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MRI > P2 > Flashcards

P2 Flashcards

1
Q

the branch of physics that describes the behavior of large objects such as rockets, automobiles, and Ping-Pong balls.

A

Classical mechanics

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2
Q

the branch of physics that describes the behavior of very small objects, such as x-rays, protons, neutrons, and electrons.

A

Quantum mechanics

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3
Q

has one proton and one electron and behaves like a bar magnet.

A

Hydrogen

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4
Q

▪ In an MRI machine, an ____ influences hydrogen atoms, aligning their orientation into parallel (more) or anti- parallel (less). Produces a net magnetization vector (Mz) along the z-axis (longitudinal).

A

External Magnetic Field (B0)

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5
Q

Each proton spins on its axis like a spinning
top, a motion called ____

A

precession

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6
Q

Speed of precession

A

Frequency

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7
Q

The speed of precession (frequency) depends on the strength of the magnetic field (B0) and is defined by the ____

A

Larmor Equation

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8
Q

: Time for nuclei to realign with the magnetic field (63% recovery).

A

T1 Relaxation

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9
Q

: Time for nuclei to lose coherence with each other (63% lost).

A

T2 Relaxation

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10
Q

CHARGED PARTICLE ROTATING AROUND ITS OWN AXIS WITH ANGULAR MOMENT

A

CLASSICAL MODEL

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11
Q

▪ DESCRIBES HOW THE PARTICLES REACTS TO EXTERNAL MAGNETIC FIELD

A

QUANTUM MECHANICAL MODEL

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12
Q

According to quantum mechanics, every
nucleus has a quantity called ____

A

spin

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13
Q

▪ is the ratio of magnetic moment of the
particle to its angular momentum.

A

Gyromagnetic ratio

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14
Q

The exact frequency of precession by such a nucleus can be calculated with the ___

A

Larmor equation

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15
Q

IS THE SUM OF ALL THE PROTONS MAGNETIC MOMENT, THUS CALCULATE THE MRI SIGNAL

A

NET MAGNETIZATION VECTOR

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16
Q

In MRI, the main magnetic field is termed ____

A

B0

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17
Q
  • a phenomenon that occurs when an object is exposed to an oscillating perturbation that has a frequency close to its own natural frequency of oscillation
A

RESONANCE

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18
Q
  • Measures the signal of the coil that is
    transverse to our magnetic field
A

FLIP ANGLE

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19
Q

are patterns of radiofrequency energy used to manipulate the net magnetization of hydrogen nuclei in
MRI.

A

RF pulse sequences

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20
Q

Determines image contrast, signal strength,
and diagnostic capability.

A

RF pulse sequences

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21
Q

Alignment of hydrogen nuclei in a magnetic field (B0).

A

Net Magnetization (M)

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22
Q

Movement of nuclear spins
around the magnetic field.

A

Precession

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23
Q

: Energy absorption by nuclei at
the Larmor frequency.

A

Resonance

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24
Q

TYPES OF PULSE SEQUENCE

A
  • ONE-PULSE
  • TWO-PULSE
  • MULTI-PULSE
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25
Q
  • USES 90°-90°- 90°
  • Single data are not sufficient to create an
    image
A

SATURATION RECOVERY (SR) PULSE
SEQUENCE

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26
Q

time from the start of one pulse sequence to the start of the next pulse sequence.

A

REPETITION TIME(TR)

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27
Q
  • Uses a 90° pulse followed by a 180°
    refocusing pulse.
  • Produces T1, T2, and PD weighted images.
A

Spin Echo (SE)

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28
Q
  • Employs a single flip angle without 180°
    pulse.
  • Faster imaging with susceptibility effects.
A

Gradient Echo (GRE)

29
Q

• Begins with a 180° inversion pulse.
• Enhances contrast for specific tissues (e.g., STIR, FLAIR)
• NO MRI SIGNAL IS CREATED.

A

Inversion Recovery (IR)

30
Q

Time between successive RF pulses.

A

TR (Repetition Time)

31
Q

Time from RF pulse to signal detection.

A

TE (Echo Time)

32
Q

Time from inversion pulse to excitation pulse.

