Imaging tests are studies that make pictures of what's going on inside your body. These tests use different forms of energy (x-rays, sound waves, radioactive particles, or magnetic fields) that are passed through the body. The changes in energy patterns caused by different body tissues can be detected by special devices, which change them into pictures. These pictures can show normal body structure and function as well as abnormalities caused by diseases such as cancer.

Imaging tests are different from endoscopic tests (for example, colonoscopy or bronchoscopy), which use a flexible, lighted tube connected to a viewing lens or a video camera. Endoscopic tests allow doctors to look inside parts of the body as if they were looking with the "naked eye." (For more information, see the American Cancer Society document, Endoscopy.)

What Are Imaging Tests Used For?

Imaging tests are used for cancer in many ways:

• They are sometimes used in screening – looking for cancer in its early stages, even though a person has no symptoms. A mammogram is an example of an imaging test used for cancer screening.

• They sometimes help predict whether a tumor is likely to be cancer and help doctors decide if you need to have a biopsy (taking a tissue sample to be looked at under the microscope) . A biopsy is almost always needed to know for sure that a tumor is cancer.

• They sometimes help predict whether a tumor is likely to be cancer and help doctors decide if a biopsy (removal of a tissue sample for viewing under the microscope) is needed. However, a biopsy is almost always needed to say for sure that a tumor is cancer.

• They show exactly where the tumor is, even deep within the body, so that a sample of it can be taken for further study.

• They help stage cancer (determining how far the cancer has spread).

• They can be used to plan treatment, such as when determining where the beams should be focused in radiation therapy.

• They can give a doctor an idea of how well treatment is working (that is, if a tumor has shrunken, stayed the same, or grown after treatment).

• They can help find out if a cancer has recurred (come back) after treatment.

Imaging tests are only part of the process of cancer diagnosis and management. A complete initial workup for your cancer also includes a careful medical history (interview about symptoms and risk factors) and physical exam, and possibly blood or other lab tests.

Imaging tests may give important evidence that a lump or mass is present, but they usually cannot tell for sure if the lump is a cancer. For the doctor to make a diagnosis, a biopsy is almost always needed. In many cases, imaging tests make it possible to get a biopsy without the need for major surgery.

Many doctors request x-rays or other images before treatment begins so that a record is available showing how things change over time. These studies are called baseline studies because they provide a basis of information that helps doctors evaluate the results of treatment or progression of the disease.

Who Performs and Interprets Imaging Tests?

A doctor, a certified technologist, or other health professional may perform an imaging test. Depending on the technology involved, the test may be done in a hospital, a special clinic or imaging center, or a doctor's office. In larger medical centers, imaging tests are usually done in the radiology department (even though some types of tests do not involve high-energy radiation).

A radiologist, a doctor who specializes in imaging techniques, usually reads (interprets) the imaging test. The radiologist writes a report on the findings and sends the report to your doctor. A copy of the report will become part of your patient records. Your other doctors (oncologists, surgeons, etc.) may look at the images as well.

Types of Imaging Tests

The rest of this document explains some of the more common types of imaging tests, how they are done, and when they may be needed.

Computed Tomography (CT) Scan

Other Names

CT scan, CAT scan, spiral CT, helical CT

What Does It Show?

Computed tomography or CT (also called CAT) scans show a slice, or cross-section, of the body. The image shows your organs and soft tissues more clearly than standard x-rays. Because the image is created by a computer, it can be enlarged to make it easier to read and interpret.

Since the late 1970s, CT scans have been a very valuable technology in detecting cancer. CT scans can show a tumor's shape, size, volume, and location and can reveal the blood vessels that feed the tumor.

Doctors often use CT scans to help them guide a needle to remove a tissue sample (called a CT-guided biopsy). They can also be used to guide needles into tumors for some types of cancer treatments, such as radiofrequency ablation (destroying a tumor using heat and ionic agitation).

CT scans are especially effective in detecting and evaluating cancer in the liver, pancreas, adrenal glands, lungs, and bones. They are also used to provide information about cancer in the large and small intestines, esophagus, stomach, brain, prostate, or other organs.

By comparing CT scans done over time, doctors can see how a tumor is responding to therapy or detect a possible recurrence after treatment.

How Does It Work?

CT scans use controlled amounts of x-rays – beams of high-energy radiation that are passed through the body – to create images. In a way, CT scans are like ordinary x-ray tests (see Radiographic Studies below). But an x-ray test uses a broad beam of radiation aimed from only one angle. A CT scan uses a pencil-thin beam to create a series of pictures taken from different angles. Each angle produces a slightly different view of your internal organs and soft tissues. The information from each angle is fed into a computer, which calculates how the images overlap. The computer then creates a single black and white image that shows a “slice” of a specific area of your body (much like looking at a single slice from a loaf of bread).

The image can be made clearer by the use of a special contrast “dye,” which can be swallowed as a liquid, injected into a vein, or infused as an enema. Because body tissues absorb this material differently, the resulting CT image will have greater contrast between types of tissues, allowing abnormalities such as tumors to be seen more clearly.

In recent years, spiral CT (also known as helical CT) has become available. This type of CT scan uses a faster machine. The scanner part of the machine rotates around the body continuously, allowing doctors to collect the images much more quickly than standard CT. As a result, you do not have to hold your breath for as long while the image is taken. This lowers the chance of blurred images occurring as a result of breathing motion. It also lowers the dose of radiation received during the test. The “slices” it images are thinner, which yields more detailed pictures. Spiral CT is currently used to look at liver, pancreas, lung, and some other tumors.

By placing spiral CT image slices on top of each other, doctors can create a 3-dimensional (3D) scan, which provides even more information about certain cancers. The 3-dimensional image can be rotated on a computer screen to allow for different views.

Doctors are now taking this technology one step further in a technique called virtual endoscopy. They can view the inside surfaces of organs such as the lungs (virtual bronchoscopy) or colon (virtual colonoscopy, also called CT colonography) without actually having to insert anything into the body. They can manipulate the 3D images to create a black and white “fly-through” view on the computer screen, which looks as it would if they were performing an actual endoscopy. Studies are now under way to determine if these techniques are as good as conventional endoscopy.

How Do I Prepare for the Test?

CT scans are normally done on an outpatient basis, meaning that you do not need to be admitted to the hospital.

In some cases, your doctor may tell you not to eat or drink for several hours before the exam or may require you to have an enema to cleanse the bowel and remove material that could interfere with viewing the abdominal area. Depending on the part of the body being studied, you also may need to drink contrast liquid or receive a contrast enema before the test. If a contrast material is to be injected into a vein, you may have an intravenous (IV) catheter inserted into an arm vein.

You may be asked to undress, put on a robe, and remove any jewelry or other metal objects that may interfere with the image. If you are having a head CT scan, you should remove dentures, hearing aids, hair clips, and so on.

What Is It Like Having the Test?

A radiologic technologist conducts the CT scan. You lie on a thin, flat table connected to a scanner. The scanner is a large, doughnut-shaped machine. The table can slide back and forth inside the hole in the middle of the scanner. As the table moves into the opening, an x-ray tube rotates within the scanner, emitting thousands of tiny x-ray beams at specific angles. These beams pass through the body and are detected on the other side of the scanner. Each full rotation of the x-ray tube results in an image of a slice of the body. You may hear buzzing and clicking as the scanner switches on and off.

