Hi, is there any way of using spm_coreg or other function to estimate an affine transform that includes shear rather than just the 6 parameter rigid body transform? 

I've looked at spm_affreg but this routine, as far as I can tell, can only apply a least squares cost function as opposed to the richer options in spm_coreg.

I want to register CT scan volumes which may have been acquired with gantry tilt, hence the need for a shear.

Many thanks
Mathew