Martijn D. Steenwijk1, Maarten J. Versluis2, Mark A. van Buchem, Johan H C Reiber1, Andrew Webb2, Julien Milles1
1Division of Image Processing, Leiden University Medical Center, Leiden, Zuid-Holland, Netherlands; 2CJ Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, Zuid-Holland, Netherlands
The aim of this work is to evaluate the gray matter / white matter (GM/WM) contrast improvement obtained by using forward-field calculations when unwrapping MR phase images of the brain. Standard phase unwrapping methods, such as high-pass filtering, prove sub-optimal in eliminating phase wraps with high spatial frequencies. Forward-field calculations can be used to compute geometry-dependent artifact-corrected (GDAC) images in which the residual phase wrapping is reduced significantly. We applied this technique to a high-resolution T2*-weighted sequence at 7T to study its effects on GM/WM contrast. The GDAC technique results in a more favourable trade-off between unwrapping and GM/WM contrast.