Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MIDTERMS - 3RD YR TRANSES > MRI (2) > Flashcards

MRI (2) Flashcards

1
Q

discovered the __ in __in Budapest, Hungary. This was a fundamental discovery in physics

A

Nikola Tesla; Rotating Magnetic Field ;1882

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

In 1956, the __ was proclaimed by the International Electro-technical Commission-Committee of Action. All MRI machines are calibrated in __

A

“Tesla Unit”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

THE STRENGTH OF A MAGNETIC FIELD IS MEASURED IN __

A

TESLA OR GAUSS UNITS.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The stronger the magnetic field, the ___ which can be elicited from the body’s atoms and therefore the higher the quality of MRI images.

A

stronger the amount of radio signals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

1 Tesla = __Gauss

A

10,000

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Low-Field MRI

A

Under .2 Tesla (2,000 Gauss)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Mid-Field MRI - __

A

.2 to 0.6 Tesla (2,000 Gauss to 6,000 Gauss)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

High-Field MRI - __

A

1.0 to 1.5 Tesla (10,000 Gauss to 15,000 Gauss)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

In 1937,__ observed the quantum phenomenon dubbed nuclear magnetic resonance (NMR).
He recognized that the atomic nuclei show their presence by absorbing or emitting radio waves when exposed to a sufficiently strong magnetic field.

A

Professor Isidor I. Rabi,

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

discovered that hydrogen signal in cancerous tissue is different from that of healthy tissue because tumors contain more water.

A

RAYMOND DAMADIAN

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

a chemist and an NMR pioneer at the State University of New York, Stony Brook, produced the first NMR image.

A

PAUL LAUTERBUR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

one of the graduate students cobbled a wearable antenna coil to monitor the hydrogen broadcast detected by the coil.

A

MIKE GOLDSMITH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

first mri exam performed on a human being.
Dr. Raymond Damadian, Dr. Larry Minkott & Dr. Michael Goldsmith.

A

JULY 3, 1977

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

ORIGINAL NAMED OF THE FIRST MRI MACHINE.

A

“INDOMITABLE”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q
  • the most visible and probably the most often discussed component of the MRI system
  • it provides the powerful static (constant strength ) magnetic field about which the nuclei precess.
A

MAGNET

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

TYPES OF MAGNETS

A

Permanent magnets, Temporary Magnets, Electro-magnets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

emit a magnetic field without the need for any external source of magnetism or electrical power.

A

Permanent magnets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

behave as magnets while attached to or close to something that emits a magnetic field, but lose this characteristic when the source of the magnetic field is removed.

A

Temporary magnets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

require electricity in order to behave as a magnet.

A

Electro-magnets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Materials for Ferromagnetism

A

Iron, Nikel, Cobalt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Materials for Paramagnetism

A

Aluminum, Tungsten, Platinum, Manganese

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Materials for Diagmagnetism

A

Copper, Silver, Mercury, Carbon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q
  • is responsible for the alignment of nuclei
    1. Solenoid electromagnets the fields is usually horizontal
    2. Permanent magnets the fields is generally vertical
  • it exerts an induction force on ferromagnetic and paramagnetic substances
A

MAGNETIC FIELD

24
Q

__ is the sum of protons in the nucleus
__ is the sum of protons and neutrons in the nucleus
An__ is electrically stable, if the number of negatively charged electrons orbiting the nucleus equals the number of positively charged protons in the nucleus.

A

Atomic number
Atomic mass number
atom

25
Q

Three types of motion are present within an atom:

A
  1. Electrons spinning on their own axis
  2. Electrons orbiting the nucleus
  3. The nucleus itself spinning about its own axis
26
Q

In addition, hydrogen has a different precessional frequency at different field strengths.
At 1.5 TESLA the precessional frequency of hydrogen is__
At 0.5 TESLA the precessional frequency of hydrogen is __

A

63.86 MH; 21.28 MHZ

27
Q

THE GYROMAGNETIC RATIO OF HYDROGEN IS ___

A

42.51 MHZ/T

28
Q

Electromagnetic radiation just lower in energy than infrared. RF used in MRI is commonly in the __

A

Radiofrequency; 10 – 100 MHZ

29
Q

is the position of each magnetic moment on the precessional path Bo.

