Comprehensive MRI Questions & Answers
Which of the following is NOT an essential part of localizing the MR signal generated during
an MR study?
a. moving the patient within the magnet to ensure only the center slice is imaged
b. using the FT to separate the phase and frequency components corresponding to each point
of anatomy in the image plane
c. transmitting a selective range of radio frequencies
d. applying linear gradients along the three dimensions of the magnet
a.
A given MR system claims its maximum gradient amplitude is 30 mT/meter. Imagine an ideal
case in which the field strength at all points inside the magnet is 1.500T. If a pulse sequence
drives the x-gradient to its maximum amplitude, the field strength at a point which is
centered along the x-direction and displaced one meter toward the positive direction is ____
Tesla.
a. 1.510
b. 1.490
c. 1.600
d. 1.500
d.
If a population of protons moves through some distance during the time the 90 RF pulse is
applied, what will be the appearance of the resulting image, providing that the gradients are
operating properly for a simple spin-echo pulse sequence?
a. artifacts will appear in the phase encoding direction
b. artifacts will appear in the frequency encoding direction
c. image is unaffected
d. image will be inverted
a.
Which gradient will make the precessional frequency of the magnetization of protons in the
patient's left eye different than that in the patient's right heel?
a. x
,b. y
c. z
d. z, y or the z
c.
In an ideal 1.0T magnet with perfect homogeneity, if a proton experiences a magnetic field of
1.006 T and is positioned 0.5 meters along the positive z-direction and cenetered along the x
and y-directions, the z-gradient amplitude is ____ mT/m.
a. 3
b. 6
c. 9
d. 12
d.
1.006= 1 T + (X x 0.5)/1000
Plug in options to equal out
In an ideal 1.5T magnet with perfect homogeneity, if a proton experiences a magnetic field of
1.504T and the x-gradient amplitude is 16mT/m, the displacement of the proton along the x-
direction is ____cm.
a. 25
b. 50
c. 64
d. 75
a.
B=B0+ (D x G)/1000
1.504= 1.5 + (16 x X)/1000
/100 (m -> cm)
Plug in options
,What condition must be met in order to maintain virtually zero resistance in a
superconducting magnet?
a. the superconducting windings must be maintained at a temperature approaching absolute
zero
b. there must be at least 25 turns of the superconducting windings
c. the magnetized ceramic bricks must be oriented so that their magnetic fields face in the
same direction
d. the magnet room must have air conditioning
a.
If a voltage source was connected to a solenoid, so that the current flowed as in the diagram
below, how would a magnetic field be generated?
a. to the left
b. no magnetic field would be generated
c. in the same direction as the current is flowing
d. to the right
(post test 3; page 8)
d.
The purpose of the shims is to:
a. keep RF energy used in scanning from interfering with the external enviroment
b. contain the magnetic field
c. linearly vary the magnetic field along the axis of the magnet
d. make the main magnetic field more uniform
d.
The purpose of the magnetic shielding is to:
a. linearly vary the magnetic field along
b. keep the RF energy used in scanning from interfering with the external environment
c. keep the stray radio signals in the environment from creating artifacts in the MR images
d. keep the fringe field magnetic field closer to the magnet
b.
, The correct location of the z-gradient coils in a superconductive MRI system is wrapped ____ a
cylinder within the bore of the magnet.
a. in a spiral fashion around
b. completely around each end of
c. on the top and bottom of
b.
Which of the following is affected by the transmitter bandwidth?
a. FOV of the image
b. severity of chemical shift artifact in the image
b. orientation of the image
d. the slice thickness
b.
Which of the following MRI system components is responsible for the timing and correct
performance of each component once the sequence has been started?
a. MR controller
b. pulse sequence controller
c. host computer
b.
Which of the following describes the operational mechanism of an electromagnet?
a. magnetized ceramic bricks are stacked together so that their magnetic fields point in the
same direction, generating a strong magnetic field
b. a population of small magnets wobbles at a specific frequency, generating a strong
magnetic field
c. a power supply is connected to the ends of a coil of long wire, generating a strong magnetic
field
c.
