Question 1

In nuclear magnetic resonance imaging, we are interested in tissue composition.

Accepted Answer

A) True 
 B)False

Question 2

Which of the following statements is an accurate description of spin lattice relaxation time (T1)  in nuclear magnetic resonance?

Accepted Answer

A)  T1 is always larger than or equal to spin-spin relaxation time (T2) .
B)  T1 is a constant that describes the return to equilibrium of transverse magnetization.
C)  T1 is the time to reduce transverse magnetization by a factor of 
E)  
D)  T1 is the same for different samples and biological tissues.E) A) and B)
F) None of the above A

Question 3

Which of the following is NOT an accurate description of nuclear magnetic resonance (NMR) ?

Accepted Answer

A)  The energy difference between the two spin states depends on the strength of the external magnetic field.
B)  The nuclei are in resonance with electromagnetic radiation when they absorb energy.
C)  When a proton is aligned in the direction of an external magnetic field, its energy is lower than when it is aligned against the direction of an external magnetic field.
D)  The high energy radiation needed for protons to flip the spin is in the ultraviolet domain of the electromagnetic spectrum.E) C) and D)
F) None of the above

Question 4

In nuclear magnetic resonance (NMR) , what is the change that nuclei experience when they are exposed to the external magnetic field and electromagnetic radiation?

Accepted Answer

A)  All nuclei assume the direction of the external magnetic field.
B)  Some nuclei assume the direction of the external magnetic field, and some the opposite.
C)  The nuclei assume random orientations.
D)  All nuclei are oriented in the direction opposite to the external magnetic field.E) A) and C)
F) All of the above

Question 5

Biological tissues are made predominantly of 12C, 16O, 1H, and 14N. Which of these isotopes is useful for nuclear magnetic resonance?

Accepted Answer

A)  (12
C)  
B)  (16O) 
C)  (1H) 
D)  (14N) E) A) and C)
F) None of the above

Question 6

The nuclear magnetic resonance (NMR)  effect exploits the behaviour of one of these types of particles. Which type of particle is it?

Accepted Answer

A)  protons
B)  neutrons
C)  electrons
D)  photonsE) All of the above
F) B) and D)

Question 7

Briefly explain the nuclear magnetic resonance (NMR) effect.

Accepted Answer

When nuclei are placed in an external magnetic field, different spin states get different magnetic potential energies. Electromagnetic waves (radio waves) of corresponding frequencies (resonant frequencies) can be absorbed, and can induce a transition between spin energy states. After the electromagnetic radiation is removed, the nuclei relax to the lower state, and emit electromagnetic radiation of the resonant frequency associated with the spin flip.
RAT: When nuclei are placed in an external magnetic field, different spin states get different magnetic potential energies. Electromagnetic waves (radio waves) of corresponding frequencies (resonant frequencies) can be absorbed, and can induce a transition between spin energy states. After the electromagnetic radiation is removed, the nuclei relax to the lower state, and emit electromagnetic radiation of the resonant frequency associated with the spin flip.

Question 8

Which of the following does NOT describe a spin-spin relaxation time (T2)  in nuclear magnetic resonance?

Accepted Answer

A)  T2 is a constant that describes the return to equilibrium of transverse magnetization.
B)  T2 is always smaller than spin lattice relaxation time (T1) .
C)  T2 is the time to reduce transverse magnetization by a factor of 
E)  
D)  T2 is different for different samples and biological tissues.E) B) and C)
F) A) and B)

Question 9

Magnetic field gradient causes different magnetic fields at different positions and different Larmor frequencies. This frequency variation can be used to determine the location of different anatomical features during reconstruction of an image.

Accepted Answer

A) True 
 B)False

Question 10

High energy electromagnetic radiation is used to stimulate nuclei in the nuclear magnetic resonance (NMR)  effect. Which range of the electromagnetic spectrum does this energy belong to?

Accepted Answer

A)  infrared
B)  ultraviolet
C)  radio
D)  X-rayE) C) and D)
F) B) and D)

Question 11

Describe briefly the problem that arises from the use of a real magnet as opposed to an ideal magnet in NMR, and what technique helps to overcome this and make very sensitive measurements possible.

Accepted Answer

The real magnetic field is not...

Question 12

Nuclei, as dipoles with magnetic spins, all rotate in the external magnetic field's Larmor frequency.

