Week 2

Question 1

According to Faraday’s law of induction, the amount of current produced in a loop of wire moving through a magnetic field is proportional to the:

a. Strength of the magnetic field
b. Resonance frequency of protons in the wire
c. Spin density of the wire
d. Length of the wire

Answer 1

a. Strength of the magnetic field

Question 2

In the Larmor Equation, B0 stands for:

Answer 2

b. Static magnetic field

Question 3

A condition whereby there are MORE spins “in line” with the magnetic field than “opposed” is known as:

a. Thermal equilibrium
b. High energy
c. Low energy
d. Excitation

Answer 3

a. Thermal equilibrium

Question 4

During thermal equilibrium, the vector that represents the “spin excess” is known as the:

Answer 4

Net magnetization vector (NMV)

Question 5

The RF pulse is applied to achieve a condition known as:

Answer 5

b. Excitation

Question 6

T1 relaxation time is defined as when:

a. 63% of the longitudinal magnetization has regrown
b. 76% of the longitudinal magnetization has regrown
c. 63% of the transverse magnetization has regrown
d. 37% of the tissue’s longitudinal magnetization has regrown

Answer 6

a. 63% of the longitudinal magnetization has regrown

Question 7

T2 relaxation time is defined as when:

a. 76% of the longitudinal magnetization has decayed
b. 37% of the tissues longitudinal magnetization has decayed
c. 63% of the longitudinal magnetization has decayed
d. 63% of the transverse magnetization has decayed

Answer 7

d. 63% of the transverse magnetization has decayed

Question 8

Images acquired with SHORT TR and TE values yield images known as?

Answer 8

T1 weighted images

Question 9

Images acquired with LONG TR and TE values yield images known as?

Answer 9

T2 weighted images

Question 10

Images acquired with LONG TR and SHORT TE values yield images known as?

Answer 10

Proton density images

Question 11

Which of the following is an extrinsic parameter?

a. T2 decay
b. Echo time
c. Proton density
d. Spin-Spin relaxation

Answer 11

b. Echo time

Question 12

Which of the following is an intrinsic parameter?

a. T2 decay
b. Echo time
c. External magnetic field
d. TR

Answer 12

a. T2 decay

Question 13

What is repetition time? (TR)

Answer 13

The duration of time between each RF pulse

Question 14

What is echo time? (TE)

Answer 14

The time interval between a RF pulse and the peak of the ensuring signal

Question 15

What are the modifiable, extrinsic parameters involved in image contrast?

Answer 15

Relaxation time (TR) and Echo time (TE)

Question 16

What are the intrinsic parameters involved in image contrast?

Answer 16

T1 relaxation, T2 decay and proton density

Question 17

T1 relaxation (spin-lattice/ longitudinal relaxation) involves the recovery of the ______ as excited protons release energy and return to the ______ of the ____

Answer 17

1. thermal equilibrium
2. longitudinal orientation
3. B0/ external field

Question 18

T2 Decay involves the ___ of ___ as interactions between protons lead to the ___ of spins

Answer 18

1. loss
2. transverse magnetism
3. dephasing

Question 19

Proton density is:

Answer 19

the number of protons per unit volume of a substance

Question 20

What is Faraday’s law?

Answer 20

B0 = kl

l= current flowing through a wire (motion)
k=  proportionality constant (quantity of charge)
B0= strength of magnetic field

Question 21

There are more protons aligned with the magnetic field . Alignment with the field produces a lower energy state.

Is the net magnetisation vector (NMV) aligned or against the external field?

Answer 21

the NMV is aligned/ in the direction of the external field.

Question 22

what is the Larmor Equation?

Answer 22

The frequency of the precession is directly proportional to the strength of the magnetic field and is defined by the Larmor Equation.

wø = γBø

wø (omega zerio) is known as either the precessional, Larmor or resonance frequency.

Gamma (γ) is the gyromagnetic ratio and is a constant unique to every atom.

Question 23

what is excitation?

Answer 23

the application of an electromagnetic radio frequency (RF) pulse to increase the energy state of a proton if the pulse is applied at the resonance frequency.

Question 24

The receiver bandwidth is related to the slope of the:

a. Frequency-encoding gradient
b. Transmitting gradient
c. Phase-encoding gradient
d. Slice-selecting gradient

Answer 24

a. Frequency-encoding gradient

Question 25

Gradient magnetic fields are used to:

Answer 25

Spatially encode the data

Question 26

Slice thickness is controlled by

Answer 26

the slope of the gradient

Question 27

The gradient that is on during the sampling of the echo is the:

Answer 27

frequency encoding gradient

Question 28

The predominant biologic effect of RF fields is:

Answer 28

Tissue heating

Question 29

The term used to describe RF absorption is:

a. Specific absorption rate (SAR)
b. Summated absorption region (SAR)
c. Susceptibility attack region (SAR)
d. Sensitive acquisition range (SAR)

Answer 29

a. Specific absorption rate (SAR)

Question 30

Areas of the body that are most sensitive to the heat (from SAR) are:

a. Vertebral bodies
b. Globes of the eyes and testicles
c. Pancreas and liver
d. Brain and spinal cord

Answer 30

b. Globes of the eyes and testicles

Question 31

Imaging centres should be separated into “Zones” including all of the following EXCEPT:

Select one:

a. Zone 1 – freely accessible to any “Level” of MR personnel
b. Zone 0 – the parking lot
c. Zone 3 – the “warm” Zone, generally the console area and the last stop before the scan room
d. Zone 4 – The “hot” Zone, the scan room itself
e. Zone 2 – the interface between Zone 1 and Zone 3

Answer 31

b. Zone 0 – the parking lot