[Insight-users] FEM Deformable Registration versus Demons Registration

[Lydia Ng]

Hi Corinne,

> - What is the advantage of the FEM Deformable Registration over the
> Demons Registration (at the moment I get much better results with the
> demons algorithm)?

Not being an expert in FEM - I can only provide some high-level info.

FEM should be a much more powerful mechanism, potentially allowing
multi-modality registration, the ability to define and model mechanical
property of a material and the ability to allocate node points wherever =
you
want.

Demons algorithm, on the other hand, computes the field on a fixed grid =
and
"elasticity" is added externally by Gaussian smoothing the field between
iterations. Further, you have to make sure that intensity between the =
images
is matched. I.e. pixels corresponding to the same physical point have =
the
same intensity on both images.

Having said that, demons has been successfully used for inter-subject
registration for MRI brain images. For example,

B. M. Dawant, S. L. Hartmann, J.-P. Thirion, F. Maes, D. Vandermeulen =
and P.
Demaerel, "Automatic 3-D Segmentation of Internal Structures of the Head =
in
MR Images Using a Combination of Similarity and Free-From =
Transformations:
Part I, Methodology and Validation on Normal Subjects", IEEE Trans. on
Medical Imaging, vol. 18, no. 10, pp 909-916, 1999.

Further, several groups have reported successful usage of ITK =
implementation
for the same purpose.

So depending on your application, demons might be adequate for your =
needs.

- Lydia

> -----Original Message-----
> From: Corinne Mattmann [mailto:mattmaco at ee . ethz . ch]
> Sent: Monday, December 01, 2003 9:47 AM
> To: insight-users at itk . org
> Subject: [Insight-users] FEM Deformable Registration versus Demons
> Registration
>=20
> Hi,
>=20
> I'm trying to register two 3D images with the FEMRegistrationFilter =
but
> I have some problems finding the correct parameters. Therefore my
> questions:
> - Can you give me a short summary about how the parameters are working
> or do you have any references where I can find some information about
> these parameters?
> - What is the advantage of the FEM Deformable Registration over the
> Demons Registration (at the moment I get much better results with the
> demons algorithm)?
>=20
> Thanks very much,
> Corinne
>=20
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