Accepted Answer

A) True 
 B)False

Question 13

In nuclear magnetic resonance (NMR), nuclei are changing spin orientation as they occupy excited states. This is obtained by exposing nuclei only to an external magnetic field.

Accepted Answer

A) True 
 B)False

Question 14

Which of these pairs describes how a spin density-weighted signal is produced using a pulse sequence?

Accepted Answer

A)  long TE and long TR
B)  long TE and short TR
C)  short TE and long TR
D)  short TE and short TRE) A) and B)
F) A) and C)

Question 15

Describe the reasons why direct measurements of T1 and T2 are not used for magnetic resonance imaging.

Accepted Answer

Direct measurements of T1 and T2 are not...

Question 16

Which of the MRI modes is the most similar to a CT scan? What are the similarities, and what are the differences between the two?

Accepted Answer

Proton density-limited MRI is ...

Question 17

A nuclear magnetic resonance (NMR) spectrum results from the emission of photons when nuclear spin alignment is flipped.

Accepted Answer

A) True 
 B)False

Question 18

What is a physical cause of spin echo?

Accepted Answer

After the initial 90 degree pulse, spins begin to drift due to dephasing. A 180 degree pulse is now sent, flipping all the spins, which will now converge in the direction in which they were dephasing. The echo is generated by the spins returning to coherence after the 180 degree pulse.
RAT: Fig. 26.7

Question 19

Magnetization is different for various tissues. With many tissues involved in magnetic resonance imaging, we need to obtain the best possible contrast. Magnetic resonance imaging is, for this reason, done in three modes. Which of the following is NOT one of the modes?

Accepted Answer

A)  a mode that emphasizes contrast due to proton density
B)  a mode that emphasizes contrast due to photon density
C)  a mode that emphasizes contrast due to relaxation time T1
D)  a mode that emphasizes contrast due to relaxation time T2E) A) and D)
F) None of the above

Question 20

Why is the nuclear magnetic resonance (NMR) effect useful for structural analysis of human tissue?

Accepted Answer

In nuclear magnetic resonance, nuclei ar...

Exam 26: Magnetic Resonance Imaging

In nuclear magnetic resonance imaging, we are interested in tissue composition.

Correct Answer
verified

Which of the following statements is an accurate description of spin lattice relaxation time (T1) in nuclear magnetic resonance?

Correct Answer
verified
A

Which of the following is NOT an accurate description of nuclear magnetic resonance (NMR) ?

Correct Answer
verified

In nuclear magnetic resonance (NMR) , what is the change that nuclei experience when they are exposed to the external magnetic field and electromagnetic radiation?

Correct Answer
verified

Biological tissues are made predominantly of ¹²C, ¹⁶O, ¹H, and ¹⁴N. Which of these isotopes is useful for nuclear magnetic resonance?

Correct Answer
verified

The nuclear magnetic resonance (NMR) effect exploits the behaviour of one of these types of particles. Which type of particle is it?

Correct Answer
verified

Briefly explain the nuclear magnetic resonance (NMR) effect.

Which of the following does NOT describe a spin-spin relaxation time (T2) in nuclear magnetic resonance?

Correct Answer
verified

Magnetic field gradient causes different magnetic fields at different positions and different Larmor frequencies. This frequency variation can be used to determine the location of different anatomical features during reconstruction of an image.

Correct Answer
verified

High energy electromagnetic radiation is used to stimulate nuclei in the nuclear magnetic resonance (NMR) effect. Which range of the electromagnetic spectrum does this energy belong to?

Correct Answer
verified

Describe briefly the problem that arises from the use of a real magnet as opposed to an ideal magnet in NMR, and what technique helps to overcome this and make very sensitive measurements possible.

Correct Answer
verified
The real magnetic field is not...
View Answer

Nuclei, as dipoles with magnetic spins, all rotate in the external magnetic field's Larmor frequency.

Correct Answer
verified

In nuclear magnetic resonance (NMR), nuclei are changing spin orientation as they occupy excited states. This is obtained by exposing nuclei only to an external magnetic field.

Correct Answer
verified

Which of these pairs describes how a spin density-weighted signal is produced using a pulse sequence?

Correct Answer
verified

Describe the reasons why direct measurements of T1 and T2 are not used for magnetic resonance imaging.

Correct Answer
verified
Direct measurements of T1 and T2 are not...
View Answer

Which of the MRI modes is the most similar to a CT scan? What are the similarities, and what are the differences between the two?

