Question 2

Three principal types of magnets:

Answer 2

– Natural - Earth
– Permanent
– Electromagnet

Question 3

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

Answer 3

Electromagnets

Question 4

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

Answer 4

Electromagnets

Question 5

TYPES OF MAGNETS USED IN MRI

Answer 5

Superconducting Magnets
Resistive Magnets
Permanent Magnets

Question 6

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

Answer 6

Superconducting Magnets

Question 7

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

Answer 7

Resistive Magnets

Question 8

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

Answer 8

Permanent Magnets

Question 9

Types of magnets in terms of
field strengths

Answer 9

Ultrahigh field
High field
Midfield
Low field
Ultralow field

Question 10

(4-7 Tesla)- used for research

Answer 10

Ultrahigh field

Question 11

(1.5-3 Tesla)

Answer 11

High field

Question 12

(0.5-1.4 Tesla)

Answer 12

Midfield

Question 13

(0.2-0.4 Tesla)

Answer 13

Low field

Question 14

(<0.2 Tesla)

Answer 14

Ultralow field

Question 15

Magnetic Susceptibility

Answer 15

– Diamagnetic
– Ferromagnetic
– Paramagnetic

Question 16

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

Answer 16

Diamagnetic

Question 17

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

Answer 17

Ferromagnetic

Question 18

• materials lie somewhere between ferromagnetic and nonmagnetic

Answer 18

Paramagnetic

Question 19

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

Answer 19

Diamagnetic

Question 20

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

Answer 20

Paramagnetic

Question 21

Can be strongly magnetized
Example:IronNickel

Answer 21

Ferromagnetic

Question 22

the unit of the strength of a magnetic field.

Answer 22

Gauss & Tesla

Question 23

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

Answer 23

Gauss

Question 24

The earth’s magnetic field is about

Answer 24

0.5Gauss

Question 25

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

Answer 25

Magnetic resonance imaging

Question 26

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

Answer 26

Magnetic field

Question 27

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

Answer 27

Dipole

Question 28

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

Answer 28

Magnetic intensity

Question 29

- a device that attracts iron and produces a magnetic field. The biggest and the most important part of the MRI system.

Answer 29

Magnet

Question 30

– precesses or tumble

Answer 30

Spin

Question 31

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

Answer 31

Precession

Question 32

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

Answer 32

Frequency precession

Question 33

– the ratio between magnetic moment and angular momentum.

Answer 33

Gyromagnetic ratio

Question 34

- the angle formed between a precessing object and its imaginary axis.

Answer 34

Angular momentum

Question 35

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

Answer 35

Hydrogen atom

Question 36

- refers to spinning motion of positive protons and the negative electrons that create a small magnetic field about the atom

Answer 36

Magnetic moment

Question 37

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

Answer 37

Radiofrequency Pulse

Question 38

- 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.

Answer 38

Resonance

Question 39

- specific frequency of resonance.

Answer 39

Larmor Frequency