A cholangiogram is a medical imaging procedure used to visualize the bile ducts, which transport bile from the liver to the gallbladder and small intestine. It can be performed using X-rays after injecting a contrast dye into the bile ducts, or through non-invasive techniques like MRI or CT scans. Cholangiograms help diagnose conditions such as bile duct obstruction, stones, or tumors. They are often used during procedures like endoscopic retrograde cholangiopancreatography (ERCP) to guide treatment.