[Insight-users] Vital DICOM information/tags when registering images?

[Patrik Brynolfsson]

Hello,
I'm working on a Matlab mex-implementation of an ITK registration. This
means that instead of loading the images from files I will load them from
memory as 3D matrices. All the DICOM information needs to be passed to ITK
from Matlab as well, and this is where my problems begin. The information
that I thought was essential for a correct registration is:

* Origin
* Spacing
* Direction

I set these using the "ChangeInformationImageFilter" and it is working; the
images have the origin, spacing and directional cosines that are assigned to
them, and they are the same as if the dicom images were loaded from files.

However, the result of the registration is different from that when loading
the images from files, with all other components set the same, (of course I
reinitialize the seed). Not by much, but they should be exactly the same! I
use Mattes mutual information metric, linear interpolation, Versor rigid 3D
transform and the accompanying Versor rigid 3D optimizer together with the
"CenteredTransformInitializer".

I know that the difference in results are due to the way I read the data. If
I change the input from memory to reading the dicom files I get the same
result as with a stand-alone .exe-application, so this is where the error
is.

Does anyone have any idea as to what other information I need to pass from
matlab to get identical results?

Thanks in advance
-- 
Patrik Brynolfsson
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