# Forming Mr Images

12 Questions | Total Attempts: 617

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Quiz reviewing the basics of forming an MR image.

• 1.
An image creted from a slice perpendicular to the axis running from anterior to posterior in the patient is called?
• A.

Oblique

• B.

Coronal

• C.

Transverse

• D.

Sagittal

• 2.
_ is defined as a small change in the magnetic field along a particular axis.
• A.

• B.

Raw data

• C.

Digital

• D.

A fourier tansform

• 3.
In order for energy to be efficiently transferred between a transmitter and a receiver, the two must be at the same:
• A.

Charge

• B.

Frequency

• C.

Mass

• D.

Energy level

• 4.
If the field strength experienced by a patient within an MR magnet was increased, the precessional frequency of the magnetization of the patient's protons would be expected to:
• A.

Remain unaffected

• B.

Decreased

• C.

Increase

• D.

Reverse direction

• 5.
Which of the following is the function of the gradients?
• A.

They are responsible for ensuring that all of the protons in the body simultaneously receive the RF energy

• B.

They provide the energy used to move the net magnetization of the protons into the transverse plane

• C.

They casue the precessional frequency to vary with position

• D.

They stabilize the magnetic field

• 6.
If a group of protons moves toward the high end of a gradient the precessional frequency of their magnetization:
• A.

Stays the same

• B.

Increases

• C.

Decreases

• D.

Reverses directions

• 7.
The _ gradient will make the precessional frequency of the magnetization of protons in the patient's right eye different than that of the left heel.1. x 2. y 3. z
• A.

1&3

• B.

1 &2

• C.

1, 2, & 3

• D.

2 & 3

• 8.
The - gradient creates a change in the magnetic field from the patient's left side to the right side1. x2. y3. z
• A.

1 only

• B.

1 & 3

• C.

2 only

• D.

1 & 2

• 9.
In MRI, RF energy is
• A.

Transmitted to all body parts in the vicinity of the RF antenna, or coil

• B.

Collimated to strike a thin slice of protons

• C.

Shielded from striking parts of the body which are not being imaged

• D.

Focussed at a specific section of the patient's body

• 10.
If the slice though the patient that we wish to image is in a magnetic field of 0.995 T, the RF energy sould be transmitted at _ MHz.
• A.

42.85

• B.

63.9

• C.

42.39

• D.

42.6

• 11.
In order to disturb the protons in a particular location of the body, the frequency of the transmitted RF energy must be:
• A.

Matched to the precessional frequency of the magnetization produced by protons which are exposed to the same magnetic field as the magnetic field of the MR system

• B.

42.7MHz

• C.

Matched to the precessional frequency of the magnetization of protons at that particular location

• D.

63.5 MHz

• 12.
If a patient is placed in a perfectly homogeneous 1.0 T MR system in the absence of a gradient magnetic field, and an RF pulse was transmitted at 43 MHz, _ would absorbe the RF energy.
• A.

Only the protons near the patient's head

• B.

Only protons on the patient's left side

• C.

Only protons in th ecenter of the magnet

• D.

None of the protons

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