A HIDA scan with CCK is a specialized diagnostic imaging procedure that evaluates the function of the gallbladder and bile ducts. This nuclear medicine test involves injecting a small amount of a radioactive radiotracer into the bloodstream. The tracer travels through the liver and into the biliary system, including the gallbladder and bile ducts. Cholecystokinin (CCK) is then administered to assess how well the gallbladder contracts and empties its contents, providing detailed information about bile flow and gallbladder activity.
Why the Scan is Performed
The HIDA scan with CCK assesses the gallbladder’s ability to contract and release bile, helping diagnose various gastrointestinal disorders. It is useful for evaluating conditions like chronic cholecystitis, an inflammation of the gallbladder that often involves recurring pain. It also helps identify biliary dyskinesia, a functional disorder where the gallbladder doesn’t empty properly, even without gallstones. The scan can detect blockages in the bile ducts, which carry bile from the liver to the small intestine. It also assesses sphincter of Oddi dysfunction, a condition where the muscle regulating bile flow into the small intestine does not open as it should.
Getting Ready for the Scan
Patients are generally required to fast for 4 to 6 hours before the test. This fasting ensures the gallbladder is adequately filled with bile for better visualization. Patients should inform their healthcare provider about all medications, especially opioid or morphine-based pain medications, as these can interfere with accuracy and may need to be avoided for a period. Avoiding fatty foods or dairy products for about 24 hours before the scan is also recommended. Patients may drink clear liquids during the fasting period.
What Happens During the Scan
The HIDA scan procedure begins with the patient lying still on a table, typically on their back. An imaging technician will insert an intravenous (IV) line, usually into a vein in the arm or hand. Through this IV, a radioactive tracer is injected. This tracer travels through the bloodstream to the liver, where it is absorbed by bile-producing cells and then excreted into the bile ducts, flowing towards the gallbladder and small intestine.
A gamma camera is positioned over the abdomen to capture images as the tracer moves through the liver, bile ducts, and gallbladder. This initial imaging phase can take about 60 to 90 minutes.
After the gallbladder is clearly visualized and filled with the tracer, cholecystokinin (CCK) is administered through the IV. CCK is a hormone that stimulates the gallbladder to contract and release its stored bile into the small intestine. Continued imaging after the CCK infusion allows for the measurement of the gallbladder ejection fraction (GBEF), which indicates how effectively the gallbladder contracts and empties.
The CCK infusion typically lasts about 44 to 60 minutes. During the CCK administration, some patients might experience mild abdominal cramping or nausea, which are usually temporary sensations similar to the symptoms that led to the scan. The entire procedure usually takes about 90 minutes to 2 hours.
Understanding Your Results
A normal result typically shows the radioactive tracer moving freely from the liver into the gallbladder and then into the small intestine. A normal gallbladder ejection fraction (GBEF), which measures the percentage of bile ejected after CCK stimulation, is generally considered to be 35% or greater, with some protocols defining normal as 38% or higher.
An abnormally low ejection fraction, often below 35% or 38%, suggests gallbladder dysfunction, such as chronic cholecystitis or biliary dyskinesia. If the tracer does not enter the gallbladder, it can indicate a blockage of the cystic duct or acute inflammation (acute cholecystitis).
If the radiotracer is detected outside the biliary system, it might suggest a bile duct leak. Your doctor will review these findings, along with your symptoms and other test results, to determine next steps or treatment options.