When is a HIDA scan most appropriately used?

A HIDA scan, or hepatobiliary iminodiacetic acid scan, is a nuclear medicine imaging technique used to evaluate the function of the liver, gallbladder, and bile ducts. The most appropriate use of a HIDA scan is in the assessment of biliary obstruction, acute cholecystitis, and postoperative biliary leaks.

When evaluating acute cholecystitis, the HIDA scan can provide valuable information about gallbladder function and the presence of inflammation. During the scan, the tracer is injected into the bloodstream and subsequently taken up by the liver, with the bile being secreted into the bile ducts. If the gallbladder does not visualize on the scan, it indicates that the gallbladder is either obstructed or inflamed, which is consistent with acute cholecystitis.

Furthermore, the HIDA scan can also evaluate for biliary obstruction by assessing the excretion of the tracer into the duodenum. In cases such as postoperative leaks or strictures, the scan helps identify if there is any disruption in the flow of bile, guiding further management.

In contrast, evaluating gallstones primarily relies on ultrasound, as it is highly sensitive for this purpose. Metastatic bone lesions would typically be