prac qs

Question 1

The nucleus of an atom has a_____ charge

Answer 1

Positive.

Presence of proton

Question 2

The electrons orbit the nucleus in regions called___

Answer 2

Electron shells or orbitals.

Question 3

Most of the mass of an atom resides in the___

Answer 3

Nucleus.

Question 4

If the atom has an equal number of protons and electrons, the atom is said to be electrically___

Answer 4

Neutral.

Question 5

Magnetism comes from the motion of charged particles inside atoms. Electrons have the property of____

Answer 5

Spin.

Question 6

When spins of the atoms cancel out each other, or when they are randomly aligned, their spin is directed at___

Answer 6

Random directions.

Question 7

Some materials like _____ have electron spins align in the same direction, creating stronger overall magnetic field.

Answer 7

Iron.

Question 8

____ refers to a fundamental property of protons related to their intrinsic angular momentum

Answer 8

Proton Spin.

Question 9

The spin of an atom is a quantum mechanical property that corresponds to literal spinning in space (T or F)

Answer 9

F.

proton spin is a form of intrinsic angular momentum, not a literal, physical rotation.

Question 10

A proton has a spin of ___

Answer 10

1/2.

Question 11

MRI observes the spin of _____ molecules in the human body using the principle of proton spin

Answer 11

Hydrogen atoms. Hydrogen nuclei.

Question 12

This describes the connection bet. The Larmor Frequency and magnetic field strength. A mathematical way to identify how a charged particle precesses in a magnetic field.

Answer 12

Larmor relationship.

Question 13

Refers to the motion of protons as they wobble around the Bo (Magnetic field) after being disturbed by the RF pulse?

Answer 13

Precession.

Question 14

This is known as the frequency of precession.

Answer 14

Larmor Frequency.

Question 15

A proton, when aligned in a magnetic field, is disturbed by____. Then, the atom releases energy at the same frequency.

Answer 15

Radiofrequency Pulse.

Question 16

MR images are made with RF in the range from approx.

Answer 16

10-300MHz.

Question 17

After a short RF pulse is applied at a specific frequency, which is called ____, which depends on the strength of magnetic field. The RF pulse tips the protons out of alignment with the Bo (magnetic field)

Answer 17

Larmor frequency.

Question 18

Refers to the uniformity and synchronization of the precessional motion of protons (or other nuclei) in response to an applied Bo

Answer 18

Phase Coherent.

Question 19

When all protons are precessing in phase, the signal they emit is weaker and more difficult to detect. (T or F)

Answer 19

F.

It is stronger and easier to detect. Bo produced by spinning atoms can add up, amplifying overall signal.

Question 20

This is the motion of nuclear spins in a Bo (magnetic field) when there is no external influence, such as RF pulse, acting on them

Answer 20

Free precession.

Question 21

For the following numbers, answer if it is phase coherent or free precession: Spins initially start in sync but lose coherence over time?

Answer 21

Free precession.

Question 22

Strong signal due to synchronized spins

Answer 22

Phase Coherent.

Question 23

Signal diminishes as spins lose phase coherence (FID)

Answer 23

Free precession.

Question 24

Spins are in sync, maintaining consistent phase.

Answer 24

Phase Coherent.

Question 25

Occurs immediately after the RF pulse, while spins are aligned

Answer 25

Phase coherent.

Question 26

Key for generating a strong initial signal

Answer 26

Phase coherent.

Question 27

Occurs after the RF pulse ends, where spins precess naturally.

Answer 27

Free precession.

Question 28

Key in measuring the decay of coherence and relaxation times (T2)

Answer 28

Free Precession.

Question 29

Time constant that describes when a signal decreases with time as the proton spins begin to lose phase coherence or diphase?

Answer 29

Relaxation time.

Question 30

Two main types of relaxation time?

Answer 30

T1 (longitudinal; Spin-lattice) and T2 (transverse; Spin-Spin).

Question 31

It refers to the time it takes for protons to return to their equilibrium state after being disturbed by RF pulse.

Answer 31

Relaxation time.

