Multi-echo fMRI

In multi-echo (ME) fMRI, data are acquired for multiple echo times, resulting in multiple time series for each voxel.

The physics of multi-echo fMRI

Multi-echo fMRI data is obtained by acquiring multiple TEs (commonly called echo times) for each MRI volume during data collection. While fMRI signal contains important neural information (termed the blood oxygen-level dependent, or BOLD signal, it also contains “noise” (termed non-BOLD signal) caused by things like participant motion and changes in breathing. Because the BOLD signal is known to decay at a set rate, collecting multiple echos allows us to assess whether components of the fMRI signal are BOLD- or non-BOLD. For a comprehensive review, see Kundu et al. (2017).

Why use multi-echo?

ME-EPI exhibits higher SNR and improves statistical power of analyses.

Resources

Journal articles

  • A review on multi-echo fMRI and its applications
  • A spreadsheet cataloguing papers using multi-echo fMRI, with information about acquisition parameters.

Videos

Sequences

  • Multi-echo sequences: who has them and how to get them.