ROMEO Unwrapping

Please cite ROMEO if you use it!

This repository contains ROMEO 3D/4D unwrapping on arrays and a command line interface for MR data in NIfTI format.
A compiled command line tool is available under ROMEO (windows and linux executables; does not require a Julia installation) and otherwise, for opening NIfTI files in Julia NIfTI.jl or MriResearchTools.jl can be helpful.

Install Julia 1.9 or newer (https://julialang.org)
Copy the file romeo.jl from this repository to a convenient location. An alias for romeo as julia <path-to-file>/romeo.jl might be useful.

    $ julia <path-to-file>/romeo.jl phase.nii -m mag.nii -t [2.1,4.2,6.3] -o results

On the first run, the dependencies will be installed automatically.

For an extended explanation of the command line interface see ROMEO

using ROMEO
unwrapped = unwrap(phasedata3D; mag=magdata3D)

or via MriResearchTools:

using MriResearchTools
phase4D = readphase("Phase.nii") # 4D phase in NIfTI format
unwrapped = unwrap(phase4D; TEs=[4,8,12])

https://korbinian90.github.io/ROMEO.jl/dev

If multi-echo data is available, supplying ROMEO with multi-echo information should improve the unwrapping accuracy. The same is true for magnitude information.

If the multi-echo data contains large phase offsets (phase at echo time zero), default template unwrapping might fail. Setting the individual-unwrapping flag is a solution, as it performs spatial unwrapping for each echo instead. The computed B0 map is not corrected for remaining phase offsets.

For proper handling, the phase offsest can be removed using mcpc3ds from MriResearchTools. This works for monopolar and bipolar data, already combined or uncombined channels. However, if the phase is already "corrupted" by other coil combination algorithms, it might not be possible to estimate and remove the phase offsets.

4D data with an equal echo time for all volumes should be unwrapped as 4D for best accuracy and temporal stability. The echo times can be set to TEs=ones(size(phase,4))

In certain cases, the phase of the first echo/time-point looks differently than the rest of the acquisition, which can occur due to flow compensation of only the first echo or not having reached the steady state in fMRI. This might cause template unwrapping to fail, as the first echo is chosen as the template by default.
With the optional argument template=2, this can be changed to the second (or any other) echo/time-point.

This project is licensed under the MIT License - see the LICENSE for details