What is the role of nuclear imaging in the workup of cholangiocarcinoma?

Updated: Apr 13, 2018
  • Author: Mahesh Kumar Neelala Anand, MBBS, DNB, FRCR; Chief Editor: John Karani, MBBS, FRCR  more...
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Answer

Answer

Technetium-99m (99mTc) sulfur colloid and 99mTc acetanilide iminodiacetic acid analogues may be used to demonstrate cholangiocarcinomas.

Approximately 85% of the volume of intravenously injected 99mTc sulfur colloid accumulates in the liver because of hepatocyte uptake. Intrahepatic cholangiocarcinomas are seen as cold liver lesions. The appearances on the scan do not suggest a primary diagnosis of cholangiocarcinoma. Cold lesions due to benign disease, trauma, and abscesses may be present. The technique helps in localizing the lesions when they are larger than 2 cm.

Tc-99m diisopropyl iminodiacetic acid (DISIDA) is excreted into the biliary ducts and may reveal the site of biliary obstruction. After injection, the CBD and cystic duct are usually visualized within 15 minutes. The ducts might not be visualized, even in healthy patients.

Positron emission tomography (PET) is a noninvasive imaging technique that can be used to assess metabolism with the administration of positron-emitting radiolabeled tracers. Fluorodeoxyglucose is one such tracer that has been used in evaluating malignancies. Keiding et al used PET to improve the detection of intrahepatic cholangiocarcinoma in patients with superimposed PSC; their data are promising. The study group comprised 20 patients. [20] Larger prospective studies are required to further assess this technique.

In an Italian study, fluorine-18-fluorodeoxyclucose (18F-FDG) and PET or PET/CT were demonstrated to be accurate diagnostic imaging methods for primary tumor evaluation in patients with cholangiocarcinoma. These tools were found to have a better diagnostic accuracy in patients with intrahepatic cholangiocarcinoma than in patients with extrahepatic cholangiocarcinoma. [21]

Focal defects on sulfur colloid scans are nonspecific. The point of obstruction demonstrated on the DISIDA scan may be due to tumor or benign causes.

The appearances on the sulfur colloid and iminodiacetic acid (IDA) scans are nonspecific. The techniques probably are sensitive for larger lesions and may demonstrate the level of obstruction. False-positive findings on sulfur colloid scans may occur because of benign tumors and other malignant tumors. False-negative findings occur when the tumors are smaller than 2 cm and central in location. False-positive findings on IDA scans may occur because of benign biliary tumors and ductal stones complicated by infection.


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