[Insight-users] How and what the direction of image effect the registration result in ITK

[Luis Ibanez]

Hi Xi,

The direction cosines included with medical images are
essential for making sure that basic patient information
is preserved. This is as basic as knowing which side of
the patient is the Left side and which side is the Right
side.

Four percent of (reported)  medical errors in Hospitals
are still due to confusions between the left and right side
of the patient. This includes things like performing a
surgical procedure on the wrong side of the patient.
http://www.nap.edu/catalog.php?record_id=9728


It is unfortunate that Elastix has imposed this limitation
in their processing.

This restriction is unnecessary, given that ITK currently
takes the image orientation into account when computing
image registration.

You may want to contact Elastix developers
 (http://elastix.isi.uu.nl/),
maybe at the Elastix mailing list:
http://lists.bigr.nl/mailman/listinfo/elastix

and ask them why is that they imposed this restriction
in the process of image registration.


Should you decide to take the risk of replacing the
direction cosines of a medical image with an identity
matrix, you must make sure that such images are never
used for providing diagnosis or care to real patients.



      Regards,


            Luis


-------------------------------------------------------------------------
2010/2/15 Xi LIANG <liangxi1986317 at hotmail.com>:
> Dear all,
> I am using a software Elastix developed based on ITK, which asks for using
> identity direction cosine matrix to run the constraint Nonrigid registration
> properly. This means I will have to change the direction in all the original
> images. I got two suggestion on the direction issue.
> In a related post, Luis suggests that
>
> BTW: changing the direction of a medical image can
> be a dangerous thing to do. You should make sure
> that you have a good justification for replacing the
> direction of the original image.
>
> However, another ITK user suggest me to make sure all images have identity
> direction matrix before doing any further process. Therefore I am a little
> bit confused
>  here. I assume Luis and the other user concern different issues.
>
> I am not sure the meaning of the last sentence from Luis, what kind of
> issues I need to worry to get a good justification for replacing the
> direction of the original images.
>
> In order to decide whether to change the direction of the original images, I
> would like to know how and what the direction matrix would effect the
> registration result in ITK.
>
> Kind regards,
>
> --------------------------------
> Xi Liang
>
> 梁茜
> --------------------------------
>
>
>
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