Deck 30: Magnetic Resonance Imaging

Question 1

Problems associated with installing MRI units are:
1)stray radio waves.
2)weight.
3)effects on electronics.

A) 1 and 2 only
B) 1 and 3 only
C) 2 and 3 only
D) 1, 2, and 3

Answer 1

1, 2, and 3

Question 2

Gadolinium is a contrast agent used for MRI because it has paramagnetic properties. Compared with iodine contrast, it is:

A) excreted through the bowel.
B) more toxic and has more side effects.
C) less toxic and has fewer side effects.
D) similar in all aspects.

Answer 2

less toxic and has fewer side effects.

Question 3

The MRI signal is generated in the receiving antenna by:

A) Lenz's law of induction.
B) a silicon detector.
C) Newton's first law of motion.
D) Faraday's law of induction.

Answer 3

Faraday's law of induction.

Question 4

Proton density helps determine signal strength; however, it cannot be used alone because of the:

A) rate at which excited protons release energy to the environment.
B) different chemical environments of the nuclei.
C) fact that most soft tissues have similar numbers of protons.
D) influence of surrounding nuclei.

Question 5

Strong MRI signals are represented by _____ in the image.

A) black
B) light gray
C) white
D) dark gray

Question 6

There are a variety of magnet types that can be used for MRI. Resistive and superconductive magnets are both:

A) permanent magnets.
B) weak magnets.
C) electromagnets.
D) used at up to 3 tesla.

Question 7

A possible patient reaction to rapid venting of the supercooled liquid gases in a superconductive magnet into the examination room would be:

A) tachycardia.
B) bradycardia.
C) embolus.
D) asphyxiation.

Question 8

Generally MRI is considered safe; however, there are some hazards, which would include:

A) rapid echo spin.
B) local burns from wires on a patient.
C) headaches from the magnetic field.
D) spontaneous random molecular motion.

Question 9

Standard pulse sequences show blood flow with a _____ signal compared with surrounding tissues.

A) strong
B) low
C) bright
D) T2

Question 10

Spin-spin relaxation (T2) is the release of energy by excited nuclei:

A) as a result of interaction among themselves.
B) to their general environment.
C) according to their precessional frequency.
D) in relation to their resonant frequency.

Question 11

The wobbling motion of the proton when it is placed in a strong magnetic field is called:

A) frequency.
B) precession.
C) resonance.
D) a signal.

Question 12

The absorption of RF energy is referred to as:

A) frequency.
B) precession.
C) resonance.
D) proton density.

Question 13

Compared with CT image acquisition, MRI can obtain images:

A) independently in any plane.
B) only in the sagittal plane.
C) only in the coronal plane.
D) in the sagittal and coronal planes.

Question 14

Spin lattice relaxation (T1) is the release of energy by excited nuclei:

A) as a result of interaction among themselves.
B) to their general environment.
C) according to their precessional frequency.
D) in relation to their resonant frequency.

Question 15

MRI depends on interactions with:

A) electrons.
B) the nucleus.
C) soft tissue.
D) ionizing radiation.

Question 16

The rates of relaxation (T1 and T2) of a hydrogen nucleus depend on the:

A) resonant frequency.
B) chemical environment.
C) electron density.
D) signal intensity.

Question 17

Hydrogen is used for imaging in MRI because it:

A) has a large nucleus.
B) has a large precession.
C) is the most common element in the body.
D) is the only nucleus that can be imaged.

Question 18

A spin echo pulse sequence can provide which of the following weighted images?
1)T1
2)T2
3)Proton density

A) 1 and 2 only
B) 1 and 3 only
C) 2 and 3 only
D) 1, 2, and 3

Question 19

When the RF pulse is applied and the protons absorb the energy, the result is the protons orient to:

A) a plane perpendicular to the main field.
B) a plane parallel to the main field.
C) different precessional frequencies.
D) their original state in the nucleus.

Question 20

MRI has been useful for imaging many areas of the body, particularly the brain, because of:

A) the ability to see calcium deposits.
B) differentiation of gray matter from white matter.
C) new motion techniques.
D) fat suppression.

Question 21

MR spectroscopy is used to look at:

A) abdominal lesions.
B) blood flow.
C) chemical composition.
D) diffusion and perfusion.