A

Phase Coherent

30
Q

comparatively slowly gyration of the axis of a spinning body so as to trace out a cone ; caused by the application of a torque tending to change the direction of the rotation axis.
- The second spin of magnetic moment around Bo

A

Precession

31
Q

the speed of precession

A

Precessional (Larmor) Frequency

32
Q

spin, lattice, or longitudinal relaxation time
- the characteristics time constant for spins to tend to align themselves with the external magnetic fields

A

T1 Relaxation Time

33
Q
  • spin – spin, transversal relaxation time
  • spins begin to precess oit of phase with each other
A

T2 Relaxation Time

34
Q
  • If transverse magnetization of the spins is produced, a transient MR signal will result, which will decay with a characteristics time constant T2.
  • As the magnitude of transverse magnetization decreases, so does the magnitude of the voltage induced in the coil.
  • Loss of signal due to relaxation
A

Free Induction Decay (FID)

35
Q

the precessional frequency of an element at 1.0 TESLA

A

Gyromagnetic ratio

36
Q
  • denotes the direction of the north/south axis of a magnet and the amplitude of the magnetic field
A

Magnetic moment

37
Q
  • ability of a substance to become magnetized.
A

Magnetic susceptibility

38
Q
  • a property of all matter that depends on the magnetic susceptibility of the atom
A

Magnetism

39
Q

the magnetic vector produced as a result of the alignment of excess hydrogen nuclei with magnetic field.

A

Net Magnetization Vector (NMV)

40
Q
  • is a phenomenon whereby an object is exposed to an oscillating perturbation that has a frequency close to its own natural of oscillation
A

Resonance

41
Q

ATOMS THAT ARE ELECTRICALLY UNSTABLE DUE TO DEFICIT, OR AN EXCESS NUMBER OF ELECTRONS, ARE CALLED __

A

IONS.

42
Q

MRI is based on the spinning motion of a specific kind of nuclei present in biological tissues. These are called __

A

MR active nuclei

43
Q

These are characterized by their tendency to align their axis of rotation to an applied magnetic field.

A

MR ACTIVE NUCLEI

44
Q
  • it is the vector sum of the individual magnetic moments of all the protons in the nucleus
A

TOTAL MAGNETIC MOMENT

45
Q

Due to the laws of quantum mechanics only nuclei with an __ of protons have a total magnetic moment and can interact with an external magnetic field.

A

odd number

46
Q

The hydrogen nucleus contains a single proton (atomic number 1).
- It is used because it is very abundant in the human body.
- Its solitary proton gives a large magnetic moment

A

HYDROGEN NUCLEUS

47
Q
  • Low thermal energy nuclei
  • Low energy to oppose the external magnetic field.
A

PARALLEL NUCLEI

48
Q
  • High thermal energy nuclei
  • High thermal energy, do posses enough energy to oppose the strength of external magnetic field
A
  1. ANTI-PARALLEL NUCLEI
49
Q
  • The static external magnetic field is called B0
  • The interaction of the NMV with B0 the basis of MRI
  • The unit of is tesla or gauss.
A

Magnetization Vector (NMV)

50
Q
  • are loops of wire or thin conductive sheets on a cylindrical shell lying just inside the bore of an MR scanner. When current is passed through these coils a secondary magnetic field is created.
A

Gradients

51
Q

-is the generator of the radiofrequency current which is delivered to the transmitting coil. This creates a signal which is used to excite protons in the imaging field.

A

TRANSMITTER COIL

52
Q

Radiofrequency coilscan be both __ and __of the radiofrequency signal or receivers alone.
- A radiofrequency coil that performs both of these actions is called a __

A

transmitters andreceivers; transmit receiver coil or a transceiver coil.

53
Q

Acoil, or antenna, positioned within the imaging volume and connected to thereceivercircuitry that is used to detect or receive the MR signal from the patient as the disturbed spins relax back into their equilibrium distribution.

A

RECEIVER COIL

54
Q

MRIcomputercan be divided into

A

central processing unit (CPU), consisting of instruction, interpretation and arithmetic unit plus fast access memory.

55
Q

Computercontrols the __ and __ necessary to acquire data, and process the data to produce__or images.

A

RF pulses and gradient; spectra

56
Q
A
57
Q
A

MIDTERMS - 3RD YR TRANSES (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions