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MRI > Basic Physics And Brief History > Flashcards

Basic Physics And Brief History Flashcards

1
Q

Base on the physic principle of nuclear magnetic resonance (NMR), 1st describe in the 1930s and 40s

A

Magnetic resonance imaging (MRI)

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2
Q

Part of electromagnetic spectrum that includes visible light and x-rays

A

Radio frequency energy

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3
Q

In electromagnetic spectrum where is the radio frequencies located?

A

Far left

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4
Q

In electromagnetic spectrum where is the visible light located?

A

Middle

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5
Q

In electromagnetic spectrum where is the x-rays located?

A

Far right

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6
Q

All of these waved are defined by?

A

Wavelength and frequency

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7
Q

The __ is the distance between peaks of wave

A

Wavelength

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8
Q

Is how many cycles are completed in a seconds

A

Frequency

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9
Q

Is the height or power of the wave

A

Amplitude

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10
Q

When talking! About 2 or more waves we can also describe a?

A

Phase

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11
Q

Blue and orange waves have the same frequency and line up completely so they are also?

A

In phase

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12
Q

If we shift the orange wave to the right the frequency remains __ but the waves are now?

A

The same, out of phase

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13
Q

Described by their unique phase and frequency

A

Radio frequency signals

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14
Q

A point on the computer is called a __ a concatenation of the words picture and element

A

Pixel

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15
Q

Mr images are made up of a series __ or volume and element

A

Voxel

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16
Q

each square on the picture corresponds to a?

A

volume of tissue on the body

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17
Q

The mri machine is designed to measure the __ from each of the small volumes, localized them in 3D space and plot them on a __x__ or __x__ matrix to make a visible picture

A

NMR signal, 256x256, and 512x512

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18
Q

Describe the principles of NMR in a?

A

Single small square or box of tissue

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19
Q

Where a flowing current electrons has an associated magnetic field oriented 90 degrees from the direction of current flow

A

Electromagnetism

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20
Q

The direction of the __ associated with the coil is defined by the right hand rule curl the fingers of your right hand in the direction of the current flow through the coil and your outstretched thumb will point at the direction of the associated ___

A

magnetic field

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21
Q

Consist of a single proton in the nucleus with a single circulating electron orbiting around that proton for the principal of NMR

A

Hydrogen atom

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22
Q

An adult is about 60% in __ which contains two hydrogen atoms for every __

A

Water, oxygen

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23
Q

Ones with little extra energy possibly from some local increased heat will line up against main magnetic field and therefore considered to be in a?

A

High energy state

24
Q

The ones liningg up in with the main magnetic field are in a?

A

Low energy state

25
Q

These protons don’t simply point with or against the main magnetic field they actually precess much like a?

A

Spinning top

26
Q

The rate of __ can be determined exactly by the larmor frequency equation

A

Precession

27
Q

States that the rate of rotation is directly proportional to the strength of the local magnetic field

A

Larmor frequency equation

28
Q

1tesla the larmor frequency of a hydrogen proton or spin is?

A

42.58 megahertz

29
Q

2 tesla

A

85.16 megahertz

30
Q

3 tesla

A

127.74 megahertz

31
Q

Most of the protons are in a __ pointing in the direction of the main magnetic field

A

low energy state

32
Q

Few energetic protons ate oriented against the main magnetic field in the?

A

Higher energy state

33
Q

Even though each proton is precessing in space when you cancel all ths opposing vectors you end up in with a __ pointing with a large main external magnetic field this is called a __

A

Net magnetization vectors, longitudinal magnetization

34
Q

The sinusoidal radio frequency pushes the protons to synchronize and spin together this is the __ portion of an NMR

A

resonance

35
Q

If we add up all the magnetic moment you can see we now have a net magnetic force oriented horizontally or 90 degrees to the longitudinal magnetization this is called the?

A

Transverse magnetization

36
Q

Transverse magnetization can be detected with a?

A

Coil and antenna

37
Q

A current can create a?

A

Magnet

38
Q

A magnet can create a?

A

Current

39
Q

Being all positively charged, will repel each other and move apart as they spread apat we lose that transverse magnetization this process is called? Because it has to do with the interaction of protons or spin themselves

A

T2 or spin spin relaxation

40
Q

No ___ transfer occurs with this relaxation

A

Net energy

41
Q

As these protons fall back down to baseline, we regrow the longitudinal magnetization this is referred to as the? Because it involves the transfer energy from the spins to the surrounding tissues or lattice

A

T1 or spin lattice relaxation

42
Q

As the resonant frequency of the local protons produces a radio signal of the same frequency that can be detected by a coil of wire as the energy is removed the proton first move apart in a? Destroying the transverse magnetization

A

T2 or spin-spin relaxation

43
Q

By changing how quickly we put in the radio frequency energy or the?

A

Repetition time (TR)

44
Q

How quickly we choose to listen to the signal coming back from the transverse magnetization or?

A

Echo time (TE)

45
Q

Process referred to as?

A

Pulse sequence

46
Q

Are accentuated by rapidly exposing the protons to radio frequency energy and keeps the spins in high energy state and thus reducing the effective longitudinal magnetization tissue that recover quickly will have a large signal although slow to recover will have a low signal

A

T1 relaxation effects

47
Q

Are accentuated by a prolonged echo time to allow the spins to move away from each other and accentuate the differences in t2 relaxation between regional tissue or chemicals

A

T2 effect

48
Q

Is obtained with a pulse sequence of a long TR and long TE decreasing the T1 affect with along TE

A

T2 weighted image

49
Q

Is obtained with a pulse sequence of short TR in a short TE enchancing T1 relaxation and minimizing T2 effects

A

T1 weighted image

50
Q

In between these two is the __ which is obtained with a long TR and short TE effectively minimizing T1 and T2 effects and basically giving us idea of the absolute number or density of protons in the region

A

Proton density pulse sequence

51
Q

1st to propose NMR to diagnose disease in human who in march 1971 addition of the journal science published a short article entitled tumor detection by NMR in which he suggested that the NMR signal from tumors of the body could be differentiated from the normal tissue and therefore could be detected

A

Dr. Raymond damadian

52
Q

In conjunction with a standard MR image to help distinguish benign from malignant processes in the body

A

MR spectroscopy

53
Q

We have to be able to localize the signals coming from the sample or tissue in 3D space the 1st to propose a technique to do just that was __ in march 19,1973 addition of nature he published a brief article entitled image formation by induced local interactions he describe a technique using magnetic radiance to identify location of 2 1mm capillsry tubes filled with water both of which were submerged in a larger 4.2 mm tube filled with heavy water

A

Dr. Paul lauterbur

54
Q

Standard hydrogen atom

A

Protium

55
Q

Contains a neutron as well as proton which limits the spin of the nucleus and therefore does not give a good NMR signal

A

Deuterium

56
Q

Dr paul lauterbur called his technique?

A

Zeumatography

MRI (4 decks)

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