Question

1.Which would be least useful for MRI?

A. 1- H

B. 17-O

C. 12-C

D. 23-Na

E. 31-P

2. At 1.5 T, the excess number (%) of proton spins in the low energy state over the high energy state is most likely:

a) > 10

b) 10

c) 1

d) 0.01

e) < 0.01

Answer 1

1.   The least useful for MRI is
c) 12-C
      The nuclei which has no spin and which do not have magnetic resonant effect can not be studied under MRI. The nuclei that having odd mass or atomic number or having both is very useful in MRI. The most useful are : 1-H, 13- C,15- N, 17-O , 19-F,23-Na , 27-Al ,29-Si,31-P, and 39- K.

2.   c) 1

Number of nuclear spin is related to composition of nucleus . If it is having odd mass it will have only fractional spins. If there is odd number of protons and neutrons in even mass neutron, it will have integral spin and even mass nuclei having even number of protons and neutrons will have zero spin.