Application of phase regression to multi-echo BOLD

[tsalo]

@CesarCaballeroGaudes @eurunuela @idevicente have any of you tried applying phase regression to multi-echo data? Asking you three because of your connections to https://github.com/idevicente/Phase-based_denoising_pipeline.

Stems from #9 and #2.

[eurunuela]

We used single-echo data for that work. I cannot remember if Iñigo tried it on multi-echo data though.

[CesarCaballeroGaudes]

We haven't tried yet, but we have collected new multi-echo data with both magnitude and phase in several projects.

[tsalo]

The easiest thing would be to just use the echo closest to 30 ms I guess, but I wonder if there would be any benefit to either averaging the complex-valued data across echoes before running the phase regression pipeline or running the pipeline on each echo separately and then averaging the denoised magnitude data afterward.