[vtkusers] how to extract connective fields of an isosurface?

[yawn at 263.net]

Hi, everyone:
    I read CT slices with vtkVolume16Reader and got an isosurface involving all bones by using vtkMarchingCubes. Now, I want to control each of the bones separately. In other words, I have to extract all the connective fields out of the isosurface i got. Does any vtk classes support such operations?
    I'm a newbie to vtk, and will be very appreciate of any suggestions.
                                                   
                                                          Dai Shuo