Brainmap: Taming the encoding fields in MRI – applications to spinal cord imaging- Johanna Vannesjo, PhD

Abstract

Magnetic resonance imaging crucially relies on accurate spatial and temporal magnetic field distributions for signal encoding. In the ideal situation, the background B0 field should be perfectly homogenous and stable over time, and known gradient time-courses should be added for spatial encoding of the signal. In reality, however, several factors disturb the encoding fields: i) actual gradient time-courses do not perfectly follow ideal, ii) the background field is distorted by susceptibility differences between tissue types and air, and iii) time-varying B0 fields are induced by physiological processes of the subject. These disturbances lead to artifacts that can take the form of eg ghosting, geometric distortion and signal modulation/dropout. I will here present a few strategies for addressing encoding field imperfections, with special emphasis on the relation to spinal cord imaging at ultra-high field.

About the Speaker

Johanna Vannesjo did her PhD in the group of Klaas Pruessmann at ETH Zurich, Switzerland, working on characterizing and correcting for field imperfections in MRI. Since 2014 she works as a post-doctoral fellow with Karla Miller and Irene Tracey at the FMRIB centre, University of Oxford, UK, where her research focus has shifted towards spinal cord imaging at ultra-high field.