Analysis and Correction of Background Velocity Offsets in Cine Phase-Contrast Imaging Using Magnetic Field Monitoring

Daniel Giese^1,2, Maximilian Haeberlin¹, Christoph Barmet¹, Tobias Schaeffter², Klaas Paul Pruessmann¹, Sebastian Kozerke^1,2

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.