During a head CT scan, your head will be held still with a special device.

The test is painless but you may find it uncomfortable to hold still in certain positions for minutes at a time. You may also be asked to hold your breath, since chest movement can affect the quality of the image. If a spiral CT machine is used, the time you hold your breath is shortened.

If you are given contrast material in a vein, you will probably have a scan first, then receive the injection, then undergo a second scan.

How Long Does It Take?

Depending on how much of your body your doctors want to examine and whether contrast material is used, a CT scan can take anywhere from 10 to 30 minutes. Spiral CT scans take less time. More time is taken getting you into position and in giving contrast material than in actually taking the pictures. After the test, you may be asked to wait while the images are looked at to see if more images are needed.

What Are the Possible Complications?

About 5% of people have some type of reaction to the contrast dye. Possible symptoms include:

• nausea
• wheezing
• shortness of breath
• a metallic or bitter taste in the mouth
• a feeling of flushing or warmth that lasts for a few minutes
• itching or facial swelling that can last up to an hour

These symptoms usually are not serious, and most often they disappear on their own, but be sure to let your health care team know if you begin to have any of them.

In rare cases, people have a severe allergic reaction that causes trouble breathing and requires treatment with medicines, such as epinephrine. If there is a risk that you might have an allergic response, you may be given a test dose of the contrast material first.

Be sure to let your health care team know if you’ve had a reaction to contrast dye (or to seafood or iodine) in the past.

What Else Should I Know About This Test?

• Although a CT scan is sometimes described as a "slice" or a "cross-section," no cutting or incisions are involved.

• The amount of radiation received during a CT scan is more than that with a standard x-ray.

• People who are very overweight may have trouble fitting into the CT scanner.

• Tell your doctor if you have an allergy or are sensitive to iodine, seafood, or contrast dyes.

• CT scans can cost up to 10 times as much as a standard x-ray.

Magnetic Resonance Imaging (MRI)

Other Names

magnetic resonance (MR), nuclear magnetic resonance (NMR) imaging

What Does It Show?

Like computed tomography (CT) scans, MRI displays a cross-section of your body. However, MRI uses powerful magnetic fields instead of radiation to create the images. An MRI scan can present cross-sectional slices (views) from several angles, as if someone were looking at a slice of your body from the front (frontal view), from the side (sagittal view), or from above your head (axial view). The procedure creates images of soft tissue parts of the body that would sometimes be hard to see using other imaging tests.

MRI is especially valuable in detecting and localizing cancer in the brain and spinal cord, head, neck, and bones and muscles. Used with contrast agents, it is the best way to see brain tumors. Using MRI, doctors can sometimes tell a benign tumor from a malignant (cancerous) tumor.

In recent years, MRI has become the main way to thoroughly evaluate the female reproductive system, and it is helpful in determining the stage of endometrial cancer before surgery. Another important use for MRI is looking for signs that cancer may have metastasized (spread) to the liver from another site in the body.

MRI images can also help doctors plan treatment such as surgery or radiation therapy.

Unlike x-rays or CT scans, MRI cannot detect calcifications (tiny mineral deposits that may suggest the presence of cancer) in tissues such as the breast. However, special MRI machines, now available in a few hospitals, are designed specifically for examining the breast. MRI is sometimes used along with mammograms or breast ultrasound to look for breast cancer, particularly in younger women or those with very dense breasts. At this time MRI is not recommended by itself for the early detection of breast cancer.

How Does It Work?

An MRI scanner is a cylinder that houses a very strong magnet weighing several tons. As you lie on a table within the scanner, the device surrounds you with a powerful magnetic field. The magnetic force causes the nucleus (center) of hydrogen atoms in your body to line up in one direction. Once the atoms are "standing at attention," the MRI machine emits a burst of radio-frequency waves. These waves cause the hydrogen atom nuclei to change their alignment. When the nuclei return to their original position, they emit certain signals, which the scanner detects. Hydrogen nuclei in different tissues change alignment in different ways. A computer interprets the signals resulting from these changes and converts them into a 2- or 3-dimensional black and white image.

Contrast materials can be injected through a vein to improve the quality of the image. Once absorbed by the body, these agents speed up the rate at which tissue responds to stimulation from magnetic and radio waves. As a result, the signals produce stronger and clearer images.

How Do I Prepare for the Test?

No special diet or preparation is needed before an MRI.

Some tests require injection of a contrast medium prior to the imaging. If a contrast material is to be injected, you may have an intravenous (IV) catheter inserted into an arm vein.

If being placed in an enclosed space such as the MRI scanner concerns you, you may need to take medicine to help you relax. Talking with the technologist or a patient counselor or getting a "tour" of the MRI machine before the test can be helpful. Ideally, you will be able to see and hear what's going on through the use of an intercom system. You will also have a call button should you need to speak with someone. In some cases, you can arrange to have the test done with an open MRI machine that allows more space around your body (see below).

Before the test, you may need to undress and put on a gown. Be sure to remove any metal objects. Before the scan, the MR technologist will ask you if you have any metal in your body, such as surgical clips or staples, pacemakers, artificial joints, metal fragments, tattoos, permanent eyeliners, and so on. Some metallic objects will not cause problems, but others might. You may need to have an x-ray to check for metal objects if there is any doubt.

What Is It Like Having the Test?

MRI scans are usually done on an outpatient basis in a hospital or clinic. You will lie down on a flat table. The technologist sometimes attaches straps to help keep you from moving or pillows to hold you in position. The table then glides through an opening in the cylinder. The part of your body that is being examined will be positioned in the center of the device.

The test is painless, but you have to lie still inside the cylinder, the surface of which is a few inches from your face. You may be asked to hold your breath during certain parts of the test. The machine may make loud, thumping noises, similar to the sound of hammering, as the magnet switches on and off. Some facilities allow you to wear earplugs or headphones during testing.

Newer machines that are less restrictive may be easier to tolerate. These open MRI machines replace the cylinder with a larger ring. This design lessens the banging sound and the claustrophobic feeling of lying in an enclosed space. However, the device does not generate as powerful a magnetic field. While open MRI technology is improving, the images may not be as clear or detailed as they are with standard MRI. In some cases, this may require retesting on a standard MRI machine.

How Long Does It Take?

MRI scans can take a long time – typically between 45 and 60 minutes and sometimes up to 2 hours. After the test, you may be asked to wait while the images are looked at to see if more images are needed.

What Are the Possible Complications?

Some people have mild reactions to the contrast agents. Such reactions include:

• nausea
• pain at the injection site
• headache that develops a few hours after the test is over

These symptoms are much less common with MRI contrast agents than with those used for CT scans, but be sure to let your health care team know if you experience any of them.

Some people become very uncomfortable, even panicky, when lying inside the MRI scanner.

What Else Should I Know About This Test?

• People who are overweight may have trouble fitting into the MRI machine.

• Some kinds of metallic surgical implants, such as pacemakers, certain types of surgical clips or staples, or implanted pumps, may cause problems due to the strong magnetic field. Your health care team will ask you questions about these before the procedure.

