How to access velocity/update field from DiffeomorphicDemonsRegistrationFilter?

I'm using DiffeomorphicDemonsRegistrationFilter for deformable registration and need to access the internal velocity /update field that the algorithm computes, not just the final displacement field.

Current code:

import SimpleITK as sitk demons = sitk.DiffeomorphicDemonsRegistrationFilter() demons.SetNumberOfIterations(300) demons.SetStandardDeviations(1.0) demons.SetMaximumUpdateStepLength(2.5) demons.SetSmoothDisplacementField(True) demons.SetSmoothUpdateField(True) displacement_field = demons.Execute(fixed_image, moving_image)

Problem:
The Execute() method returns the displacement field, but I need the stationary velocity/update field that is used internally by the diffeomorphic formulation (before the exponential map is applied).

Questions:
Is there a method to access the internal velocity/update field?