• Use of radionucleotide allows some assessment of function and structure of organ.
• Technetium is injected into blood and taken up by hepatocytes before being excreted into bile.
• Used commonly in human medicine.
• Radionucleotide is transported to liver bound to albumin but the albumin-radionucleotide complexes dissociate in the liver.
• Hepatocytes take up radionucleotide via a carrier-mediated non-sodium dependent transport mechanism similar to that for bilirubin.
• The radionucleotide is secreted into the bile and transported through the biliary tract to the small intestine.

Uses

• Assessment of reticuloendothelial system function.
• Assessment of biliary tract patency and biliary kinetics.
• Evaluation of liver and spleen size and shape.
• Looking for hepatic neoplasia/metastasis.

Advantages

• Non-invasive.
• Gives information about hepatic function.

Disadvantages

• Cost.
• Limited availability.
• Radiation hazard (minimal).
• Requires patient to be isolated for a period after injection of radionucleotide.

Alternative techniques

• Biochemical assessment of hepatic function.
• Radiographic assessment of liver Radiography: abdomen or biliary tract (requires contrast study).
• Ultrasonographic examination of anatomy of liver parenchyma Ultrasonography: liver or biliary tract.

Time required

Preparation

• 5 minutes to gather equipment.
• Radionucleotide must be ordered in advance.

Procedure

• Time depends on study may last up to 4 hours but images are acquired on intermittent basis.

Decision taking

Criteria for choosing test

• Is the examination appropriate?
• Can you make the diagnosis without it?
• Will your management of the case be affected by the outcome of the examination?