• If you have an implanted intravenous (IV) catheter or port for long-term delivery of medication, your doctor will need to determine whether you should have an MRI.

• If you have tattoos or permanent makeup (such as eyeliner), let the technician know so that they can take the needed precautions and ensure the best results.

• MRI does not involve exposure to radiation.

• The use of MRI during pregnancy has not been well studied. MRI is usually avoided in the first 12 weeks of pregnancy unless there is a strong medical reason to use it.

• Do not bring credit cards with you into the exam room – the magnet could wipe out the information stored on the card.

• MRI is more expensive than a CT scan and may not be available in some areas.

Radiographic Studies (Regular X-rays and Contrast Studies)

Other Names

radiographs, roentgenograms; for names of contrast studies, see Table 1 below.

What Do They Show?

Radiographs, commonly known as x-rays, produce shadow-like images of certain organs or tissues. An abdominal x-ray may reveal tumors or other diseases in organs of the abdomen, including the intestines, stomach, liver, spleen, and kidneys. A chest x-ray is used to detect lung diseases, including cancer. These tests, which produce a single image or series of still images, are sometimes referred to as standard radiographic studies. Mammography (a breast x-ray) is another form of radiographic study (for more information, see the section Mammography).

Special types of x-ray tests may use dyes called contrast materials. For example, a lower gastrointestinal (GI) series, often called a barium enema exam, takes x-ray images after the bowel is filled with barium sulfate (a contrast material). Another contrast study, intravenous pyelography (IVP), examines the structure and function of the kidneys.

With advances in technology, many contrast studies once commonly used for diagnosis are being replaced by other methods, such as CT or MRI scans (see separate sections).

How Do They Work?

A special tube inside the x-ray machine produces a controlled beam of radiation. Tissues in the body block (absorb) the radiation to varying degrees. Dense tissues such as bones block most radiation, but soft tissues, such as fat or muscle, block less. After passing through the body, the beam falls on a piece of film, where it casts a kind of shadow. Tissues that block high amounts of radiation, such as bone, show up as white areas. Soft tissues block less radiation and show up in shades of gray, and organs that are mostly air (such as the lungs) normally appear black. Tumors are usually denser than the tissue around them, so they are often noticeable as lighter shades of gray.

Contrast studies provide some information that standard x-ray techniques cannot. During a contrast study, you receive a dose of a contrast material that outlines, highlights, or fills in parts of the body so that they show up more clearly on an x-ray image. The contrast material may be given by mouth, as an enema, as an injection, or through a catheter (thin tube) inserted into various tissues of the body. For most of these tests, the images can be captured either on x-ray film or digitally (on a computer).

A summary of the most commonly used contrast studies appears in Table 1.

Table 1: Commonly Used Contrast Studies

Test Name(s)	Organs Studied	Contrast Given by
angiography, angiogram, arteriography, arteriogram	arteries throughout the body, especially brain	catheter in an artery
intravenous pyelography (IVP)	urinary tract (kidney, ureters, bladder)	injection into vein
lower GI (gastrointestinal) series, barium enema (BE), double-contrast barium enema (DCBE), air-contrast barium enema (ACBE)	colon, rectum	enema
lymphangiography lymphography	lymph nodes, small lymph vessels	injection through lymph vessel
upper GI series barium swallow esophagography	eophagus, stomach, part of small intestine	mouth

How Do I Prepare for the Test(s)?

Other than removing metal objects that might interfere with the image, no special preparation is needed before having a standard x-ray.

Preparation for a contrast study depends on the specific test. You may be asked not to eat anything or to prepare in other ways before the test (see next section). The radiology center where you are having the test should supply you with instructions. Check with them first. Your doctor also may give you instructions.

What Is It Like Having the Test(s)?

Standard x-rays: Usually x-rays are taken by an x-ray technologist, not by a doctor. You undress to expose the part of the body that will be x-rayed, removing rings or other objects that may interfere with the image. You will be asked to sit, stand, or lie down, depending on what part of the body will be imaged. Your body is placed in contact with a flat box that contains the x-ray film. The technologist then moves the machine to aim the beam of radiation at the correct area. You may have protective shields placed over parts of your body near the area to be x-rayed so that they are not exposed as well. Usually the technologist leaves the room to operate the machine by remote control. Your exposure to the ray is kept to an absolute minimum – usually less than a second. You may hear a short buzzing sound while the machine is working.

For a chest x-ray, views are taken from the front and the side. Your arms will be at your side during the front exposure and will be placed either above your head or in front of you during the side exposure. The technologist will tell you when to take a deep breath and hold still. During an abdominal x-ray, you lie down on a table. You may be asked to change position if several views are needed. Again, you will need to hold your breath and lie still during the exposure. After the exposure, the technologist will return to the room to move the machine out of the way, remove any protective shields, collect the film, and help you back to the changing room where you can get dressed.

Angiography: In the past, angiography was often used to stage (tell the extent of) cancers, but CT and MRI scans are now used more often for these purposes. Angiography is occasionally used to show surgeons the location of blood vessels next to a cancer so that the operation can be planned to limit blood loss. Angiography is still used a great deal to diagnose non-cancerous blood vessel diseases. These types of studies are done by a radiologist, a doctor who specializes in imaging, with the help of technologists.

Your diet will be restricted before this exam. Usually you will receive a sedative to relax you before the test starts. As you lie still on the table, the skin over the injection site is cleansed and numbed. A catheter (thin plastic tube) is inserted into a blood vessel (usually the femoral artery at the top of the thigh) and moved forward until it reaches the area to be studied. The contrast dye is then injected rapidly, and a series of x-ray images is taken. When the pictures are finished, the plastic tube is removed. Firm pressure may be needed on the insertion site for a time to ensure there is no excessive bleeding from the site. You will also be asked to lie flat for up to several hours.

In recent years, advances in technology have led to the development of less invasive forms of angiography. CT angiography captures images of blood vessels using a CT scanner instead of a standard x-ray machine. The contrast dye can be injected into a vein in the arm instead of having to insert a catheter into a major blood vessel, which means the test takes less time and involves fewer risks than standard angiography. Magnetic resonance angiography (MRA) is an MRI study of the blood vessels. It may be done with or without having a contrast dye injected into an arm vein, and is therefore also quicker and less invasive than standard angiography.

Intravenous pyelography (IVP): This test is used to study kidney function and to look for tumors of the urinary tract.

You will likely be asked to not eat or drink anything for about 12 hours before the test, and you will be given laxatives to cleanse the bowel. For the test itself, you lie on a table for a series of x-rays. Contrast material is then given through a vein in your arm. Your kidneys remove the contrast material from the bloodstream, and it enters the urinary tract. Another series of x-rays is taken at intervals over the next 30 minutes or so. Pressure may be applied to the abdomen to improve the clarity of the image. Once the dye has reached the bladder, you will be asked to urinate while another x-ray is taken.

Lower GI series (barium enema): This study is used to look at the lining of the colon (large intestine) and rectum.

Your intake of food and liquid may be restricted a few days before the test. Laxatives and/or enemas are used to cleanse the colon (large intestine). For the test, you lie secured on a table, and a series of x-rays is taken. Then liquid barium is inserted through a small tube placed in your rectum. The liquid feels cool. More images are taken while the table tilts you into different positions. You have to lie still and hold your breath as each image is taken. After the test, you can go to the toilet to excrete the barium solution.

