Thanks guys,
maybe I had not a clear scenario of what I wanted... sorry!
Now I think the key for to do what I want is D3DImage class.
So I have to create a D3DContent like a dll and after that I have to host it in a WPF application.
I tried to build a WPF application and insert the D3DContent dll made before ( http://msdn.microsoft.com/en-us/library/cc656716.aspx and http://msdn.microsoft.com/en-us/library/cc656785.aspx).
Now I can handle the D3DImage's frame buffer like a picture in my WPF app.