Cholescintigraphy

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 "hepatic "IDA" imaging gave rise to the more common term "HIDA scan."

Indications

Cholescintigraphy can be used for the evaluation of ^ref:

• acute cholecystitis
  • the 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: good hepatic uptake of the tracer with no evidence of excretion into the bowel at 24 hours
• 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.

Tracer dose and route of administration

After intravenous injection, IDA radiotracers are taken up by hepatocytes and then excreted into the biliary system ^ref.