To get clearer pictures, a "double-contrast" exam is often done. This exam uses a smaller quantity of thicker barium liquid, followed by an infusion of air into your bowel. This can cause a sense of fullness, along with an urge to empty your bowels.

Upper GI series (barium swallow): This test is used to study the lining of the esophagus, stomach, and the duodenum (first part of the small intestine).

You will likely be asked to not eat or drink for 8 to 12 hours before the exam. As with the lower GI series, you lie on a tilting table while a series of x-ray images is taken. You will need to swallow a barium mixture, which has a consistency similar to a milkshake, several times during the test. You may also be asked to swallow baking soda crystals to create gas in your stomach. Sometimes pictures are taken several hours later to assess the small intestine. After the test you may take a laxative to speed up removal of the barium from your body.

Lymphangiography: Although not commonly used to detect cancer, a lymphangiogram may be helpful in planning treatment or monitoring a response to treatment for some types of cancer, such as lymphoma.

In some cases, you may be asked to fast or have only a liquid diet before the test. For the test, a blue dye is injected into the skin between your toes to reveal the lymphatic vessels. After a numbing medicine is applied, an incision is made in the foot and a very thin catheter (tube) is inserted into a lymphatic vessel. The contrast material is slowly injected and allowed to travel through the lymph system. This may take an hour or two. Then a series of x-rays are taken. You may be asked to return on the next day or two for more x-rays, but you will not need to have dye injected during these visits.

How Long Do They Take?

• standard x-ray: About 5 to 10 minutes
• angiography: From 1 to 3 hours
• intravenous pyelogram: About 1 hour
• lower GI series: 30 to 45 minutes
• upper GI series: 30 minutes to 6 hours, depending on the part of the digestive system being tested
• lymphangiography: 2 to 5 hours, plus another 30 minutes each time during the next few days for repeat studies

What Are the Possible Complications/Side Effects?

• Standard x-rays: Complications are very unlikely.

• Angiography: You may have a warm or burning feeling as the dye is given. The contrast material may cause nausea, vomiting, flushing, itching, or a bitter or salty taste. In rare cases, people have a severe allergic reaction to the iodine in the contrast material.

  There is a small risk of a blood clot forming on the end of the catheter, which could block a blood vessel. There is also a small risk of damage to the blood vessel from the tip of the catheter, which could lead to internal bleeding. A hematoma (a large collection of blood under the skin) may develop at the incision site if pressure is not kept on it long enough. (Possible complications of CT or MR angiography are less serious and are similar to those described in the sections on CT and MRI).

• Intravenous pyelogram (IVP): The test is generally safe, but it should not be given to people who are sensitive to contrast material with iodine. This causes some people to have nausea, vomiting, flushing, itching, or a bitter or salty taste. In rare cases, people have a severe reaction to the contrast material.

• Lower GI series (barium enema): The test is not painful, but it can be uncomfortable. Some patients have abdominal cramping. Many elderly patients find the procedure tiring. The barium contrast material will make your stools a light color for a few days after the test and may cause constipation.

• Upper GI series (barium swallow): The barium mixture has the thickness of a milkshake and has a chalky taste. Baking soda crystals can cause gas and belching. After the test, your stools will be lighter in color for a few days, and you may be constipated.

• Lymphangiography: The injection can cause discomfort at and near the site of contrast dye injection. An allergic reaction to the dye is possible. The dye can change the color of urine, stool, or skin for the next 1 to 2 days. Changes in the color of the skin around the toes can last for several months.

What Else Should I Know About These Tests?

• X-ray studies expose the body to radiation, but modern x-ray equipment uses the minimum amount of radiation needed (See General Questions and Comments on Radiation Risk for more information.)

• A newer technology, digital radiology, produces images on computer screens rather than on film. The size and contrast of the images can be adjusted to make them easier to read, and they can easily be sent to computers in other medical offices or hospitals through electronic connections.

• If you are to have a test involving the use of a contrast dye, tell your doctor if you have a known allergy to contrast materials or to seafood (which contains high levels of iodine).

Mammography

Other Names

What Does It Show?

A mammogram is an x-ray exam of the breast. It can detect and diagnose many cases of breast cancer.

A mammogram is an effective screening tool. A screening mammogram is used to look for signs of breast disease when you do not have any breast symptoms. Many breast cancers take years to develop. A mammogram can detect cancer in its early stages, when treatment is most likely to be successful.

A diagnostic mammogram is the imaging test used when you have breast symptoms or when abnormalities appear on a screening mammogram. Diagnostic mammograms may include additional views (images) of the breast that are not usually done on screening mammograms.

Mammograms can't prove that an abnormal area is (or is not) cancer, but it can give information that shows whether further testing is needed. The 2 main types of breast abnormalities that can be found with a mammogram are calcifications and masses.

Calcifications are tiny mineral deposits within the breast tissue, which look like small white spots on the films. They may or may not be caused by cancer. There are 2 types of calcifications:

• Macrocalcifications are coarse (larger) calcium deposits that are most likely changes in the breasts caused by aging of the breast arteries, old injuries, or inflammation. These deposits are related to non-cancerous conditions and do not require a biopsy (removing a sample of tissue for viewing under a microscope). Macrocalcifications are found in about half the women over 50, and in 1 of 10 women under 50.

• Microcalcifications are tiny specks of calcium in the breast. They may appear alone or in clusters. Microcalcifications seen on a mammogram are of more concern, but still usually do not mean that cancer is present. The shape and layout of microcalcifications help the radiologist judge how likely it is that cancer is present. In most instances, the presence of microcalcifications does not mean a biopsy is needed. In other cases, the microcalcifications look more suspicious and a biopsy is needed.

A mass, which may occur with or without calcifications, is another important change seen on mammograms. Masses can be caused by many things, including cysts (non-cancerous, fluid-filled sacs) and non-cancerous solid tumors, but they could be cancer and usually should be biopsied if they are not cysts.

• A cyst cannot be diagnosed by physical exam alone, nor can it be diagnosed by a mammogram alone. To confirm that a mass is really a cyst, either breast ultrasound or removal of fluid with a thin, hollow needle (aspiration) is needed.

• If a mass is not a simple cyst (that is, if it is at least partly solid), then you may need to have more imaging tests. Some masses can be watched with periodic mammograms, while others may need a biopsy. The size, shape, and margins (edges) of the mass help the radiologist to determine whether cancer may be present.

Your prior mammograms may help show that a mass has not changed for many years, which would mean that the mass is likely a benign condition and a biopsy would not be needed. Having your prior mammograms available to the radiologist is very important.

A mammogram may show something suspicious, but by itself it cannot prove that an abnormal area is cancer. If a mammogram raises a suspicion of cancer, tissue must be removed and looked at under the microscope to tell if it is cancer. This can be done with a needle biopsy or an open surgical biopsy.

To get an accurate breast biopsy, enough cells or fluid must be removed from the suspicious area for the pathologist to study. It can be hard for a doctor to insert the needle precisely where the abnormality exists, especially if the lump cannot be felt. To improve accuracy, your doctor may use different imaging studies to guide the placement of the needle:

• Stereotactic mammography uses mammograms taken from 2 angles (a "stereo" view). A computer calculates the precise location of the mass or calcification and then guides the placement of the biopsy needle.

