Forming Mr Images
(56).jpg "Forming Mr Images")
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.
A gradient
- 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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