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P2 Flashcards

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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
- USES 90°-90°- 90° - Single data are not sufficient to create an image
SATURATION RECOVERY (SR) PULSE SEQUENCE
26
time from the start of one pulse sequence to the start of the next pulse sequence.
REPETITION TIME(TR)
27
- Uses a 90° pulse followed by a 180° refocusing pulse. - Produces T1, T2, and PD weighted images.
Spin Echo (SE)
28
- Employs a single flip angle without 180° pulse. - Faster imaging with susceptibility effects.
Gradient Echo (GRE)
29
• Begins with a 180° inversion pulse. • Enhances contrast for specific tissues (e.g., STIR, FLAIR) • NO MRI SIGNAL IS CREATED.
Inversion Recovery (IR)
30
Time between successive RF pulses.
TR (Repetition Time)
31
Time from RF pulse to signal detection.
TE (Echo Time)
32
Time from inversion pulse to excitation pulse.
TI (Inversion Time)
33
: Angle by which M is tipped into the transverse plane
Flip Angle
34
- Highlights fat and soft tissues. - Used for anatomical detail.
T1-Weighted Imaging
35
- Highlights fluid and pathology. - Used for edema, tumors, and inflammation
T2-Weighted Imaging:
36
- Distinguishes between structures with different hydrogen densities.
PD-Weighted Imaging
37
- STIR for musculoskeletal imaging. - FLAIR for brain lesions.
Specialized Sequences
38
- DEFINED AS A PROCESS OF HYDROGEN NUCLEI LOSING THE ENERGY THEY ABSORBED DURING EXCITATION
RELAXATION
39
TYPES of RELAXATION
- SPIN LATTICE (T1 RECOVERY) - SPIN-SPIN (T2 DECAY)
40
- RECOVERY OF LONGITUDINAL MAGNETIZATION
SPIN LATTICE (T1 RECOVERY)
41
- THE LOSS OR DECAY OF MAGNETIZATION OF MAGNETIC MOMENT IN HYDROGEN NUCLEI IN TRANSVERSE PLANE
SPIN-SPIN RELAXATION (T2 DECAY OR T2 RELAXATION)
42
- THE METHOD OF ADJUSTING THE EXTRINSIC PARAMETERS TO ENHANCE THE CONTRAST BETWEEN DIFFERENT TISSUES ON IMAGE ON INTRINSIC CONTRAST PARAMETER
WEIGHTING
43
- EMPHASIZES THE T1 RECOVERY TIME OF TISSUES EFFECT ON THE IMAGES AND MINIMIZES T2 DECAY TIMES OF TISSUES EFFECT ON IMAGE
T1 WEIGHTING (T1W)
44
- The time it takes for 63% of phase coherence to be lost
T2 DECAY TIME
45
- USED FOR VISUALIZING PATHOLOGIES AND HIGHLIGHT THE PRESENCE OR LACK THEREOF FLUIDS
T2 WEIGHTED IMAGES
46
- FOCUSED ON THE DENSITY OF HYDROGEN PROTONS WITHIN TISSUES, PROVIDING IMAGES THAT REFLECT TRUE CONCENTRATION OF PROTONS
PROTON DENSITY WEIGHTING
47
Every nucleus has a quantity called
Spin
48
Are quantized into units of half-integer values(Spin Quantom Number)
Spins
49
Dictates many of the MR properties of a giver nuclear species
Spin quantom number
50
also indicates the limited number of ways a nucleus can spin
Spin Quantom Number
51
Is unique for each type of nucleus and must be measured for each.
Gyromagnetic Ratio
52
this is an empirically determined factor used to convert field strength to processional frequency
Gyromagnetic Ratio
53
Spin Quantom Number of 1H
1/2
54
Spin Quantom Number of 13C
1/2
55
Gyromagnetic Ratio of 1H
42.6
56
Gyromagnetic Ratio of 13C
10.7
57
Abundance of 1H
99
58
Abundance of 12C
98
59
Abundance of 13C
1.1
60
a quantity that has direction.
Vector
61
the view of someone standing next to the magnet.
Stationary Frame of Reference
62
Can be observed under the influence of a second magnetic field
Rotating Frame of Reference
63
Is simply defined as the Sum of the individual nuclear magnetic moments
Net Magnetization
64
• Strong, very short RF Pulses • Rotates net magnetization very strongly
Hard pulses
65
• Weaker, but longer RF Pulses • Rotates net magnetization slowly
SOFT PULSES
66
• Net magnetization at Z-axis which occurs if a subject is exposed to the external magnetic field for a longer period of time
EQUILIBIRUM (MZ)
67
• 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
SATURATED (MXY)
68
• 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
ON RESONANCE
69
• Different areas of the imaging volume has a range of resonant frequencies
OFF RESONANCE”

MRI (6 decks)

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