Dear Freessurfer experts,

i want to convert IMA files to nifti using mri_convert I did the following:

mri_convert 54365413.ima output.nii

I got this error

WARNING: bad orientation matrix (determinant = 0) in nifti1 file ...

... continuing.

if I run mri_info on output.nii I see 

voxel-to-ras determinant 0

ras to voxel transform:

mat = NULL!

MatrixFree: NULL mat POINTER!

How can I correctly convert IMA to nifti

Thank you for any suggestion

John