DTITK tools cannot read ITK transform in the text format that have been written with ITK. It considers the transform as invalid because it tries to match "# Transform0" (with a space between '#' and 'Transform0') with the second line it reads in the transform file. ITK actually does not add this space and simply writes '#Transform0' instead [1]. This is a very simple bug to correct. To preserve backward compatibility, I have just changed the reader to be able to understand both possible lines. The writer is unchanged and still add this extra space. This is not a problem as the ITK transform reader still read the file that DTI-TK outputs correctly [2]. The file to modify is './code/geometry/Affine3D.cpp (new version attached).

[1] https://github.com/Slicer/ITK/blob/slice...
[2] https://github.com/Slicer/ITK/blob/slice...