FAQ

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  When encountering an error or bug in Gannet, please first check you are using the latest version. It may be that your issue has already been addressed.

If your issue has not been addressed or is not found in this FAQ, please report the issue to us on GitHub or the MRSHub Forum.

General

1. Can Gannet process non-edited data?

No, Gannet is designed to process edited single-voxel data only. However, the standalone tool CoRegStandAlone can be used with non-edited single-voxel data to co-register voxels to structural images and segment the images to obtain voxel tissue fractions.

2. Can Gannet process MRSI data?

No.

3. Can Gannet process GSH-edited data?

Yes, Gannet can process GABA-, GSH-, Lac-, and EtOH-edited MEGA-PRESS data, as well as GABA-/GSH-, Lac-/GSH-, and EtOH-/GABA-/GSH-edited HERMES and HERCULES data. (Fitting of HERCULES phantom data is not supported, however.) Simply set the appropriate target option(s) in GannetPreInitialise.m.

4. Can Gannet process HERMES/HERCULES data?

GannetLoad.m can load and preprocess HERMES and HERCULES data, but only HERMES data can be modeled in GannetFit.m. HERCULES data can be fully processed and fitted using the Osprey software package.

5. Can Gannet process phantom data?

Yes, Gannet can process and fit phantom edited data as described above. Make sure to set phantom to 1 under Flags in GannetPreInitialise.m. If you want to fit your data, run GannetFitPhantom(MRS_struct); instead of GannetFit(MRS_struct);. (Fitting of HERCULES phantom data is not supported.)

Output

1. Why is my spectrum upside down?

Gannet has a routine that automatically phases spectra so that they are not upside-down or otherwise out of phase. However, this routine can fail. It is best to contact the developers for assistance to resolve the problem. A possible, but not infallible, solution is to add the following line of code to GannetLoad.m after the function PhaseCorrection.m is run for global zero-order phase correction (around line 400):

MRS_struct.fids.data = -MRS_struct.fids.data;

Errors

1. You have issues with SPM MEX files on macOS Catalina, Big Sur, Monterey, Ventura

Specifically:

"*.mexmaci64" cannot be opened because the developer cannot be verified. macOS cannot verify that this app is free from malware.

or

Code signature not valid for use in process using Library Validation: library load disallowed by system policy.

Please visit the SPM Wikibooks page for troubleshooting.

2. MATLAB says my structural image does not exist

For example:

Error using spm_vol>spm_vol_hdr (line 80)
File “image1.nii” does not exist.

Error in spm_vol (line 61)
** v = spm_vol_hdr(deblank(P(i,:)));**

Error in GannetMask_SiemensTWIX (line 110)
V = spm_vol(nii_file);

Error in GannetCoRegister (line 74)
** MRS_struct = GannetMask_SiemensTWIX(fname, nii_name{ii}, MRS_struct, ii, vox, kk);**

Error in gannetcode (line 19)
** MRS_struct = GannetCoRegister(MRS_struct,{‘image1.nii’});**

A possible fix for this is to input filenames using their full path. So, instead of {'image1.nii'}, input {'/Users/username/Documents/my_project/data/image1.nii'}.

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