Correct Answer
verified
Proton density-limited MRI is ...
View Answer

A nuclear magnetic resonance (NMR) spectrum results from the emission of photons when nuclear spin alignment is flipped.

Correct Answer
verified

What is a physical cause of spin echo?

Magnetization is different for various tissues. With many tissues involved in magnetic resonance imaging, we need to obtain the best possible contrast. Magnetic resonance imaging is, for this reason, done in three modes. Which of the following is NOT one of the modes?

Correct Answer
verified

Why is the nuclear magnetic resonance (NMR) effect useful for structural analysis of human tissue?

Correct Answer
verified
In nuclear magnetic resonance, nuclei ar...
View Answer

Exam 26: Magnetic Resonance Imaging

In nuclear magnetic resonance imaging, we are interested in tissue composition.

Correct AnswerverifiedShow Answer

Which of the following statements is an accurate description of spin lattice relaxation time (T1) in nuclear magnetic resonance?

Correct AnswerverifiedA

Which of the following is NOT an accurate description of nuclear magnetic resonance (NMR) ?

Correct AnswerverifiedShow Answer

In nuclear magnetic resonance (NMR) , what is the change that nuclei experience when they are exposed to the external magnetic field and electromagnetic radiation?

Correct AnswerverifiedShow Answer

Biological tissues are made predominantly of 12C, 16O, 1H, and 14N. Which of these isotopes is useful for nuclear magnetic resonance?

Correct AnswerverifiedShow Answer

The nuclear magnetic resonance (NMR) effect exploits the behaviour of one of these types of particles. Which type of particle is it?

Correct AnswerverifiedShow Answer

Briefly explain the nuclear magnetic resonance (NMR) effect.

Which of the following does NOT describe a spin-spin relaxation time (T2) in nuclear magnetic resonance?

Correct AnswerverifiedShow Answer

Magnetic field gradient causes different magnetic fields at different positions and different Larmor frequencies. This frequency variation can be used to determine the location of different anatomical features during reconstruction of an image.

Correct AnswerverifiedShow Answer

High energy electromagnetic radiation is used to stimulate nuclei in the nuclear magnetic resonance (NMR) effect. Which range of the electromagnetic spectrum does this energy belong to?

Correct AnswerverifiedShow Answer

Describe briefly the problem that arises from the use of a real magnet as opposed to an ideal magnet in NMR, and what technique helps to overcome this and make very sensitive measurements possible.

Correct AnswerverifiedThe real magnetic field is not...View AnswerShow Answer

Nuclei, as dipoles with magnetic spins, all rotate in the external magnetic field's Larmor frequency.

Correct AnswerverifiedShow Answer

In nuclear magnetic resonance (NMR), nuclei are changing spin orientation as they occupy excited states. This is obtained by exposing nuclei only to an external magnetic field.

Correct AnswerverifiedShow Answer

Which of these pairs describes how a spin density-weighted signal is produced using a pulse sequence?

Correct AnswerverifiedShow Answer

Describe the reasons why direct measurements of T1 and T2 are not used for magnetic resonance imaging.

Correct AnswerverifiedDirect measurements of T1 and T2 are not...View AnswerShow Answer

Which of the MRI modes is the most similar to a CT scan? What are the similarities, and what are the differences between the two?

Correct AnswerverifiedProton density-limited MRI is ...View AnswerShow Answer

A nuclear magnetic resonance (NMR) spectrum results from the emission of photons when nuclear spin alignment is flipped.

Correct AnswerverifiedShow Answer

What is a physical cause of spin echo?

Magnetization is different for various tissues. With many tissues involved in magnetic resonance imaging, we need to obtain the best possible contrast. Magnetic resonance imaging is, for this reason, done in three modes. Which of the following is NOT one of the modes?

Correct AnswerverifiedShow Answer

Why is the nuclear magnetic resonance (NMR) effect useful for structural analysis of human tissue?

Correct AnswerverifiedIn nuclear magnetic resonance, nuclei ar...View AnswerShow Answer

Correct Answer
verified

Correct Answer
verified
A

Correct Answer
verified

Correct Answer
verified

Biological tissues are made predominantly of ¹²C, ¹⁶O, ¹H, and ¹⁴N. Which of these isotopes is useful for nuclear magnetic resonance?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
The real magnetic field is not...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
Direct measurements of T1 and T2 are not...
View Answer

Correct Answer
verified
Proton density-limited MRI is ...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
In nuclear magnetic resonance, nuclei ar...
View Answer