[Insight-users] binary deformable registration

[Siddharth Vikal]

Hello ITK users,

I've been trying to do deformable registration of two segmented binary
volumes (256x256x26). The volumes are first rigidly registered. Rigid
registration achieves me more than 80% overlap. Now I need to improve
further by correcting for shape deformation. I've tried the following:

1) FEM based deformable registration, since I have rough idea of
tissue properties (Young's modulus and Poisson's ratio) from pertinent
literature. I chose mean squares metric as Kappa/Cardinality metric
suitable for binary is not in current FEM framework; Further I chose 4
pixels/element for mesh generation. The code runs and apparently
converges but there is no real improvement in registration.

2) Kappa + BSpline transform

3) Cardinality + BSpline transform

I haven't had improvement in registration with any of above three
methods. Besides, method (2) and (3) are extremely time-consuming
(order of an hour)
Now since the organ of interest is already segmented and
rigid-registered, shouldn't it be easier to perform deformable
registration?

Please advice me.

thanks,
best regards,
siddharth