MRI

Question 1

What is spin also known as?

Answer 1

angular momentum

Question 2

What is angular momentum also known as?

Answer 2

spin

Question 3

What greek letter is this: γ

Answer 3

gamma

Question 4

What does γ mean in MRI?

Answer 4

gyromagnetic constant

Question 5

What occurs to the spin of protons when a magnetic field is applied?

Answer 5

The spins will align and spin either up or down in relation to the field

Question 6

Why aren’t all protons in the low energy alignment when in a magnetic field

Answer 6

thermal energy bounces them between states

Question 7

How can we change the spin state of protons?

Answer 7

Hit them with a photon that has the right amount of energy to increase them to the higher energy state

Question 8

What greek letter is this: ω

Answer 8

omega

Question 9

What does ω mean in MRI?

Answer 9

Larmor frequency

Question 10

What is the symbol for the Larmor Frequency

Answer 10

ω

Question 11

What is the Larmor frequency

Answer 11

rate of precession of the magnetic moment of the proton around the external magnetic field. The frequency of precession is related to the strength of the magnetic field,

Question 12

What is the Larmour equation?

Answer 12

ω = γB

B is magnetic field strength

Question 13

What’s the name of the distribution of proton energy levels due to thermodynamics in nuclear resonance?

Answer 13

The Boltzmann distribution

Question 14

FID acronym in MRI?

Answer 14

Free induction decay

Question 15

What’s it called when protons are precessing in synchronicity?

Answer 15

phase coherence

Question 16

What is Free Induction Decay in MRI

Answer 16

How quickly the signal of the precessing protons decreases after ceasing the radiofrequency burst

Question 17

What is T2 known as?

Answer 17

transverse relaxation rate

spin-spin relaxation rate

Question 18

What is T1 also known as?

Answer 18

longitudinal relaxation rate

spin-lattice relaxation rate

Question 19

What is the relation of Free Induction Decay and T2?

Answer 19

FID is made up of the T2 relaxation rate and T2 star

Question 20

What is T2 STAR?

Answer 20

The component of FID not due to true T2 relaxation, but due to phase incoherence of the protons

Question 21

What is the infomartion that needs to be known about each cos/ sine wave that makes up an image in MRI?

Answer 21

spatial frequency

magnitude

orientation

phase

Question 22

are the higher or lower frequency waves represented near the middle of k-space?

Answer 22

lower frequency (longer waves)

Question 23

In what order do the gradient encodings occur in MRI acquisition?

Answer 23

slice selection

phase encoding

frequency encoding

Question 24

When does slice selection encoding occur in MRI encoding?

Answer 24

at the same time as the RF pulses are initially emitted

Question 25

When does phase encoding occur in MRI encoding?

Answer 25

between the 2 different bursts of RF emissions (after 90 degree flip but before 180 degree flip)

Question 26

When does frequency encoding occur in MRI encoding?

Answer 26

during the acquisition portion, when the echo is being re-emitted by different parts