I don’t know much about PCA on meshes but it should work too I think. The idea was about using images (labelmaps) for the PCA. I have seen same examples and references of it being done on itk so it’s possible.
This is a schema of my idea:
You can check if it makes sense to you
For my case, though, it is not very simple to define landmarks on the aorta. Maybe with vertebrae it is simpler (?)
Yes, on the vertebrae is definitely simpler