chol-angi-o--graphy- radiographic examination of hepatic bile ducts or cystic bile duct (recording of bile duct); Types include percutaneous transhepatic cholangiography (PTC, needle into liver), endoscopic retrograde cholangiopancreatography (ERCP, diagnostic/therapeutic), primary/perioperative (during surgery), and secondary (post-drainage). It has largely replaced intravenous methods, with magnetic resonance cholangiopancreatography (MRCP) as a non-invasive alternative.