Recovering or creating a large nonlinear inverse transform from an ANTs registration

[muratmaga]

@sulli419

It’s my beginner understanding that the main version of ANTs (linux) under the hood is moving both images to a “middle” common point and, as part of this process, both the forward and inverse transforms are iteratively written in tandem and that either can be called up (from RAM, temp file?). Is there a way to retrieve this “default” inverse transform in Slicer? If not, is there a way to properly invert this transform within slicer (I assume it should take some time!).

They are not moved to a middle point. Please read this: Forward and inverse warps for warping images, pointsets and Jacobians · ANTsX/ANTs Wiki · GitHub

Our SlicerANTsPy extension expose both the forward and inverse warps, if you need that. However, the registration call itself is not as customizable as the SlicerANTs extension. You want to use the antsRegistrationQuickSyN[s] for the equivalent of QuickSyN in SlicerANTs extension you are currently using.