X-rays and other radiographic examinations aid doctors in the detection of cancer in various sections of the body, including the bones and organs such as the stomach and kidneys. X-rays are usually quick and painless, and no special preparation is required. Contrast studies may necessitate more preparation ahead of time and may result in discomfort and side effects, depending on the type.
What do they show?
Radiographs (also known as x-rays) provide shadow-like images of bones, organs, and tissues. X-rays are quite effective at detecting bone abnormalities. Although they can show some organs and soft tissues, MRI and CT scans frequently provide better images. Still, because x-rays are quick, easy to obtain, and less expensive than other scans, they may be employed to obtain information quickly.
Breast x-rays (mammograms) are a type of radiographic test.
Contrast studies are x-rayed tests that use iodine-based dyes or contrast materials, such as barium, in conjunction with the x-rays to make the organs show up on the x-ray and obtain better images. For example, after the intestine is filled with barium sulfate, a lower gastrointestinal (GI) series, often known as a barium enema exam, obtains x-ray photos. An intravenous pyelogram (IVP) is a contrast study that employs a specific dye to examine the structure and function of the urinary system (ureters, bladder, and kidneys).
Many contrast investigations are being replaced by other scans, such as CT or MRI, as a result of technological advancements. For example, angiography was once commonly used to determine the stage or extent of cancer, but now CT and MRI scans are more commonly employed. Angiography is still sometimes used to visualize the blood arteries near the malignancy so that surgery can be planned to minimize blood loss. Angiograms can also be used to diagnose illnesses of the blood vessels that aren’t malignant.
How do they work?
A controlled beam of radiation is sent out by a specific tube inside the x-ray equipment. Radiation is absorbed or blocked to variable degrees by biological tissues. Soft tissues, such as fat and muscle, block less radiation than dense tissues like bones. The laser hits a piece of film or a specific detector after traveling through the body. Bone and other tissues that block a lot of radiation appear as white spots on a black backdrop. Soft tissues absorb less radiation and appear in greyscale. Organs that are largely made up of air, such as the lungs, usually appear black. Tumors are typically denser than the surrounding tissue, therefore they appear in lighter colors of grey.
Contrast studies can provide information that traditional x-rays couldn’t. During a contrast study, a contrast substance is applied to the body to define, highlight, or fill in portions of the body so that they appear more clearly on an x-ray. The contrast substance can be administered orally, as an enema, intravenously (into a vein), or by a catheter (a tiny tube) inserted into various body tissues. On an x-ray, it will appear bright white and outline the bodily portion. The images for most of these tests can be taken on x-ray film or by a computer.
How do I get ready for the test(s)?
Aside from removing any metal objects that can obstruct the image, no extra preparation is required before undergoing a normal x-ray.
The amount of time it takes to prepare for a contrast study is determined by the test. Before the test, you may be asked not to eat anything or to prepare in various ways (see the next section). You will be given instructions by the radiology center. First, double-check with them. You may also receive instructions from your health care practitioner.
Always tell your doctor if you have any iodine sensitivities or if you’ve had any problems with contrast materials in the past.
What is it like having the test(s)?
X-rays are typically taken by an x-ray technologist. To expose the part of the body that will be x-rayed, you will undress. You’ll need to take off any jewelry or anything that can obstruct the image. It’s possible that you’ll be given a robe or drape to wear. Depending on the body part to be x-rayed, you will be asked to sit, stand, or lie down. The x-ray film is placed against your body in a flat box or table. The technologist then rotates the machine to direct the radiation beam to the correct location.
For a chest x-ray, often 2 views are taken. First, you stand with your chest against the x-ray film, and the image is taken from the back. Your arms are at your side. Then a side view is often taken with your arms either above your head or in front of you. The technologist will tell you when to take a deep breath and hold still. For a chest x-ray in people who can’t stand, the film is put under them and the picture is taken from the front.
During an abdominal (belly) x-ray, you lie down on a table. You may be asked to change position or sit up if more than one view is needed. You’ll need to hold your breath and lie still while the picture is taken quickly.
After the x-ray, the technologist will come back 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: You’ll be asked to not eat before this test. In most cases, you’ll be given medicine to relax you before the test starts. You will lie still on a table as the skin over the injection site is cleaned and numbed. A tiny cut will be made so the catheter (thin plastic tube) can be put into a blood vessel (usually the artery at the top of the thigh) and slid in until it reaches the area to be studied. The contrast dye is then put in, and a series of x-ray pictures are taken to see how the dye flows through the blood vessels. After that, the catheter is taken out.
Firm pressure might be needed on the catheter site for a while to make sure it doesn’t bleed. You’ll also need to lie flat and keep your leg still for up to several hours. This helps prevent bleeding at the catheter site, too.
Other types of angiography: Advances in technology have led to other forms of angiography that take less time and mean fewer risks than x-ray angiography. CT angiography takes pictures of blood vessels using a CT scanner instead of a standard x-ray machine. The contrast dye can be put into a small vein in the arm instead of having to put a catheter into a major blood vessel. Magnetic resonance angiography (MRA) is an MRI study of the blood vessels. It may be done with or without contrast dye and is also quicker than a standard x-ray angiogram.
