School

Western UniversityDepartment

Medical BiophysicsCourse Code

MEDBIO 3505FProfessor

Niel GelmanStudy Guide

QuizThis

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Review Questions I for MBP3505F (Sept 21, 2017)

1) Consider an NMR signal obtained with 2 Tesla magnetic field from a phantom containing inorganic

phosphate (Pi). If the signal is given by

S(t) = S(0) exp{-(t/T2*)2} exp{-i2S'fpi t}, t t 0

S(t) = 0, t < 0

Suppose that 'fPi is the frequency shift for the Pi signal relative to the PCr frequency and that T2* = 2

ms.

a) Determine the earliest time (t > 0) at which the real part of this signal is equal to zero.

b) What is the value of the imaginary part of this signal relative to S(0) at the earliest time that the

real part is equal to zero? (i.e., at the time calculated in part a)

c) What is the value of the magnitude of the signal, relative to S(0), at t = 3 ms?

2) Suppose you acquire the 1H NMR signal from a phantom containing creatine, choline and an

unkown biochemical (in aqueous solution) in a 3 Tesla magnet. The concentration of creatine is 10

mM.

a) Assume that the unknown biochemical produces a signal component with a single frequency. If the

frequency of the signal from the unknown is 100 Hz higher than that of Creatine, what is the value

of the chemical shift for this unknown.

b) If SCh(0)/SCr(0) = 6, what is the concentration of choline? SCr(0) and SCh(0) are the signal

amplitudes at t = 0 for the CH3 protons in creatine and choline, respectively.

3) Suppose that you place three small water filled containers in the magnet of an NMR system. The

volume of water in each container is the same. One container is placed at the center of the magnet

where the magnetic field strength is exactly equal to B0. The 2nd and 3rd containers are placed at

locations where the magnetic field strengths are exactly equal to B0 + 10 PT and B0 - 10 PT (where

1 PT = 10-6 Tesla). Determine the time from the start of the NMR signal to the time at which the

signal is equal to zero. Assume that the magnetic field is uniform within each of the containers and

that the three signal components decay at the same rate (i.e, all have the same value of T2*).

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