[vtkusers] tool for cutting away parts of a mesh

[Sebastian Hilbert]

Hi all,

Can anyone recommend a software product that can easily and readily manipulate 
meshes in the following way ...

We are reconstructing 3D models from Dicom datasets (heart) and exports those 
as STL or VTK. This is basically volume rendering and exporting. I am looking 
for a software that can read those models and let the user cut away parts of 
the model by simply encircling a region (freehand).

Any help is appreciated.

Sebastian