Question 32

Lattice refers to____

Answer 32

Interaction energy with the surrounding environment.

Question 33

T1 relaxation time is also known as___

Answer 33

Longitudinal relaxation time or Spin-Lattice Relaxation time.

Question 34

T1 is important for contrast between tissues in T1-weighted images. T1 short (fat) appears___. T1 long (water) appears___

Answer 34

Brighter and Darker, consecutively. ## Footnote (So FaBulous: Short, Fat, Bright) (LeWD: Long, Water, Dark)

Question 35

Other names for T2 relaxation time?

Answer 35

Transverse Relaxation Time. Spin-spin Relaxation Time.

Question 36

T2 is crucial for creating contrast in T2-weighted images where Longer T2 (water) appears____ and shorter T2 (fat) appears___

Answer 36

Brighter and Darker, consecutively. ## Footnote Reverse of LAST MNEMONICS in T1.

Question 37

Time it takes for protons to lose phase coherence in the transverse plane after the RF pulse is turned off.

Answer 37

T2.

Question 38

For the following numbers, identify if it is T1 or T2: Time for protons to lose coherence in transverse plane

Answer 38

T2.

Question 39

In Process, this is the energy exchange with surrounding lattice (tissue environment)

Answer 39

T1.

Question 40

Time for protons to realign in longitudinal plane or Bo (magnetic field)

Answer 40

T1.

Question 41

Shorter ___ (Fat) tissues are brighter. (So FaBulous)

Answer 41

T1.

Question 42

Tissues with longer___ (water) are brighter. Clue: (reverse of mnemonics: So FaBulous and LeWD)

Answer 42

T2.

Question 43

Dephasing due to interactions between spins.

Answer 43

T2.

Question 44

Generally faster

Answer 44

T2.

Question 45

Generally slower

Answer 45

T1.

Question 46

Important for showing fat vs water

Answer 46

T1.

Question 47

Important for showing edema or inflammation

Answer 47

T2.

Question 48

Term used to describe the concentration of magnetic nuclei (protons) available to contribute to the MR signal. Refers to the number of protons in a given tissue that can be detected.

Answer 48

Spin density.

Question 49

Spin density is closely related to ___

Answer 49

Proton density. ## Footnote (in MRI the signal is primarily generated by hydrogen nuclei)

Question 50

This determines the energy levels of the nucleus in an external magnetic field, which can be detected and used to gather information about the environment around the nucleus

Answer 50

Nuclear Spin.

Question 51

Spin density plays a significant role in the overall image contrast of _____

Answer 51

Proton density-weighted images (PD-weighted images).

Question 52

Muscles, in the context of proton density has___. Fat and bone, on the other hand have____.

Answer 52

Muscle: high proton density and appears brighter. ## Footnote (mas maraming available water) Fat and Bone: Low proton density and appears darker. (mas kakaunti ang water)

Question 53

Refers to the intrinsic angular momentum of an atomic nucleus. Describes a property of nucleons inside the nucleus

Answer 53

Nuclear Spin. ## Footnote It influences the behaviour of nuclei in magnetic fields.

Question 54

____ nuclei have zero nuclear spin while ___nuclei have spin value of 1/2, 1, 3/2

Answer 54

Even number and Odd number. ## Footnote Examples are (carbon-12, oxygen-16; hydrogen-1, nitrogen-15)

Question 55

Law of physic states that a spinning, charged mass induces a ___ about itself

Answer 55

Magnetic field (Bo).

Question 56

The Bo is given a special name of _____ and its intensity is related to the mass, charge, and rate of spin of the nucleus

Answer 56

Nuclear Magnetic Moment (NMM).

Question 57

This is the ratio of magnetic moment to the angular momentum of a particle; constant for a given nucleus (MHz/T)

Answer 57

Gyromagnetic Ratio.

Question 58

Non-zero spin has a _____ number of nuclei

Answer 58

odd.

Question 59

During precession, the ____ is directly proportional to the gyromagnetic ratio.

