Daniel Giese1,2, Maximilian Haeberlin1, Christoph Barmet1, Tobias Schaeffter2, Klaas Paul Pruessmann1, Sebastian Kozerke1,2
1Institute for Biomedical Engineering,
University and ETH
The sensitivity of phase contrast MRI to magnetic field gradient imperfections has long been recognized and a number of image-based approaches exist to partially correct for background velocity offsets. Image-based velocity offset correction assumes a sufficient number of static image pixels and often only phase offsets with 0th and 1st order in space can be accounted for. In this work, a 16-channel magnetic field camera is employed to analyze and correct background velocity offsets in cine phase-contrast velocity imaging. It is demonstrated that phase offsets exhibit primarily constant and linear terms in space but do considerably vary in magnitude over time in triggered cine sequences necessitating heart-phase dependent correction.