A

TI (Inversion Time)

33
Q

: Angle by which M is tipped into the transverse plane

A

Flip Angle

34
Q
  • Highlights fat and soft tissues.
  • Used for anatomical detail.
A

T1-Weighted Imaging

35
Q
  • Highlights fluid and pathology.
  • Used for edema, tumors, and inflammation
A

T2-Weighted Imaging:

36
Q
  • Distinguishes between structures with
    different hydrogen densities.
A

PD-Weighted Imaging

37
Q
  • STIR for musculoskeletal imaging.
  • FLAIR for brain lesions.
A

Specialized Sequences

38
Q
  • DEFINED AS A PROCESS OF HYDROGEN
    NUCLEI LOSING THE ENERGY THEY
    ABSORBED DURING EXCITATION
A

RELAXATION

39
Q

TYPES of RELAXATION

A
  • SPIN LATTICE (T1 RECOVERY)
  • SPIN-SPIN (T2 DECAY)
40
Q
  • RECOVERY OF LONGITUDINAL
    MAGNETIZATION
A

SPIN LATTICE (T1 RECOVERY)

41
Q
  • THE LOSS OR DECAY OF MAGNETIZATION OF MAGNETIC MOMENT IN HYDROGEN NUCLEI IN TRANSVERSE PLANE
A

SPIN-SPIN RELAXATION (T2 DECAY OR T2
RELAXATION)

42
Q
  • THE METHOD OF ADJUSTING THE EXTRINSIC PARAMETERS TO ENHANCE THE CONTRAST BETWEEN DIFFERENT TISSUES ON IMAGE ON INTRINSIC CONTRAST PARAMETER
A

WEIGHTING

43
Q
  • EMPHASIZES THE T1 RECOVERY TIME OF
    TISSUES EFFECT ON THE IMAGES AND
    MINIMIZES T2 DECAY TIMES OF TISSUES
    EFFECT ON IMAGE
A

T1 WEIGHTING (T1W)

44
Q
  • The time it takes for 63% of phase coherence to be lost
A

T2 DECAY TIME

45
Q
  • USED FOR VISUALIZING PATHOLOGIES AND HIGHLIGHT THE PRESENCE OR LACK
    THEREOF FLUIDS
A

T2 WEIGHTED IMAGES

46
Q
  • FOCUSED ON THE DENSITY OF HYDROGEN PROTONS WITHIN TISSUES, PROVIDING IMAGES THAT REFLECT TRUE
    CONCENTRATION OF PROTONS
A

PROTON DENSITY WEIGHTING

47
Q

Every nucleus has a quantity called

A

Spin

48
Q

Are quantized into units of half-integer values(Spin Quantom Number)

A

Spins

49
Q

Dictates many of the MR properties of a giver nuclear species

A

Spin quantom number

50
Q

also indicates the limited number of
ways a nucleus can spin

A

Spin Quantom Number

51
Q

Is unique for each type of nucleus and must be measured for each.

A

Gyromagnetic Ratio

52
Q

this is an empirically determined factor used to convert field strength to processional frequency

A

Gyromagnetic Ratio

53
Q

Spin Quantom Number of 1H

A

1/2

54
Q

Spin Quantom Number of 13C

A

1/2

55
Q

Gyromagnetic Ratio of 1H

A

42.6

56
Q

Gyromagnetic Ratio of 13C

A

10.7

57
Q

Abundance of 1H

A

99

58
Q

Abundance of 12C

A

98

59
Q

Abundance of 13C

A

1.1

60
Q

a quantity that has direction.

A

Vector

61
Q

the view of someone standing
next to the magnet.

A

Stationary Frame of Reference

62
Q

Can be observed under the influence of a second magnetic field

A

Rotating Frame of Reference

63
Q

Is simply defined as the Sum of the individual nuclear magnetic moments

A

Net Magnetization

64
Q

• Strong, very short RF Pulses
• Rotates net magnetization very
strongly

A

Hard pulses

65
Q

• Weaker, but longer RF Pulses
• Rotates net magnetization slowly

A

SOFT PULSES

66
Q

• Net magnetization at Z-axis
which occurs if a subject is
exposed to the external
magnetic field for a longer
period of time

A

EQUILIBIRUM (MZ)

67
Q

• An occurrence in where net
magnetization in the z-axis is
equal to zero and the net
magnetization vector is fully
transferred/observable in the
XY-Axis

A

SATURATED (MXY)

68
Q

• Describes the net magnetization
in processing in sync
• Very rarely happens (Close to
impossible) as there is no such
thing as a purely uniform
magnetic field

A

ON RESONANCE

69
Q

• Different areas of the imaging
volume has a range of resonant
frequencies

A

OFF RESONANCE”

MRI (3 decks)

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