Making the diagnosis of a hepatobiliary cancer

"Xrays" or radiologic imaging is an important part of the staging of hepatobiliary cancers. Ultrasound, Computerized Tomography (CT), and Magnetic Resonance Imaging (MRI) are three types of imaging that are used to determine what type of liver cancer is present, its location. Radiologists carefully evaluate all this information to help make an accurate diagnosis.

Ultrasound

Ultrasound is commonly used as the first imaging study for liver, gall bladder and bile duct diseases. If a person is at increased risk of developing liver cancer (due to chronic viral hepatitis or liver cirrhosis) their doctor may be recommend that they have regular ultrasound exams to screen for liver cancers in their early (and treatable) stage. Ultrasound is painless, safe and less expensive than CT or MRI. Ultrasound can show solid organs such as the liver, kidneys, spleen, and pancreas. If needed, a Doppler exam can be performed to show blood flow through the liver.

If there is any tumor in the liver, it will be seen as a bright or dark area within the liver on ultrasound scan (Fig 1). The appearance of the liver mass on an ultrasound exam may suggest a specific diagnosis, but a CT scan or MRI is usually required to know the exact diagnosis with certainty.

An abdominal ultrasound exam is frequently used to see if there is an abnormality within the gallbladder, such as a gallstone, or bile duct obstruction. If there is any blockage, enlarged (dilated) bile ducts will be easily seen as dark dilated tubes on the ultrasound scan (Figures 1 & 2).

Fig 1. Ultrasound scan shows a mass (arrow) in the liver which is darker than surrounding normal liver. The mass was later diagnosed as primary liver cancer.

Fig 2. Ultrasound scan shows dilated bile duct due to obstructing cancer (arrow).

CT Scan

CT scan (or CAT scan) uses x-rays to produce cross-sectional (pictures through the body in a horizontal direction) images. CT is considered the standard imaging technique for the diagnosis and staging of most liver and bile duct cancers. Oral and intravenous ("iv") contrast are routinely given before the CT, but the radiologist will decide if contrast is needed or not. These contrast materials are helpful in showing abdominal organs, blood vessels, and tumors or other disease. There is a minimal risk of allergic reactions (and kidney problems) from contrast material.

A tumor in the liver is seen as a brighter or darker area than a normal liver on a CT scan. (Figure 3) CT scan provides a thorough "map" of the tumor itself and if it has spread to other organs. Recent advances in CT technology and 3-dimensional imaging technologies have greatly improved the diagnostic capability of CT scan in liver and bile duct tumor imaging.

Fig 3. CT scan shows a mass (arrow) in the liver which is brighter than normal liver. The mass was diagnosed as primary liver cancer.

MRI

MRI is usually performed when the appearance of the liver lesion on CT and/or ultrasound scan is not conclusive. MRI exam is more complicated and takes a longer time than CT or ultrasound scan. MRI uses a strong magnetic field and does not involve exposure to radiation. The risk of allergic reaction to MRI contrast is much lower than to CT contrast material.

MRI shows more information than CT or ultrasound scan. MRI also uses a few different types of contrast material which can be useful in particular cancers. MRI is also an excellent technique to image the bile ducts.

Fig 4. A bile duct visualization technique of MRI shows dilated bile duct and an obstruction (arrow) due to a bile duct cancer.

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Bile duct cancer and cholangiocarcinoma

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Making the diagnosis of a hepatobiliary cancer

Ultrasound

CT Scan

MRI