When hepatic biliary radicals are dilated in a ct scan, what exactly does it mean?

There's a blockage : By "radicals" i assume you mean ducts. When a duct (pipe) is dilated it means it's enlarged. Imagine a stretchy soft pipe that normally drains liquid. If something blocks it, the back end will enlarge. The most common things that cause a dilated biliary duct are stones.:).

Can be: Bile duct blockage. See gastroenterologist or general surgeon.