Answer 59

Frequency. ## Footnote (remember the formula)

Question 60

Formula for Gyromagnetic Ratio (Y)

Answer 60

Y= u/J (Parang YuJi**). ## Footnote Where: Y is gyromagnetic ratio, u is magnetic moment of particle, J is the angular momentum or spin of the particle.

Question 61

Hydrogen has a gyromagnetic ratio (MHz/T) of ____

Answer 61

42.6.

Question 62

Measuring the action of individual nuclei is possible (T or F)

Answer 62

F. ## Footnote Impossible, signal is a result of a bulk phenomenon from as many as 10^26 nuclei or (1000000000000000000000000000).

Question 63

The aggregate of spins (the bulk of nuclei) is sometimes called an____ to emphasize the bulk of the signal-producing nuclear spins.

Answer 63

Ensemble of spins.

Question 64

The signal from a spin ensemble accurately reflects the behaviour of each individual nuclei, and thus the ____ can be used

Answer 64

Net Magnetization (Mz) or M=∑▒〖*u〗.

Question 65

The process by which atomic nuclei are exposed to a strong magnetic field and then to a pulse of RF energy. This causes the nuclei to absorb the energy and 'resonate' at a specific frequency

Answer 65

Resonance.

Question 66

The specific frequency at which this energy is absorbed by the nuclei is called the ____, which depends on the strength of Bo and the type of nucleus.

Answer 66

Resonance Frequency.

Question 67

EMR produced by oscillator is called a

Answer 67

RF emission.

Question 68

RF oscillating electric field is positioned ____ degrees to an oscillating magnetic field

Answer 68

90.

Question 69

The RF pulse not in tuned to the nuclei's larmor frequency can be used to detect signal (T or F)

Answer 69

F. ## Footnote It must TUNED. If RF pulse is not at a specific frequency of a nuclei, the nuclei do not absorb the energy and the Mz (net magnetization) is not rotated.

Question 70

Formula for Larmor Frequency?

Answer 70

F=YBo or f=BoY (F*ck Boy). ## Footnote F= frequency of precession (MHz), Y= gyromagnetic ratio (MHz/T), Bo= is the strength of the external magnetic field (T).

Question 71

The frequency of precession of a nucleus can be calculated with the ____

Answer 71

Larmor frequency equation.

Question 72

Is a quantity that has direction

Answer 72

Vector.

Question 73

Cartesian coordinate system has a space of ____ drawn perpendicular to one another

Answer 73

X, Y, and Z.

Question 74

The parameters that affects the amplitude of the MR signal might be the ______within the sample volume

Answer 74

Number of hydrogen nuclei. ## Footnote (Recall Spin density/Proton density)

Question 75

Hydrogen has how many gyromagnetic ratio (MHz/T)?

Answer 75

42.6.

Question 76

Muscle has a relative spin density of___

Answer 76

90.

Question 77

Air has a relative spin density of

Answer 77

<1.

Question 78

Which has more spin density, muscle or bone?

Answer 78

Muscle (because of the presence of MORE hydrogen nuclei).

Question 79

After RF pulse excites the H nuclei, the nuclei release energy as they return to low-energy state. This is called?

Answer 79

Relaxation.

Question 80

The relaxation of H nuclei emit RF signals at the same frequency they absorbed when they were flipped. This is called____

Answer 80

Signal Emission.

Question 81

T1 relaxation time is parallel to ___

Answer 81

Magnetic field (Bo).

Question 82

T2 relaxation time represents the loss of net XY magnetization. Loss of phase coherence in a plane ___to Mo

Answer 82

perpendicular to or transverse.

Question 83

When nuclei are disturbed by RF pulse, the net magnetization of the atom is rotated and changed in magnitude, the nuclei realigns with the external Bo and return to equilibrium. The regrowth of net magnetization is the ____ process and represents the spin's return to equilibrium.

Answer 83

T1.

Question 84

Signal detection happening in T1 is also similar in ___ but the plane is perpendicular to or transverse to Mo, which lies along the Z-axis

Answer 84

T2.