• Breast ultrasound can also be used to guide biopsy needles (see the section on Ultrasound).

A ductogram (galactogram) is a type of mammogram that is done after a contrast agent is inserted into a nipple duct with a thin tube. It is used to evaluate nipple discharge.

How Does It Work?

A mammogram uses a machine designed specifically to examine your breast tissue. The machine takes a different form of x-ray and at lower doses than a usual x-ray. Because these x-rays do not go through tissue easily, the machine has 2 plates that compress the breast to spread the tissue apart. This gives a more accurate image using less radiation.

Digital mammography: Digital mammography (also known as full-field digital mammography or FFDM) is similar to standard mammography in that x-rays are used to produce an image of the breast. The differences are in the way the image is recorded, viewed by the doctor, and stored. Standard mammogram images are recorded on large sheets of photographic film, whereas digital images are captured electronically and viewed on a computer screen. They are stored on a computer and their magnification, brightness, or contrast can be changed after the exam is done to help the doctor see certain areas more clearly. Digital images can be sent electronically from one location to another for remote consultation with breast specialists. While many centers do not offer the digital option at this time, it is expected to become more widely available in the future.

Because digital mammograms cost more than standard mammograms, studies are now under way to determine which form of mammogram will benefit more women in the long run. Some studies have found that women who have digital mammograms have to return less often for additional imaging tests because of inconclusive areas on the original mammogram. A recent large study from the National Cancer Institute found that digital mammography was more accurate than film mammography in finding cancers in women younger than 50 and in women with dense breast tissue, although the rates of inconclusive results were similar between digital mammography FDM and film mammography. It is important to remember that standard film mammography is also effective for these groups of women, and that they should not skip their regular mammogram if a digital mammogram is not available.

Over the past 2 decades, computer-aided detection and diagnosis (CAD) has been developed to help radiologists detect suspicious areas on mammograms. This is done most commonly with screen-film mammograms and less often with digital mammograms.

Computers can help doctors identify abnormal areas on a mammogram by acting as a second set of “eyes.” For standard mammograms, the film is fed into a machine which converts the image into a digital signal that is then analyzed by the computer. Alternatively, the technology can be applied to an image captured with digital mammography. The computer then displays the image on a video screen, with markers pointing to areas it "thinks" the radiologist should check especially closely.

Early tests have found that CAD can help find some cancers that doctors might have otherwise missed. But doctors still disagree about how many cancers the device will pick up. Some doctors feel that the device is not as effective as simply having a second radiologist review the films. Others are concerned that the device may lead to unnecessary biopsies by falsely identifying benign abnormalities as being suspicious for cancer. Most breast specialists are encouraged by recent progress in computer-aided detection and look forward to more technical refinements and studies that help to clarify its role in breast cancer detection.

A ductogram uses a contrast dye to outline a breast duct (a tube through which milk passes) on an x-ray. This allows a doctor to see any growths or other abnormalities within it that may be causing nipple discharge.

How Do I Prepare for the Test?

The best time to schedule a mammogram is one week after your period, when your breasts are likely to be less sensitive.

You’ll need to undress from the waist up for the exam, so you may want to wear a shirt or blouse and a skirt or pants, rather than a dress, to make undressing easier. No special preparation, such as diet restriction, is necessary. However, on the day of your mammogram, do not use deodorants, perfumes, powders, or ointments under your arms or on your breasts because these may interfere with the images.

A screening mammogram usually requires 2 views of each breast – one from the top and one from the side. You may need to have more images taken to include as much breast tissue as possible, especially if the mammogram is being used for diagnosis or for guiding the placement of a needle for biopsy or if you have breast implants.

What Is It Like Having the Test?

You will be asked to undress from the waist up and to remove any jewelry around your neck. Your breast will rest on a flat surface. The compression will feel tight, but it should not be very painful. You hold your breath while the technologist takes the picture.

For a ductogram, the nipple is first cleaned and sterilized. The doctor then applies gentle pressure to look for discharge and find the opening of the duct. He or she then inserts a very thin tube into the nipple duct and slowly infuses a contrast dye.

How Long Does It Take?

The screening mammogram from start to finish takes about 15 to 20 minutes. A diagnostic mammogram, involving images from more angles or close-up views, takes a total of 30 to 45 minutes. The breast is compressed for only a few seconds of that time. Ductograms may take a little longer.

What Are the Possible Complications?

A mammogram involves low doses of radiation and is safe. The very low risk that cancer may result from exposure to radiation during a mammogram is far outweighed by the benefits of detecting an early cancer.

Some women find that mammograms are painful, but for most the compression causes only temporary discomfort.

There have been reports of breast implant ruptures during mammography, but these are very rare.

Because ductograms involve the use of a contrast material, some women may have allergic reactions to them. In some cases the doctor may have trouble finding the opening of the duct, which may require probing the area or even rescheduling the exam a week or two later.

What Else Should I Know About This Test?

The American Cancer Society has developed guidelines for the early detection of breast cancer in women who are not having breast symptoms:

• Women 40 years of age and older should have a mammogram every year and a clinical breast exam (CBE) performed by a health care professional every year. They also have the option of performing a breast self-exam (BSE) every month. The CBE should be conducted close to and preferably before the scheduled mammogram.

• Women aged 20 to 39 should have a clinical breast exam by a health care professional every 3 years and have the option of performing breast self-exam every month.
• Women at high risk (greater than 20% lifetime risk) should get an MRI and a mammogram every year. Women at moderately increased risk (15% to 20% lifetime risk) should talk with their doctors about the benefits and limitations of adding MRI screening to their yearly mammogram. See Breast Cancer: Early Detection for more information on breast cancer risk.

Mammography alone cannot detect all cases of breast cancer. For this reason, mammograms should be used in addition to a clinical breast exam by a health care professional. Knowing how your breasts normally look and feel, and reporting any changes to your doctor, is also very important.

To reduce the chance of discomfort during a mammogram, schedule the procedure for a week or so after your menstrual period, when your breasts are less likely to be tender.

A negative mammogram (no sign of calcifications or masses) does not necessarily mean that cancer is not present or that cancer will not develop later.

The need for a biopsy does not mean that you have cancer. About 70% to 80% of biopsies turn out to be benign (not cancer).

If you have breast implants, find a radiologist who is experienced in performing mammograms on augmented breasts and let the facility know this ahead of time. Additional views may be necessary, so it may take longer.

Mammography facilities must be certified by the FDA and accredited by an official organization to make sure they meet standards for personnel, equipment, and quality control. Information on qualified facilities is available from the American Cancer Society or can be accessed on the FDA Web site (www.fda.gov/cdrh/mammography/certified.html)

For more information, see the American Cancer Society document Mammograms and Other Breast Imaging Procedures.

Nuclear Scans

Other Names

nuclear imaging, radionuclide imaging, nuclear medicine scans

What Do They Show?

Nuclear scans provide images based on the body’s chemistry rather than on anatomy (as is the case with other imaging tests). They use substances called radionuclides (also known as tracers or radiopharmaceuticals) that release low levels of radiation. The small amount of radioactivity used is harmless.

