Cholescintigraphy

Cholescintigraphy

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A HIDA scan showing normal bile flow.

Cholescintigraphy, also known as a Hepatobiliary Iminodiacetic Acid (HIDA) scan, is a diagnostic imaging procedure used to evaluate the health and function of the gallbladder and the biliary tract. This nuclear medicine test involves the intravenous injection of a radioactive tracer, which is taken up by the liver and excreted into the bile. The movement of the tracer is then tracked using a gamma camera to assess the function of the gallbladder and the patency of the bile ducts.

Procedure

The procedure begins with the intravenous administration of a radiopharmaceutical agent, typically a technetium-99m labeled iminodiacetic acid derivative. The patient is positioned under a gamma camera, which captures images of the tracer as it moves through the liver, gallbladder, bile ducts, and into the small intestine.

The test is often performed over a period of 1 to 2 hours, during which time the patient may be asked to change positions to facilitate imaging. In some cases, a hormone called cholecystokinin (CCK) may be administered to stimulate gallbladder contraction, allowing for the assessment of gallbladder ejection fraction.

Indications

Cholescintigraphy is primarily used to diagnose conditions such as:

• Acute cholecystitis: Inflammation of the gallbladder, often due to gallstones.
• Chronic cholecystitis: Long-term inflammation of the gallbladder.
• Biliary atresia: A condition in infants where bile ducts are blocked or absent.
• Bile leak: Leakage of bile from the biliary system, often after surgery.
• Biliary dyskinesia: Abnormal motility of the gallbladder.

Interpretation

The results of a cholescintigraphy scan are interpreted by a nuclear medicine specialist. Normal results show the tracer moving from the liver into the gallbladder and then into the small intestine. Abnormal results may indicate:

• Non-visualization of the gallbladder, suggesting acute cholecystitis.
• Delayed tracer uptake, indicating chronic cholecystitis or biliary obstruction.
• Absence of tracer in the small intestine, suggesting a bile duct obstruction.

Advantages and Limitations

Cholescintigraphy is a non-invasive and highly sensitive test for detecting gallbladder and biliary tract disorders. It provides functional information that other imaging modalities, such as ultrasound or CT scan, may not offer.

However, the test has limitations, including:

• Exposure to a small amount of radiation.
• Potential for allergic reactions to the radiopharmaceutical.
• Limited anatomical detail compared to other imaging techniques.

Related pages

• Gallbladder disease
• Biliary tract
• Nuclear medicine
• Radiopharmaceutical