Snapshot Field Monitoring Enables Correction of Slow Field Perturbations in High-Resolution Brain MRI

Signe Johanna Vannesjo¹, Bertram J. Wilm¹, Yolanda Duerst¹, Benjamin E. Dietrich¹, David Otto Brunner¹, Christoph Barmet¹, ², Thomas Schmid¹, Klaas P. Pruessmann¹

Breathing- and motion-related field fluctuations can affect brain imaging at 7T. The resulting artifacts can be reduced by concurrent field monitoring. However, gradient dephasing and signal decay of the field probes set limits to the image resolution. Here we assume the field perturbations to be slow, and thus a single field measurement per readout suffices for correction. It is shown that with this approach good image quality can be recovered in T2*-weighted images, that display strong ghosting when not corrected. Unlike full k-space monitoring, the approach is applicable also to high-resolution imaging.