Inside the body, tissues affected by certain diseases such as cancer may absorb more or less of the tracer than normal tissues. Special cameras pick up the pattern of radioactivity to create images that show where the material has traveled and where it has accumulated. The scans show certain disorders of internal organs and tissues more accurately than standard x-ray images.

If cancer is present, the tumor may show up on the image as a "hot spot" – an area of increased uptake. Depending on the type of scan performed, the tumor may instead be a "cold spot" – a site of decreased uptake.

Nuclear scans are used to locate tumors, especially in the bones and thyroid gland. They are also used to study a cancer's stage (extent of its spread) and to decide if treatment is working. In the past, nuclear scans were often used to detect liver and brain tumors. Because of improvements in technology, a CT or MRI scan can now be done instead of a nuclear scan in many of these cases.

Nuclear scans may not detect very small tumors, nor do they always distinguish between benign and malignant (cancerous) tumors. They are often used along with other imaging tests to give a more complete picture of what is going on. For example, bone scans that show "hot spots" on the skeleton are usually followed by x-rays of the affected bones, which are better at showing details of the bone structure.

Nuclear scans have different names, depending on the organ involved. Some of the more commonly used nuclear scans (described in more detail below) include:

• bone scans
• gallium scans
• FDG PET scans

How Do They Work?

The type of scan done depends on what organ or tissue the doctor wishes to study. In general you are given an oral or intravenous (IV) dose of a compound that emits small doses of radiation.

Radionuclide scans: Because they evaluate more than just the anatomy of a tumor, radionuclide scans have uses other than simply creating images. There are several radionuclides now in use:

Gallium-67 is used to detect cancer in the lungs, in lymph nodes or in bone marrow (such as Hodgkin disease or non-Hodgkin lymphoma). Gallium can also be used for a whole body scan (also called a gallium scan).

Technetium-99 is used in whole body scans, especially in bone scans that look for metastasis (spread) to bones from breast, lung, prostate, or other cancers. Technetium sestamibi (Miraluma) scans are being studied for their usefulness in breast cancer, as well as in determining the resistance of some tumors to chemotherapy.

Thallium-201 scans, more commonly used in cardiology (the study of heart disease), are sometimes used to determine the effectiveness of treatment for brain or lung tumors and may be useful for detecting lymphomas, as well as thyroid and breast cancers.

Radioactive iodine (iodine-123 or iodine-131) can be used to detect (and even treat) thyroid cancers and some neuroendocrine tumors, such as carcinoid tumors.

These substances emit gamma rays, which can be detected by a special camera (known as a gamma camera, rectilinear scanner, or scintiscan). The signals are processed by a computer, which turns them into two- or three-dimensional (3D) images, sometimes with color added for extra clarity. A radiologist or a doctor who specializes in nuclear medicine interprets the image and sends a report to your doctor.

A form of radionuclide scanning using a special gamma camera, called single-photon emission computed tomography (SPECT), has become available in recent years. It has better resolution than standard radionuclide scanning. Like a CT scan, SPECT uses a rotating camera to create 3D cross-sectional images, or "slices," of the body. However, this technique uses radioactive substances, rather than the x-rays used in CT scans. SPECT is often used to detect bone metastasis in patients with cancer.

Positron emission tomography (PET) scans: Positron emission tomography (PET)is a technique that usually involves a form of radioactive sugar known as fluorodeoxyglucose (FDG). Cells of the body absorb different amounts of the radioactive sugar, depending on how fast they are growing. Cancer cells, which grow quickly, are more likely to take up large amounts of FDG. The substance gives off tiny atomic particles called positrons, which run into electrons in the body, giving off gamma rays. A special camera detects these rays as they leave the body.

By providing data on how active the cells in the body are, PET scans can help identify which tumors are more aggressive and can distinguish tumors from normal tissue that has been affected by cancer treatment.

PET scans are especially useful for studying the brain. The technique is still fairly new but is becoming more widely used in looking at cancers of the head and neck, thyroid, esophagus, breast, colon, rectum, ovary, and lung, as well as melanomas and lymphomas.

A newer imaging machine combines PET scanning with CT scanning. PET/CT scanners provide more detailed information on the location of any increased cell activity, helping doctors to pinpoint the location of tumors.

Use of monoclonal antibodies in nuclear scans: A special type of antibody produced in the lab called a monoclonal antibody can be designed to stick to substances found only on the surface of cancer cells. A radioactive substance is attached to the monoclonal antibody, which is then given into a vein. It travels in the bloodstream until it reaches the tumor. The antibody, still carrying its radioactive cargo, attaches to the surface of the tumor. This causes the tumor to light up when viewed through a special scanner. Monoclonal antibody scanning is sometimes used to evaluate cancers of the prostate (ProstaScint^® scan), colon (OncoScint^®, CEA-Scan®), ovaries (OncoScint^®), breast, skin (melanoma), and other organs.

How Do I Prepare for the Test?

The steps to take in preparing for a nuclear scan depend on the type of test and the tissue that will be studied. Gallbladder, liver, or thyroid scans require that you don't eat or drink for 2 to 12 hours beforehand. In other cases, you may be asked to take a laxative or have an enema. You may need to avoid some medicines (prescription and over-the-counter) before the test, so be sure to check with your doctor or nurse. Your health care team will provide you with specific instructions.

The radioactive material is given by mouth or by injection into a vein, usually a few minutes or several hours before the test. For example, in a bone scan, the dose is injected about 2 hours before the test begins. You will have to drink several glasses of water to flush out any of the radioactive material that is not absorbed by the bones. For gallium scans, on the other hand, the injection is given a few days before imaging.

What Is It Like Having the Test?

A nuclear scan can be done on an outpatient basis, but because of the special materials and equipment needed, the scans are usually done in the radiology or nuclear medicine department of a hospital.

You lie on a table while the scanner moves back and forth. The technician may ask you to shift positions to allow different views to be taken. The test is not painful. However, you may become uncomfortable after lying on the table for a while.

If you are having a brain scan, several sets of images may be needed. The first scans are taken as the radioactive material moves through the arteries into the brain. The second set, taken a few hours later, reveals the presence of the material in the brain itself. You will be asked to move your head into different positions. Similarly, a thyroid scan may require 2 sets of tests using oral doses of radioactive iodine.

How Long Does It Take?

A nuclear scan takes about 30 to 60 minutes, plus the waiting time after the radioactive material is given. For bone scans, the material takes 2 to 3 hours to be absorbed, and the scan itself takes another hour or so. Gallium scans take several days between the injection and the actual scanning. Results of nuclear scans are usually available within a few days.

What Are the Possible Complications?

Generally, nuclear scans are safe procedures. The doses of radiation are very small, and the radionuclides have a low risk of toxicity or allergy. Some people may experience pain or swelling at the site where the radioactive material is injected. Using a moist, warm cloth on the area can relieve symptoms. Rarely, some people will develop a fever or allergic reaction when given a monoclonal antibody.

What Else Should I Know About This Test?

• The amount of radiation exposure from a nuclear scan is about the same as that from standard x-rays. The scanning machine itself does not emit radiation. The radioactive material used during the test is eliminated from the body within a few hours or a few days. Talk to your health care team about sexual activity or being close to children during this time.

