HIDA scan

Cholescintigraphy is the use of radiotracers to assess the anatomy and function of the biliary system (and the liver indirectly). Currently, this is most commonly performed with Tc-99m-IDA analogs, and "h"epatic "IDA" imaging gave rise to the more common term "HIDA scan."

After intravenous injection, IDA radiotracers are taken up by hepatocytes and then excreted into the biliary system. This then can be used for evaluation of:

• acute cholecystitis:
  • most common use is to confirm acute cholecystitis after an equivocal ultrasound study
  • if the tracer does not enter the gallbladder after a sufficient length of time, then this is compatible with obstruction of the cystic duct
• chronic cholecystitis
  • diagnosed if an adequate % of bile mixed with radiotracer does not exit the gallbladder after administration of CCK
• biliary atresia in neonates
• bile leak
  • if tracer spreads outside the biliary system, it provides direct evidence of a biliary leak
• biliary obstruction
  • tracer dose is held up before it can progress into the duodenum
• confirmation of biliary dilatation
  • may be useful in imaging choledochal cysts
• sphincter of Oddi dysfunction

With the exception of biliary atresia (and possibly chronic cholecystitis), cholescintigraphy is rarely a first line imaging modality but is often used as a problem-solving tool.