01) Basic Principles of Nuclear Magnetic Resonance
1.
The earth’s magnetic field is approximately
A) 0.05 G
B) 0.5 G
C) 5 G
D) 50 G
E) 500 G
B) 0.5 G
2.
A Tesla is equivalent to
A) 1 G
B) 10 G
C) 100 G
D) 1,000 G
E) 10,000 G
E) 10,000 G
3.
Which of the following elements would be unsuitable for magnetic resonance imaging?
A) 1H1 1H
B) 6C12 12C
C) 7N14 14N
D) 11Na23 23MNa
E) 15P31 31P
B) 6C12 12C
No nuclear magnetism for atoms with even numbers of protons and neutrons: Atoms with an even A and Z will exhibit no net nuclear magnetism. Carbon-12 has 6 neutrons and 6 protons and Calcium-40 has 20 neutrons and 20 protons. Because of proton and neutron pairing, neither atom will exhibit nuclear magnetic resonance.
4.
Which of the following tissues has the longest T1?
A) CSF
B) Muscle
C) Adipose
D) Gray matter
E) White matter
A) CSF
5.
What is the Larmor frequency of hydrogen at 3.0 Tesla?
A) 4.26 MHz
B) 42.6 MHz
C) 63.9 MHz
D) 127.8 MHz
E) 170.4 MHz
D) 127.8 MHz
6.
If the external magnetic field B0 increases from 1.5 Tesla to 3.0 Tesla, the T2 of most biological tissues would
A) Decrease significantly
B) Decrease slightly
C) Remain the same
D) Increase slightly
E) Increase significantly
C) Remain the same
7.
The definition of T1 is the time required for the longitudinal magnetization to recover what percent of its maximum value?
A) 0%
B) 37%
C) 63%
D) 95%
E) 99%
Answer
C) 63%
8.
When comparing the T1 and T2 of most biological tissues, which one of the following statements is true?
A) T1 < T2
B) T1 = T2
C) T1 > T2
D) It depends on the external magnetic strength
E) It depends on the external magnetic field homogeneity
C) T1 > T2
9.
A 90° RF pulse is applied to a tissue sample in a 1.5 Tesla magnetic field. Assuming there are no T2* effects, at a time equal to the T2 of the tissue, the amount of transverse magnetization remaining will be
A) 0%
B) 37%
C) 63%
D) 73%
E) 99%
B) 37%
10.
A 180° RF pulse is applied to a tissue sample in a 3.0 Tesla magnetic field. The resulting FID signal will
A) Not be present
B) Recover at a rate equal to T1
C) Recover at a rate equal to T2
D) Spiral down into the x-y plane and decay at a rate of T2
E) Spiral down into the x-y plane and decay at a rate of T2*
A) Not be present
FID is associated with a 90 degree pulse and decays at a rate of T2*
A 180 degree pulse has no component in the x-y plane and therefore no FID