• The day after a scan, to reduce your risk of exposure to radioactive material excreted in urine, you should flush the toilet immediately after you use it.

• Nuclear scans are not recommended for pregnant women or nursing mothers.

Ultrasound (US)

Other Names

ultrasonography, sonography, sonogram

What Does It Show?

An ultrasound machine produces images called sonograms by generating high-frequency sound waves that go through your body. As the sound waves bounce off your internal organs and tissues, they create echoes. Cysts (fluid-filled sacs) and solid tumors have different echo patterns than normal body tissues.

Ultrasound is especially good at giving pictures of some diseases of soft tissues that do not show up as well on x-rays. Ultrasound is an excellent way to tell fluid-filled cysts from solid tumors because the echo patterns produced by these disorders look very different. In diagnosing breast masses, for example, ultrasound is often used to tell cysts from solid tumors. Ultrasound can also be used to determine how deeply a tumor of the esophagus, rectum, or uterus has gone through the wall of the organ.

However, ultrasound images are not as detailed as those from CT or MRI scans. Ultrasound alone cannot distinguish a benign tumor from a cancerous one. Its use is also limited in some areas of the body because the sound waves cannot go through air (such as in the lungs) or through bone.

Doctors often use ultrasound to determine where to place a needle to obtain a biopsy (withdrawing fluid or tiny tissue fragments for viewing under a microscope). This procedure occurs in "real time" -- that is, the doctor can look at the ultrasound monitor while moving the needle and actually see the needle moving toward and into the tumor.

For some types of ultrasound exams, the transducer (the wand that produces the sound waves and detects echoes) is placed on the skin surface. The sound waves pass through the skin and reach the internal organs. In other cases, to get the best images, the doctor must use a transducer that is inserted into a body opening, such as the esophagus, rectum, or vagina.

Special ultrasound machines, known as Doppler flow machines, are able to show how blood is flowing through the vessels. This is important because blood flows differently through tumors than it does through normal tissue. Some of these machines make color images to increase the amount of information it contains. Unlike other forms of blood vessel imaging, color Doppler studies do not require contrast agents. Color Doppler has made it easier for doctors to determine if cancer has spread into blood vessels, especially in the liver and pancreas.

How Does It Work?

An ultrasound machine has 3 key parts: a control panel, a display screen, and a transducer, which looks somewhat like a microphone or a computer mouse. The doctor or ultrasound technologist passes the transducer over the part of the body being studied. The transducer emits sound waves and picks up the echoes. The computer inside the main part of the machine analyzes the signals and displays an image on a computer screen.

The shape and intensity of the echoes depend on how dense the tissue is. For example, most of the sound waves pass right through a fluid-filled cyst and send back very few or faint echoes, causing it to appear black on the display screen. But the waves will bounce off a solid tumor, creating a pattern of echoes that the computer will translate into a lighter colored image.

How Do I Prepare for the Test?

As a general rule, no preparation is needed. However, your doctor or nurse will give you specific instructions about steps to take before your test. Depending on the organ being studied, you may need to fast overnight, take a laxative, or have an enema. If you will have an abdominal ultrasound, you may need to drink a large amount of water just before the study to fill your bladder. This will create a better picture because sound waves travel better through fluid.

What Is It Like Having the Test?

Ultrasound tests can be done in a doctor's office, clinic, or hospital. You will lie down on a table. The technologist will apply a gel to the part of the skin over which the transducer will pass. The gel both lubricates the skin and enhances the transmission of the sound waves. The gel feels cool and slippery. If a probe is used, it will be covered with gel and inserted into the body opening. Such procedures are not painful, but they can cause you to feel pressure or discomfort.

During the test the technologist or the doctor moves the transducer back and forth. You may be asked to hold your breath during the scan to prevent excess movement. The operator may adjust knobs or dials to increase the depth to which the sound waves are sent. You may feel slight pressure from the transducer, but you will not hear the high-frequency sounds.

How Long Does It Take?

An ultrasound exam usually takes 20 to 30 minutes. The length of time depends on the type of exam and the ease or difficulty in finding any abnormalities of the organs being studied.

What Are the Possible Complications?

Ultrasound is a very safe procedure with a low risk of complications. Good images are harder to obtain in people who are obese.

What Else Should I Know About This Test?

• Ultrasound does not use radiation.
• Ultrasound costs much less than CT or MRI.
• The quality of the results depends to a large extent on the skill of the technologist or doctor operating the transducer, which is not the case with CT or MRI.
• Newer forms of ultrasound can provide 3D images.
• Contrast agents that may be used to enhance the quality of the picture are currently being studied.

Categories of Some Common Imaging Tests

Angiogram: see Radiographic Studies

Arteriogram: see Radiographic Studies – Angiogram

Barium enema: see Radiographic Studies – Lower GI Series

Barium swallow: see Radiographic Studies – Upper GI Series

Bone scan: see Nuclear Scans

Gastrointestinal series: see Radiographic Studies – Upper and Lower GI Series

Positron emission tomography (PET): see Nuclear Scans

Pyelography, intravenous (IVP): see Radiographic Studies

SPECT: see Nuclear Scans

X-ray: see Radiographic Studies

General Comments on Radiation Risk

In large doses, radiation can cause severe tissue damage and increase a person's risk of later developing cancer. Although the low doses of radiation used for imaging tests can increase a person's cancer risk slightly, it is important to put this risk into perspective.

How Much Does an Imaging Test Increase a Person's Yearly Exposure to Radiation?

Many people do not realize that we are constantly exposed to radiation from a variety of sources, including radioactive materials in our environment and cosmic rays from outer space.

The average person is exposed to about 3 millisieverts (mSv) of radiation from natural sources over the course of a year. (A millisievert is a measure of radiation exposure.) Much of this is due to radon, a naturally occurring gas whose levels vary across the country. Because the earth's atmosphere blocks some cosmic rays, living at a higher altitude increases a person's exposure. For example, residents in Denver, Colorado have an annual exposure level of about 5 mSv. A round-trip airline flight across the United States increases exposure by about 0.03 mSv.

A single chest x-ray exposes the patient to about 0.1 mSv, which is about the radiation dose people are exposed to naturally over the course of about 10 days. Some other imaging tests involve higher exposures. A lower GI series exposes a person to about 4 mSv while a CT scan of the abdomen exposes a person to about 10 mSv. (MRI and ultrasound exams do not expose a person to radiation.)

How Much Does the Additional Radiation Exposure Increase a Person's Cancer Risk?

Unfortunately this is a hard question to answer. Most studies on the subject have looked at people exposed to higher doses of radiation, such as uranium miners and atomic bomb survivors. The risk from low-level radiation exposure is not easy to calculate from these studies. Researchers have estimated that radiation exposure from the average diagnostic x-ray may increase cancer risk very slightly (likely on the order of hundredths to thousandths of one percent). Of course, this can be affected by the type of test done, the area of the body exposed, and other factors.

Because of this very small but real effect, and the fact that radiation exposure from all sources can add up over one’s lifetime, imaging tests involving radiation should not be done without a valid medical reason. In many cases, other imaging tests such as ultrasound or MRI that do not involve radiation may be used. But when there is a reason to believe that an x-ray test or CT scan is the best way to diagnose cancer or other diseases, the benefit to the patient is virtually certain to exceed the risk posed by the small dose of radiation.

