Introduction

Although dual-echo field mapping can be used for many applications, more advanced B₀ mapping techniques are available depending on the use-case. Multi-echo field mapping, which makes use of more echoes, can be used to increase the accuracy of the computed field map. This can be useful for qMRI, shimming, or QSM, where the goal is to gather field information to map the susceptibility of the tissues. QSM is sensitive to small local variations, therefore a more accurate approach can be beneficial. This section also discusses fast B₀ field mapping in the context of capturing B₀ variations due to air differences generated by breathing. B₀ maps can be affected by eddy currents and a section is dedicated to their reduction.