To avoid bugs, best to look at endings only
',\d+$'
otherwise, it could find this in the middle of the path for weird cases like this... "/tmp/test,1Henk/file.nii"

if doing this, you can skip Ind2

Ind1 = regexp(Fext, ',\d+$');

[fPath, fFile, fExt] = fileparts('/tmp/test,1Henk/file.nii')

fPath =

'/tmp/test,1Henk'

fFile =

'file'

fExt =

'.nii'

I don't mind replacing this, but the Fext already has the end. It could still be any weird thing right?
E.g., we would catch fExt = '.nii,1.gz'
Anyway, I don't mind much here :)

You are right. That example above will work. But I meant a weird case, but that is not likely to happen but in theory it could.

Like
[Fpath, Ffile, Fext] = fileparts('perfectlynormalifile/savedbyHenk.M.M.Mutsaerts,1April-withoutextension')
For that, we would loose a large part of the file as a supposedly SPM extension.

So my correction would be able to handle this without affecting the other functionality.

See above, we look for file endings only, so skip Ind2 and you don't need this condition again as this will never occur.

And you replace Ind2 with end