New sources
of contrast are important in MRI for improving our understanding of brain
tissues and their properties. One such contrast mechanism is T2*-weighting,
created via gradient-echo imaging techniques. This form of contrast is
highly sensitive to magnetic susceptibility differences in the various
brain tissues. T2*-weighted images have the important property of showing
excellent contrast between white matter (WM) and grey matter (GM) within
the brain due to their differing susceptibilities. The phase images in
particular show fine detail previously unseen using other contrast mechanisms.
A fascinating feature of these phase images is that they give a representation
of the field-shift due to the susceptibility distribution being imaged.
My research involves exploiting the contrast properties of T2*-weighted
phase imaging to form a 3D map of the magnetic susceptibility distribution
within the brain. The major problem to be overcome is the existance
of undefined regions within k-space arising from the fourier-based technique
used to create the susceptibility maps.
