% WA4:  slice selection and k-space
%
% Problem 1:  Slice selection works by applying a gradient across the
% sample in conjunction with a pulse with limited bandwidth. If an x-gradient
% of 3.9 G/cm (39 mT/m) is applied across a sample in a 3T magnet:
%
% A) What is the resonant frequency at isocenter (Hint:  gamma =
% 42.58MHz/T) ?
%
%
% B) What is the rate of change of the magnetic field along the x-axis
% (right ear to left; hint:  gamma * G, keep an eye out for units) ?
%
%
% C) What is the rate of change of the magnetic field along the y-axis in
% the magnet (forehead to back-of-the-head)?
%
%
% D) If an RF pulse is applied with a bandwidth of 2 kHz (full width at
% half-height), what will be the thickness of the excited slice (full width
% at half-maximum)?
%
%
% E) What will the thickness of the slab be if the gradient strength is
% dropped to 0.39 G/cm (3.9 mT/m)?  What will the thickness of the slab be
% if the gradient is left at this lower strength and the bandwidth of the
% pulse is increased to 20kHz?
%
%
%
%
% Problem 2:  Two raw data matrices are provided:  kspace1.mat (or .txt)
% and kspace2.mat (or .txt).  Load these matrices and perform the 2D
% inverse Fourier transform.  What went wrong in the acquisition of the 2nd
% image?  How can this be fixed?