II. Indications
- Acute Cholecystitis
- Biliary Diskinesia
- Acalculous Cholecystitis
III. Mechanism: Visualization of biliary tree (liver and gallbladder function)
- Hepatobiliary Iminodiacetic Acid (IDA) is normally taken up by the liver and excreted into the bile
- When tagged with Technetium-99, IDA can be visualized with a gamma camera
IV. Preparations: Technetium-99 Tracers
- HIDA Scan (Hydroxy-Iminodiacetic Acid)
- Replaced with other tracing agents (although scan still referred to as HIDA)
- Previously Serum Bilirubin determined the agent used (HIDA was used if Total Bilirubin <5-7 mg/dl)
- DISIDA Scan (Diisopropyl Iminodiacetic Acid)
- PIPIDA Scan (Paraisopropyl Iminodiacetic Acid)
- BrIDA Scan (bromo-2, 4,6-trimethylacetanilido Iminodiaceticacid)
V. Technique
- HIDA Scan (or DISIDA, PIPIDA or BrIDA Scan)
- Technetium-iminodiacetic acid analog injected IV (see preparations above)
- Technetium-iminodiacetic acid analog is absorbed and secreted into biliary tract by hepatocytes
- Cholecystokinin-HIDA Scan
- HIDA Scan is performed before and after Cholecystokinin (CCK) administration
- Cholecystokinin stimulates gallbladder contraction
- Assessment of gallbladder contractility and ejection fraction
- Symptoms reproduced with Cholecystokinin (CCK) injection are suggestive of Biliary Colic
VI. Interpretation
- Normal Billiary tract and Gallbladder
- Clear outline gallbladder and cystic duct in 2 hours
-
Cystic duct obstruction
- Failure to outline Gallbladder within 2 hours
VII. Efficacy: Acute Cholecystitis
- Test Sensitivity: 97%
- Test Specificity: 77%
- Negative Predictive Value: 99%