Computed Tomography (CT or CAT) Scan of the Liver and Biliary Tract
(CT Scan of the Liver, Biliary Tract, Pancreas, Spleen, and Gallbladder)
What is a CT or CAT scan of the liver and biliary tract?
Computed tomography (CT or CAT scan) is a noninvasive diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce horizontal, or axial, images (often called slices) of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than standard X-rays.
In standard X-rays, a beam of energy is aimed at the body part being studied. A plate behind the body part captures the variations of the energy beam after it passes through skin, bone, muscle, and other tissue. While much information can be obtained from a standard X-ray, a lot of detail about internal organs and other structures is not available.
In computed tomography, the X-ray beam moves in a circle around the body. This allows many different views of the same organ or structure. The X-ray information is sent to a computer that interprets the X-ray data and displays it in a two-dimensional (2D) form on a monitor.
CT scans may be done with or without "contrast." Contrast refers to a substance taken by mouth and/or injected into an intravenous (IV) line that causes the particular organ or tissue under study to be seen more clearly. Contrast examinations may require you to fast for a certain period of time before the procedure. Your doctor will notify you of this prior to the procedure.
CT scans of the liver and biliary tract (the liver, gallbladder, and bile ducts) can provide more detailed information about the liver, gallbladder, and related structures than standard X-rays of the abdomen, thus providing more information related to injuries and/or diseases of the liver and biliary tract.
CT scans of the liver and biliary tract may also be used to visualize placement of needles during biopsies of the liver or during aspiration (withdrawal) of fluid from the area of the liver and/or biliary tract. CT scans of the liver are useful in the diagnosis of specific types of jaundice (yellowing of the skin and eyes as a result of certain conditions of the liver).
Other related procedures that may be used to diagnose liver and biliary tract problems include abdominal X-rays, liver scan, gallbladder scan, abdominal ultrasound, and abdominal angiogram. Please see these procedures for additional information.
The liver and biliary system
The liver is the largest organ in the body. The liver is located in the upper right-hand portion of the abdominal cavity, beneath the diaphragm, and on top of the right kidney and intestines. Shaped like a cone, the liver is a dark reddish-brown organ.
The liver holds about one pint (13 percent) of the body's blood supply at any given moment. The liver consists of two main lobes, both of which are made up of thousands of lobules. These lobules are connected to small ducts that connect with larger ducts to ultimately form the hepatic duct. The hepatic duct transports the bile produced by the liver cells to the gallbladder and duodenum (the first part of the small intestine).
The liver carries out many important functions, such as:
Making bile. Fluid that helps break down fats and gets rid of wastes in the body
Changing food into energy
Clearing the blood of drugs and other poisonous substances
Producing certain proteins for blood plasma
Regulating blood clotting
The biliary system consists of the organs and ducts (bile ducts, gallbladder, and associated structures) that are involved in the production and transportation of bile.
Reasons for the procedure
A CT scan of the liver and biliary tract may be performed to assess the liver and/or gallbladder and their related structures for tumors and other lesions, injuries, bleeding, infections, abscesses, unexplained abdominal pain, obstructions, or other conditions, particularly when another type of examination, such as X-rays, physical examination, and ultra sound is not conclusive.
A CT scan of the liver may be used to distinguish between obstructive and nonobstructive jaundice. Another use of CT scans of the liver and biliary tract is to provide guidance for biopsies and/or aspiration of tissue from the liver or gallbladder.
There may be other reasons for your doctor to recommend a CT scan of the liver and biliary tract.
Risks of the procedure
You may want to ask your doctor about the amount of radiation used during the CT procedure and the risks related to your particular situation. It is a good idea to keep a record of your past history of radiation exposure, such as previous CT scans and other types of X-rays, so that you can inform your doctor. Risks associated with radiation exposure may be related to the cumulative number of X-ray examinations and/or treatments over a long period of time.
If you are pregnant or suspect that you may be pregnant, you should notify your doctor. Radiation exposure during pregnancy may lead to birth defects.
If contrast dye is used, there is a risk for allergic reaction to the dye. Patients who are allergic to or sensitive to medications should notify their doctor. Studies show that 85 percent of the population will not experience an adverse reaction from iodinated contrast; however, you will need to let your doctor know if you have ever had a reaction to any contrast dye, and/or any kidney problems. A reported seafood allergy is not considered to be a contraindication for iodinated contrast. If you are taking metformin/Glucophage or a related medication, you will be asked to stop taking it for at least 48 hours after receiving the contrast, as it may cause a condition known as metabolic acidosis, or an unsafe change in your blood pH.