An RF pulse of what flip angle will maximize the component of the net magnetization
projected into the transverse plane?
a. 180
Which of the following is NOT an essential part of localizing the MR signal generated during
an MR study?
a. moving the patient within the magnet to ensure only the center slice is imaged
b. using the FT to separate the phase and frequency components corresponding to each point
of anatomy in the image plane
c. transmitting a selective range of radio frequencies
d. applying linear gradients along the three dimensions of the magnet
a.
A given MR system claims its maximum gradient amplitude is 30 mT/meter. Imagine an ideal
case in which the field strength at all points inside the magnet is 1.500T. If a pulse sequence
drives the x-gradient to its maximum amplitude, the field strength at a point which is
centered along the x-direction and displaced one meter toward the positive direction is ____
Tesla.
a. 1.510
b. 1.490
c. 1.600
d. 1.500
d.
If a population of protons moves through some distance during the time the 90 RF pulse is
applied, what will be the appearance of the resulting image, providing that the gradients are
operating properly for a simple spin-echo pulse sequence?
a. artifacts will appear in the phase encoding direction
b. artifacts will appear in the frequency encoding direction
c. image is unaffected
d. image will be inverted
a.
Which gradient will make the precessional frequency of the magnetization of protons in the
patient's left eye different than that in the patient's right heel?
a. x
,b. y
c. z
d. z, y or the z
c.
In an ideal 1.0T magnet with perfect homogeneity, if a proton experiences a magnetic field of
1.006 T and is positioned 0.5 meters along the positive z-direction and cenetered along the x
and y-directions, the z-gradient amplitude is ____ mT/m.
a. 3
b. 6
c. 9
d. 12
d.
1.006= 1 T + (X x 0.5)/1000
Plug in options to equal out
In an ideal 1.5T magnet with perfect homogeneity, if a proton experiences a magnetic field of
1.504T and the x-gradient amplitude is 16mT/m, the displacement of the proton along the x-
direction is ____cm.
a. 25
b. 50
c. 64
d. 75
a.
B=B0+ (D x G)/1000
1.504= 1.5 + (16 x X)/1000
/100 (m -> cm)
Plug in options
,What condition must be met in order to maintain virtually zero resistance in a
superconducting magnet?
a. the superconducting windings must be maintained at a temperature approaching absolute
zero
b. there must be at least 25 turns of the superconducting windings
c. the magnetized ceramic bricks must be oriented so that their magnetic fields face in the
same direction
d. the magnet room must have air conditioning
a.
If a voltage source was connected to a solenoid, so that the current flowed as in the diagram
below, how would a magnetic field be generated?
a. to the left
b. no magnetic field would be generated
c. in the same direction as the current is flowing
d. to the right
(post test 3; page 8)
d.
The purpose of the shims is to:
a. keep RF energy used in scanning from interfering with the external enviroment
b. contain the magnetic field
c. linearly vary the magnetic field along the axis of the magnet
d. make the main magnetic field more uniform
d.
The purpose of the magnetic shielding is to:
a. linearly vary the magnetic field along
b. keep the RF energy used in scanning from interfering with the external environment
c. keep the stray radio signals in the environment from creating artifacts in the MR images
d. keep the fringe field magnetic field closer to the magnet
b.
, The correct location of the z-gradient coils in a superconductive MRI system is wrapped ____ a
cylinder within the bore of the magnet.
a. in a spiral fashion around
b. completely around each end of
c. on the top and bottom of
b.
Which of the following is affected by the transmitter bandwidth?
a. FOV of the image
b. severity of chemical shift artifact in the image
b. orientation of the image
d. the slice thickness
b.
Which of the following MRI system components is responsible for the timing and correct
performance of each component once the sequence has been started?
a. MR controller
b. pulse sequence controller
c. host computer
b.
Which of the following describes the operational mechanism of an electromagnet?
a. magnetized ceramic bricks are stacked together so that their magnetic fields point in the
same direction, generating a strong magnetic field
b. a population of small magnets wobbles at a specific frequency, generating a strong
magnetic field
c. a power supply is connected to the ends of a coil of long wire, generating a strong magnetic
field
c.
An RF pulse of what flip angle will maximize the component of the net magnetization
projected into the transverse plane?
a. 180
