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MRI - The beginning > Module 1 > Flashcards

Module 1 Flashcards

1
Q

More powerful the External Magnetic Field

A

the more N.M.V. there are to manipulate.

Net Magnetization Vectors

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2
Q

How is the field strength of the magnet displayed

A

in tesla represented as T

or Bo

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3
Q

Path by which the Hydrogen Atoms follow.

A

Precessional Path:

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4
Q

Hydrogen Atom Nucleus is rotating around its axis and the Proton or charged particle is also rotating which causes the hydrogen atom to have its own _____ _____

A

This causes the Hydrogen atom to contain its own Magnetic Field

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5
Q

The sum of Protons and Neutrons in the nucleus

A

Atomic Mass

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6
Q

Due to its odd number of Protons (one) in its nucleus. (hydrogen atom) start to proceed around causing a _____ _____.

A

Magnetic Moment that is relatively large

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7
Q

To line up with the Magnetic Field, it takes more or less energy

A

Less energy

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8
Q

MRI advantages

A
  1. Non-ionizing radiation.
  2. Spatial resolution (the ability to distinguish two points or structures as separate)
  3. Contrast resolution
  4. Multiplanar Imaging
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9
Q

Hydrogen Nuclei spin on there own axis.

Once subjected to an External Magnetic Field they also start to wobble

A

This wobble is called its Precession

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10
Q

With no external magnetic field, magnetic moments are randomly situated.

Once exposed to a Magnet Field M. M. start to_______with and against Magnetic field (North and South)

A

align

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11
Q

Size and Direction of the magnetic moment in the Z plane.

has both magnitude and direction and is called a _____.

A

Vector

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12
Q

This refers to three inividual forces: motion, magnetism and electrical charge.

If two of the three are present then the third will be induced

A

Faraday’s law of electromagnetic induction

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13
Q

Disadvantage of MRI

A

Expensive

Long scan times

Audible noise (65-115dB or higher)

Isolation of patient (claustrophobia, monitoring of ill patients)

Exclusion of patients with conventional pacemakers and certain implants.

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14
Q

This energy state aligns with the External Magnetic Field, termed Spin Up Nuclei.

A

Low energy state

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15
Q

It takes more or less energy to fight against the direction of the Main Magnetic Field.

A

More energy

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16
Q

Godfather of MRI

A

Felix Bloch

17
Q

Speed at which the Hydrogen Atoms spin we also call this wobble

A

Precessional Frequency:

18
Q

This is the sum of Protons in Nucleus

A

Atomic Number

19
Q

This is equal to the gyromagnetic Ratio of Hydrogen (42.57MHZ/Tesla) x the Magnetic Field Strength

A

The Precessional Frequency

20
Q

Precessional Frequency is represented

A

as f

or Wo

21
Q

This energy state aligns against the External Magnetic Field, termed Spin Down Nuclei.

A

High energy state

22
Q

The gyromagetic ratio is represented by

A

Greek gamma symbol

23
Q

Consists of central nucleus with one proton, no neutron, and one orbiting electrons

A

Hydrogen Atom

24
Q

3T images have _______ signal than 1.5T.

25
Q

42.57 MHZ/T

A

Larmar equation ratio

26
Q

These are the winners or the remaining Vectors that now align with the external field…

These are what will be manipulated by the external R.F. pulse to create M.R.I images.

A

Net Magnetization Vectors

27
Q

The third force of Faraday’s law, magnetism, will be induced thus giving the hydrogen atom a magnetic moment allowing it to align with an external magnetic field.

A

hydrogen we have a positive charge and motion

28
Q

Battle between Spin Up and Spin Down Nuclei create a common ground. The result of this battle is the

A

N.M.V. w0

Net Magnetization Vector

29
Q

Images are created using 3 regions of the electromagnetic spectrum.

A

X-rays use transmitted x-rays

Photographs use reflected visible light.

MRI uses emitted radiofrequencies

30
Q

3 Types of Motion within the Hydrogen Atom

A

Electrons spinning on own axis

Electrons orbiting the Nucleus

The Nucleus itself spins on own axis

31
Q

The larger the field strength, the ________hydrogen will align in the spin up (low energy) state

32
Q

This is a test that uses a magnetic field and pulses of radio wave energy to make pictures of organs and structures inside the body

A

What is MRI

33
Q

Determines the Precessional Frequency

A

Larmor equation:

34
Q

This is direction of the North and South axis of a Magnet and the amplitude of the magnetic field

A

magnetic moment

35
Q

In a patient, the tissues that behave like tiny magnets themselves and are susceptible to an external magnetic field due to its magnetic moment

A

hydrogen nuclei

36
Q

The Hydrogen nuclei can have two types of energy states.

What are they?

A

Low State

High State

MRI - The beginning (1 decks)

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