Deck 14: Principles of Magnetic Resonance Imaging

Question 1

All of the following are true regarding the gyromagnetic ratio EXCEPT

A) it is a constant.
B) it relates angular momentum and magnetic moment.
C) it is characteristic of each nuclei.
D) it relates the number of spin-up and spin-down nuclei.

Answer 1

it relates the number of spin-up and spin-down nuclei.

Question 2

The magnetic moment describes the magnetic field characteristics of the

A) neutron.
B) nucleus.
C) cell.
D) proton.

Answer 2

nucleus.

Question 3

Diamagnetic substances exhibit

A) no magnetic properties outside of the magnetic field but within an external magnetic field they are slightly repelled and have a negative magnetic susceptibility.
B) no magnetic properties outside of the magnetic field but within a magnetic field they are slightly attracted and have a positive magnetic susceptibility.
C) a strong attraction when exposed to an external magnetic field and can act as a projectile.
D) magnetic properties outside of a magnetic field but within a magnetic field the magnetism is neutralized.

Answer 3

no magnetic properties outside of the magnetic field but within an external magnetic field they are slightly repelled and have a negative magnetic susceptibility.

Question 4

All of the following are true about spin-up nuclei EXCEPT

A) they are larger in number than spin-down nuclei.
B) they align parallel to the magnetic field.
C) they are of low energy.
D) they are cancelled out by spin-down nuclei.

Question 5

T1 refers to the recovery of longitudinal magnetization.

Question 6

T2 refers to the recovery of transverse magnetization.

Question 7

Contrast is controlled by varying

A) resonance.
B) precession.
C) pulse sequences.
D) the gyromagnetic ratio.

Question 8

Ferromagnetic substances exhibit

A) no magnetic properties outside of the magnetic field but within an external magnetic field they are slightly repelled and have a negative magnetic susceptibility.
B) no magnetic properties outside of the magnetic field but within a magnetic field they are slightly attracted and have a positive magnetic susceptibility.
C) a strong attraction when exposed to an external magnetic field and can act as projectiles.
D) magnetic properties outside of a magnetic field but within a magnetic field their magnetism is neutralized.

Question 9

There is a risk of thermal injury with MRI.

Question 10

A T2-weighted image is useful for the evaluation of

A) pathology.
B) anatomy.
C) articular cartilage.
D) muscle tissue.

Question 11

In what year was the first MRI scan performed?

A) 1946
B) 1952
C) 1967
D) 1977

Question 12

When an RF pulse is applied and its energy is absorbed, the net magnetization vector moves from

A) transverse direction toward longitudinal direction.
B) parallel direction toward antiparallel direction.
C) longitudinal direction toward transverse direction.
D) antiparallel direction toward parallel direction.

Question 13

In a strong magnetic field, hydrogen atoms can align

A) perpendicular or antiperpendicular to the magnetic field.
B) parallel or antiparallel to the magnetic field.
C) oblique or antioblique to the magnetic field.
D) at random to the magnetic field.

Question 14

The most common MRI scanner used in clinical practice has a magnet strength of

A) 1.5 T.
B) 2.0 T.
C) 2.5 T.
D) 3.0 T.

Question 15

T2 is also referred to as spin-spin relaxation.

Question 16

T1 is also referred to as MXY.

Question 17

If energy is delivered to the hydrogen nuclei at a different frequency than that of the Larmor frequency of the nucleus, then

A) resonance will occur.
B) resonance will not occur.
C) it will stop any resonance.
D) precession is increased.

Question 18

Which scan parameter determines the amount of time between each initial RF pulse used to excite the protons in a given region of anatomy?

A) Free induction decay (FID)
B) Time to repetition (TR)
C) Time to echo (TE)
D) Flip angle

Question 19

Paramagnetic substances exhibit

A) no magnetic properties outside of the magnetic field but within an external magnetic field they are slightly repelled and have a negative magnetic susceptibility.
B) no magnetic properties outside of the magnetic field but within an external magnetic field they are slightly attracted and have a positive magnetic susceptibility.
C) a strong attraction when exposed to an external magnetic field and can act as projectiles.
D) magnetic properties outside of a magnetic field but within a magnetic field their magnetism is neutralized.

Question 20

Artifacts caused by anatomy "moves" can be remedied by

A) equating the phase and frequency encoding directions.
B) use of postsaturation pulses.
C) decoding the phase.
D) gating.

Question 21

Fat has a long T1 and a long T2.