lagpump,
Titanium is highly reactive with oxygen when molten, so it must be vacuum cast. Vacuum casting is only really practical with investment casting processes, and not with sand casting.
A shrouded turbine casting would probably require some coring. Some cored features can be produced with investment casting using soluble wax cores, but there are limits. The process is definitely not as flexible as sand casting in this respect.
Good luck.
Terry