[Freesurfer] mri_convert Siemens .IMA error

Hi, I'm currently having problems converting .IMA files collected from a Siemens Skyra to .mgz format using mri_convert from Freesurfer5.3 on os x.

Using:

mri_convert -it siemens -ot mgz 1.IMA test.mgz I get the error message: does not contain a Siemens ASCII header has this file been anonymised? ERROR: cannot unpack mosiacs without ASCII header

The .IMA files have been taken straight from the scanner console.

If I try:

mri_convert -it dicom -ot mgz 1.IMA test.mgz this creates the .mgz, however there is an orientation shift and a vertical stripe artefact appears in the sagittal view (please see attached) when compared to the original .IMA.

Any suggestions on how to convert the Siemens .IMA files correctly?

Thanks, Paul