Cholecystography (synonym: cholecystocholangiography) is a contrast-enhanced radiographic method for imaging the gallbladder and biliary system. Two primary variations of the procedure are distinguished: Oral cholecystography (gallbladder imaging) and intravenous cholecystocholangiography (imaging of the gallbladder and bile ducts). These are procedures that are performed with high radiation exposure, so the patient must be informed in detail about the risks and possible complications. Cholecystography generally precedes M-ERCP (cholangiopancreaticography by magnetic resonance imaging). In clinical practice, ERCP (“endoscopic retrograde cholangiopancreatography”) is often preferred to cholecystography because, in addition to diagnostics, therapeutic measures such as the removal of gallstones or the insertion of a stent (implant or fine wire frame to keep vessels or ducts open) can be performed. The following examinations are related to cholecystography or are variants of the classic examination:
- Oral cholecystography
- Intravenous cholecystocholangiography
- M-ERCP (cholangiopancreaticography by magnetic resonance imaging): a diagnostic method in gastroenterology that is a combined endoscopic and X-ray examination of the bile ducts and pancreas.
- Intraoperative cholecystography – Direct visualization of the biliary system during surgery.
- Postoperative cholecystography – A contrast agent is injected via an intraoperatively inserted T-drain to check for unobstructed bile flow.
- PTC (percutaneous transhepatic choleangiography)-Using a thin hollow needle, the contrast agent is injected from the outside through the skin directly into the bile ducts.
Indications (areas of application)
- Choledocholithiasis – gallstones in both the gallbladder and bile ducts.
- Inflammatory changes in the gallbladder/bile ducts.
- After surgical removal of the gallbladder to visualize the biliary system.
- Tumorous changes of the gallbladder/bile ducts
- Before gallstone disintegration by extracorporeal shock wave therapy.
- Before laparoscopic cholecystectomy (surgical removal of the gallbladder).
The procedure
The patient should be fasting on the day of the examination, while the previous day should avoid flatulent foods (legumes), fresh bread, fruits, vegetables and carbonated drinks. Before the actual cholecystography, an abdominal voiding scan is always performed to visualize the gallbladder and its surroundings or already to diagnose gallstones. Bile-permeable contrast media are usually iodine-containing contrast media. In oral cholecystography, the contrast medium is administered orally (the patient ingests the substance normally by mouth) and passes through the intestine into the blood of the V. portae to the liver. There it is fed to the liver metabolism and metabolized (metabolized). Subsequently, the metabolic product of the contrast agent returns to the intestine via the gallbladder and bile ducts and is excreted. In this way, the contrast medium does not lose its properties and allows radiographic documentation during the passage of the gallbladder. However, the density of contrast medium is very low, so that only the gallbladder can be visualized. In intravenous cholecystocholangiography, the contrast agent is injected intravenously and also enters the gallbladder. After about two hours, the gallbladder and bile ducts are optimally filled with contrast medium, so that meaningful images can be taken. Prior to this, control images are taken. Assessment of the contrasted gallbladder or biliary system focuses on the following elements:
- Dilations (dilatations)
- Stenoses (constrictions)
- Filling defects – for example, caused by gallstones.
- Obstructions (narrowing caused by other structures) – eg.B caused by tumors