Intravenous pyelogram (IVP): You’ll probably be asked not to eat or drink anything for about 12 hours before this test, and you must take laxatives to clean out your bowel. For the test itself, you lie on a table for a series of x-rays. Contrast dye is then put into a vein in your arm. Your kidneys remove the dye from the bloodstream, and it goes into the urinary tract. Another series of x-rays is taken over the next 30 minutes or so to get pictures of the dye as it moves through the kidneys and out of your body. Pressure may be applied to the belly to help make the image clearer. Once the dye has reached the bladder, you’ll be asked to pass urine while another x-ray is taken.
Lower GI series (barium enema): Your diet may be restricted for a few days before this test. Laxatives and/or enemas are used to clean out the bowel (large intestine). For the test, you lie down and are strapped to a table. A series of x-rays are taken. Then liquid barium is put into your bowel through a small, soft tube placed in your rectum. The liquid feels cool. More images are then taken while the table tilts you into different positions. This helps the barium move through your bowels so they can be seen on the x-rays. You have to lie still and hold your breath as each image is taken.
After the test, you can go to the toilet to pass the barium solution out of your bowels. (It may take a few days until it’s all out. Your stool may be drier, harder, and light-colored during this time.)
To get clearer pictures, a “double-contrast” exam is often done. This exam uses a smaller amount of thicker barium liquid. After the barium is in, the air is put into your bowel. This can cause a sense of fullness and discomfort, along with an urge to empty your bowels.
Upper GI series: You will probably be asked to not eat or drink for 8 to 12 hours before this test. You will lie down and be strapped to a tilting table while a series of x-rays are taken as the barium coats your esophagus and stomach. You’ll need to swallow the barium mixture a few times during the test. (In some cases, substances other than barium are used.) You might also be asked to swallow baking soda crystals to create gas in your stomach.
A few hours later, further photos are obtained to reveal the small intestine (it takes time for the barium to move from the stomach to the small intestine). A tiny bowel follow-through is what it’s called.
You may be given a laxative after the test to help get the barium out of your system faster. It could take a few days to clear everything out. During this time, your stool may become drier, firmer, and lighter in color.
Venography: As you lie still on a table, the skin over the vein to be used is cleaned and numbed. This will be a small vein below the vein that might be blocked (like the foot for a vein in the leg, or the hand for a vein in the arm). A catheter (thin plastic tube) is then put into the small vein. It may be threaded in so that it passes into a larger vein closer to the one to be studied, or a tourniquet may be used so the dye flows into the deeper veins. The contrast dye is put in to make the veins show up on the x-ray, and a series of x-ray pictures are taken.
Extra fluids may be given through the catheter to help wash the dye out of your body. After that, the catheter is taken out. Firm pressure may be needed on the site for a while to make sure it doesn’t bleed.
How long do they take?
- Standard x-ray: about 5 to 10 minutes
- Angiogram: 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
- Venogram: 30 to 90 minutes
What are the possible complications and side effects of these imaging tests?
Standard x-rays: Problems are rare and 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 can have a severe allergic reaction to the contrast material that affects their breathing and blood pressure. The contrast material can also cause kidney problems. This is rare, but it’s more common in someone whose kidneys already don’t work well.
There’s a chance that a blood clot will form on the catheter’s tip, which could obstruct a blood vessel. There’s also a chance that the catheter will injure the blood vessel, resulting in an internal hemorrhage. If the catheter is not kept in place for a long enough time, a hematoma (a big collection of blood under the skin) may form. At the catheter site, infection is a possibility. (Complications from CT or MR angiography are similar to those mentioned in the CT and MRI sections.)
Your body may ache from lying still on the flat table for a few hours.
Intravenous pyelogram (IVP): The contrast dye sometimes causes some people to have flushing, mild itching, or a bitter or salty taste. In rare cases, people have a severe reaction to the contrast material and need emergency treatment.
Lower GI series (barium enema): The test can be uncomfortable. Some patients have abdominal (belly) cramping. Many patients find the test makes them tired. The barium contrast material will make your stools a light color for a few days after the test and may cause constipation. Very rarely, the barium can cause an obstruction, or blockage, in the bowels.
Upper GI series (barium swallow): The barium mixture has the thickness of a milkshake and tastes chalky. Baking soda crystals can cause bloating, gas, and belching. After the test, your stools will be a light color for a few days, and you may be constipated. There’s a slight chance that the barium might cause an obstruction or blockage in the intestine.
Venography: You may have a warm or burning feeling as the dye is given. Your arm or leg (where the catheter is put in) may feel numb during the test. Some people have a bitter or salty taste in their mouths. In rare cases, people can have a severe allergic reaction to the contrast material that affects their breathing and blood pressure. The contrast material can also cause kidney problems. This is rare, and it’s more common in someone whose kidneys already don’t work well.
There’s a small risk of a blood clot forming, which could block a blood vessel. There’s also a small risk of damage to the blood vessel from the catheter, which could lead to internal bleeding. There may be pain and bruising and infection is possible where the catheter is put in.
What else should I know about these tests?
- Before undergoing any of these tests, inform your doctor if you are pregnant or breastfeeding.
- Although x-ray tests expose the body to radiation, modern x-ray equipment emits far less radiation than older technology. (For more information, see “Understanding Radiation Risk from Imaging Tests.”)
- Digital radiology is a modern technology that produces images on computer displays rather than film. The images can be digitally changed in size and contrast to make them easier to view, and they can also be transferred to computers at other medical offices or hospitals.
- If you are to have a test that uses a contrast dye, tell your doctor if you are allergic to contrast materials, iodine, or seafood. This may put you at a higher risk of having a reaction.