Patients with kidney failure or other kidney problems should notify their doctor. In some cases, the contrast dye can cause kidney failure, especially if the person is dehydrated or has underlying kidney problems. The effects of kidney disease and contrast agents have attracted increased attention over the last decade, as patients with kidney disease are more prone to kidney damage after contrast exposure.
There may be other risks depending on your specific medical condition. Be sure to discuss any concerns with your doctor prior to the procedure.
Certain factors or conditions may interfere with the accuracy of a CT scan of the liver and biliary tract. These factors include, but are not limited to, the following:
Metallic objects within the abdomen, such as surgical clips
Presence of barium in the intestines from a recent barium study
Previous procedure using oral or IV contrast within a certain period of time, as the contrast may be broken down by the liver and excreted in the bile
Before the procedure
Your doctor will explain the procedure to you and offer you the opportunity to ask any questions that you might have about the procedure.
If your procedure involves the use of contrast dye, you will be asked to sign a consent form that gives permission to do the procedure. Read the form carefully and ask questions if something is not clear.
Notify the radiologic technologist if you have ever had a reaction to any contrast dye, or if you are allergic to iodine.
Generally, there is no fasting requirement prior to a CT scan, unless a contrast dye is to be used. Your doctor will give you special instructions ahead of time if contrast is to be used and if you will need to withhold food and drink.
Notify your doctor of all medications (prescribed and over-the-counter) and herbal supplements that you are taking.
Notify the radiologic technologist if you are pregnant or suspect you may be pregnant.
Notify the technologist if you have any body piercing on your chest and/or abdomen.
Based on your medical condition, your doctor may request other specific preparation.
During the procedure
CT scans may be performed on an outpatient basis or as part of your stay in a hospital. Procedures may vary depending on your condition and your doctor's practices.
Generally, a CT scan of the liver and biliary tract follows this process:
You will be asked to remove any clothing, jewelry, or other objects that may interfere with the procedure.
If you are asked to remove clothing, you will be given a gown to wear.
If you are to have a procedure done with contrast, an intravenous (IV) line will be started in the hand or arm for injection of the contrast dye. For oral contrast, you will be given a liquid contrast preparation to swallow.
You will lie on a scan table that slides into a large, circular opening of the scanning machine. Pillows and straps may be used to prevent movement during the procedure.
The technologist will be in another room where the scanner controls are located. However, you will be in constant sight of the technologist through a window. Speakers inside the scanner will enable the technologist to communicate with and hear you. You will have a call button so that you can let the technologist know if you have any problems during the procedure. The technologist will be watching you at all times and will be in constant communication.
As the scanner begins to rotate around you, X-rays will pass through the body for short amounts of time. You will hear clicking sounds, which are normal.
The X-rays absorbed by the body's tissues will be detected by the scanner and transmitted to the computer. The computer will transform the information into an image to be interpreted by the radiologist.
It will be important that you remain very still during the procedure. You may be asked to hold your breath at various times during the procedure.
If contrast dye is used for your procedure, you will be removed from the scanner after the first set of scans has been completed. A second set of scans will be taken after the contrast dye has been administered.
If contrast dye is used for your procedure, you may feel some effects when the dye is injected into the IV line. These effects include a flushing sensation, a salty or metallic taste in the mouth, a brief headache, or nausea and/or vomiting. These effects usually last for a few moments.
You should notify the technologist if you feel any breathing difficulties, sweating, numbness, or heart palpitations.
When the procedure has been completed, you will be removed from the scanner.
If an IV line was inserted for contrast administration, the line will be removed.
You may be asked to wait for a short period of time while the radiologist examines the scans to make sure they are clear.
While the CT procedure itself causes no pain, having to lie still for the length of the procedure might cause some discomfort or pain, particularly in the case of a recent injury or invasive procedure such as surgery. The technologist will use all possible comfort measures and complete the procedure as quickly as possible to minimize any discomfort or pain.
After the procedure
If contrast dye was used during your procedure, you may be monitored for a period of time for any side effects or reactions to the contrast dye, such as itching, swelling, rash, or difficulty breathing.
If you notice any pain, redness, and/or swelling at the IV site after you return home following your procedure, you should notify your doctor as this could indicate an infection or other type of reaction.
Otherwise, there is no special type of care required after a CT scan of the liver and biliary tract. You may resume your usual diet and activities unless your doctor advises you differently. Your doctor may give you additional instructions after the procedure, depending on your particular situation.