How Imaging Tests Are Used in Specific Cancers

Many different methods are used to obtain images, including x-rays, ultrasound, magnetic resonance imaging (MRI), nuclear medicine scans, and so on. The approach your health care team recommends may depend on a number of factors:

• the location and type of the tumor; some imaging studies work better for certain organs or tissues
• if a biopsy (tissue sample) is needed
• the balance between any risks or side effects and the potential benefits
• the costs

The following table lists the imaging tests that may be used for various types of cancers. Other types of tests, such as endoscopy (inspection of body organs or cavities using a flexible, lighted tube), may be used in addition to or in place of those listed. Tests are chosen based on the extent and type of cancer. If you have questions about a test that your health care team has advised for you, ask them to explain the purpose of the test.

Table 2: Common Uses of Imaging Tests in Oncology

Bladder and Ureter

Detection:	Intravenous pyelogram
Staging:	MRI or CT of pelvis Chest x-ray

Breast

Screening:	Mammogram (screening) Ultrasound or MRI (together with mammogram in some younger women or those with dense breast tissue)
Detection:	Mammogram (diagnostic) Ultrasound (distinguish solid masses from cysts) MRI Nuclear scans (under investigation)
Image-guided biopsy:	Stereotactic mammography Ultrasound
Staging:	Chest x-ray Nuclear scan (bone scan) CT or MRI of abdomen and/or head

Brain & Spinal Cord

Detection:	MRI (usually preferred) CT
Imaging-guided biopsy:	CT
Staging:	CT or MRI

Colon and Rectum

Screening:	Lower GI series (barium enema with air contrast)
Detection:	Lower GI series (barium enema with air contrast)
Staging:	Chest x-ray CT of abdomen and chest Ultrasound (with rectal probe to check depth of rectal cancer invasion) MRI (rectal cancer)

Endometrium (Lining of Uterus)

Staging:

MRI (Usually surgery is performed for primary staging of the cancer; but MRI provides added information about involvement of lymph nodes) Ultrasound with vaginal probe (to estimate depth of invasion within uterus)

Esophagus

Detection:	Upper GI series (barium swallow)
Staging:	Ultrasound with esophageal probe (to estimate depth of tumor invasion and assess nearby lymph node involvement) CT of chest and abdomen

Head and Neck

Staging:

CT or MRI (evaluate size of tumor and spread to nearby soft tissue, bone, blood vessels, etc.)

Kidney

Detection:	Intravenous pyelogram
Staging:	CT Chest x-ray CT of abdomen and chest MRI (to check for cancer spread into nearby veins)

Liver

Detection:	CT MRI Ultrasound
Image-guided biopsy:	CT Ultrasound
Staging:	CT MRI

Lung

Detection:	Chest x-ray CT
Image-guided biopsy:	CT Fluoroscopy (continuous x-ray)
Staging:	CT of chest, head, abdomen MRI

Non-Hodgkin Lymphoma & Hodgkin Disease

Detection:	CT MRI
Image-guided biopsy:	Ultrasound CT
Staging:	CT MRI Lymphangiogram (rarely done)

Soft Tissue (Muscle, Tendons, Fat)

Detection:	CT MRI
Image-guided biopsy:	CT
Staging:	CT of chest, head, abdomen

Ovary

Detection:	Ultrasound MRI CT
Staging:	CT, MRI, or PET may be done before surgery. Staging is done during surgery.

Pancreas

Detection/diagnosis:	CT MRI Ultrasound
Image-guided biopsy:	CT
Staging:	CT

Prostate

Detection:	Ultrasound with rectal probe
Image-guided biopsy:	Ultrasound with rectal probe
Staging:	Bone scan CT or MRI Monoclonal antibody nuclear scan (ProstaScint)

Stomach

Detection/diagnosis:	Upper GI series (barium swallow with double contrast)
Staging:	Ultrasound CT Chest x-ray

Thyroid

Detection/diagnosis:	Nuclear medicine scans
Image-guided biopsy:	Ultrasound
Staging:	Nuclear medicine CT

CT = Computed tomography
MRI = Magnetic resonance imaging
PET= Positron emission tomography
GI = Gastrointestinal

Screening tests refer to procedures used to find a disease, such as cancer, in people who do not have symptoms of that disease.

Detection refers to diagnostic procedures used if you have some indication (such as symptoms, abnormal physical exam results, or abnormal results from screening tests) that a disease such as cancer may be present. Imaging tests for detection can help find a mass or other abnormality of tissue and can often predict whether it is likely to be a cancer or some other type of disease. However, in almost all cases, a tissue sample (biopsy) must be viewed under the microscope to be sure if a cancer is present.

Image-guided biopsy refers to use of imaging tests to help guide a biopsy needle into the area of abnormal tissue. An image-guided biopsy can often provide tissue for study without the need for surgery.

Staging is the process of determining how far a cancer has grown and spread. Imaging tests are often used to estimate the size of a cancer; to find out how far it has spread in the organ in which it started; and to see whether it has spread to nearby tissues and organs, nearby lymph nodes, or distant organs. Most of the tests listed in this section are used to look for metastases in distant organs or tissues. For instance, men with prostate cancer often have bone scans to see if the cancer has spread to bones.

Selection of imaging tests for staging will depend on the doctor's impression of how far the cancer is likely to have spread, as well as symptoms. People with larger cancers and those that have already spread to lymph nodes may need tests such as nuclear scans, CT scans, or MRI to look for distant metastases. People with bone pain, neurologic symptoms (such as numbness, paralysis, problems with balance or coordination, etc.), or other symptoms suggesting distant metastasis will have more extensive evaluation by imaging tests. On the other hand, these tests may not be done in people without symptoms of metastasis who have small tumors that appear localized.

Additional Resources

More Information From Your American Cancer Society

The following information may also be helpful to you. You may view these materials online or order them from our toll-free number, 1-800-ACS-2345 (1-800-227-2345).

• A Message of Hope: Coping With Cancer In Everyday Life (also available in Spanish)
• After Diagnosis: A Guide for Patients and Families (also available in Spanish)
• Choosing a Doctor and a Hospital
• Endoscopy
• Health Professionals Associated With Cancer Care
• Mammograms and Other Breast Imaging Procedures
• Testing Biopsy and Cytology Specimens for Cancer

References

American College of Radiology/Radiological Society of North America. RadiologyInfo. Available at: www.radiologyinfo.org. Accessed November 22, 2005.

Hricak H, Akin O, Bradbury MS, et al. Advanced imaging methods: Functional and metabolic imaging. In: DeVita VT, Hellman S, Rosenberg SA, eds. Cancer: Principles & Practice of Oncology. 7th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2005:589-720.

Little JB. Ionizing radiation. In: Kufe DW, Pollock RE, Weichselbaum RR, Bast RC, Gansler TS, Holland JF, Frei E, eds. Cancer Medicine. 6th ed. Hamilton, Ontario: BC Decker; 2003:289-301.

U.S. Department of Energy. Radiation in Perspective. 2003. Available at: www.eh.doe.gov/radiation/Radiation-final-6-20.pdf. Accessed November 23, 2005.

Revised: 09/07/2007