Imaging tests are procedures that produce images of internal body organs, tissues, structures and pathways. They may be used in the diagnosis of health conditions and the management of disease. Imaging tests may also be used to assist certain procedures and surgeries.
The most commonly used imaging tests for diagnosing conditions in children include:
X-ray. A test in which an image is created of bones, joints and internal organs by using low doses of electromagnetic radiation that are reflected on film paper or fluorescent screens.
CAT scan (computed axial tomography). Also known as a CT scan, it is a noninvasive and painless test that uses a rotating x-ray device to create detailed cross-sectional images (or slices) of organs, bones and other body parts.
MRI (magnetic resonance imaging). A noninvasive procedure that uses powerful magnets and radio waves to produce clear, cross-sectional or three-dimensional images of the body’s tissues, even through bone and other obstructions.
Ultrasound. Also known as sonogram, this noninvasive test uses high-frequency sound waves to create images of the shape and outline of various tissues and organs in the body.
Nuclear medicine scans. A subspecialty of radiology that uses radioactive substances and a special tool called a gamma camera to create images of organ systems in the body.
A radiology technician in a hospital or outpatient clinic generally performs imaging tests. Patient preparation differs depending on the nature of the test to be performed. In some instances, a child may need to drink or be injected with a dye known as a contrast medium. This solution makes certain organs and tissues in the body more visible. The imaging test procedures are different depending on which test is performed. Generally, children are able to return home the same day of the test.
Imaging tests carry very few risks to the child. Though imaging tests are the same for adults and children, tests of children are likely to incorporate lower dosage levels of radiation or radiopharmaceutical agents.
Imaging tests are more likely to frighten children than adults. Many hospitals have staff who either work exclusively with children, or have a lot of experience with younger patients. These healthcare professionals are skilled in calming a child’s fears. Some hospitals have pediatric radiology programs to make children feel more comfortable during these procedures.
About imaging tests
Imaging tests produce pictures of internal body organs, tissues, structures and pathways. Some tests can be performed with external devices. Other tests (e.g., endoscopy) require that a device be inserted into a body opening.
Imaging tests are used in the diagnosis of conditions and the management of disease. They may also be used to assist certain procedures and surgeries. In some cases, a dye known as a contrast medium is used as part of an imaging test. This solution contains a liquid that makes certain organs and tissues in the body more visible by highlighting the structure. This helps reveal the presence of disease or injury.
There are several types of imaging tests that can be used to view internal structures of a child’s body. The tests most widely used in diagnosing conditions in children include x-rays, CAT scans (computed axial tomography), MRI (magnetic resonance imaging), ultrasound and nuclear medicine scans.
X-rays are the oldest form of imaging test. In this procedure, an image is created of part of the body by using low doses of electromagnetic radiation that are reflected on film paper or fluorescent screens. The absorption of x-rays differs depending on the type of tissue being x-rayed. Bones absorb x-rays and appear white, soft tissues pass more x-rays and appear gray, and tissues containing air (e.g., lungs, intestines) appear dark. X-rays can be used in diagnosis of a wide range of conditions including bone breaks, chips and fractures; sprains and strains; and tooth or jaw pain. X-rays also are used to look for objects that a child is believed to have swallowed (e.g., coins).
Other conditions in children that can be diagnosed or monitored using x-rays include:
Abdominal pain
Artery blockages
Bone infections and joint injuries
Coughing and chest pain
Degenerative conditions, such as arthritis
Heart and lung disorders
Sinus infection (sinusitis)
Spinal problems such as scoliosis (abnormal curvature of the spine)
A CAT scan, also known as a CT scan, is a noninvasive and painless test that uses a rotating x-ray device to create detailed cross-sectional images (or slices) of different body parts. It may be performed alone or with the use of a special dye (contrast medium).
In children, CAT scans are typically used to diagnose abdominal pain, birth defects, changes related to injuries, headaches, infectious or inflammatory disorders and cancer.
CAT scans are also used to monitor treatments to see if they are effective in reversing various diseases, and to analyze blood vessels in the brain, face or neck. Children who have suffered a head injury may undergo a CAT scan so a physician can determine whether there is bleeding within the brain or other damage. Other conditions in children that may be diagnosed with CAT scans include:
Conditions affecting the spinal cord and the bones that make up the spinal column.
Chest conditions, including complications from pneumonia and other infections, tumors in the lungs, inflammation of the bronchi and other airway diseases, and birth defects, such as pectus excavum (also referred as funnel chest, in which the sternum [breastbone] is abnormally depressed).
Diseases of the abdominal organs, including the liver, kidney and spleen. Other abdominal disorders that may be detected with a CAT scan include appendicitis, inflammatory disorders of the bowel (including colitis), abdominal tumors, and birth defects.
Pelvic region disorders, including cysts or tumors of the ovary, bladder abnormalities, stones in the urinary tract and diseases of the pelvic bones.
MRI is a safe and painless test that produces clear, cross-sectional or three-dimensional images of the body’s tissues, even through bone and other obstructions. Because of its safety and clarity, the MRI is a valuable tool that can aid in the diagnosis of a wide range of conditions in nearly every part of the body, particularly in the brain, neck, spinal cord and soft tissues. Central nervous system disorders such as multiple sclerosis are often diagnosed using MRI. Other conditions that can be diagnosed with an MRI include.
Blood vessel blockages
Bone and joint damage
Brain tumors
Neurofibromatosis
Seizures
Damage from heart disorders
Eye abnormalities
Inner ear abnormalities
Lung, liver, pancreas, kidney and spleen disorders
Pituitary gland diseases
Reproductive system and bladder problems
Ultrasound is a test that uses high-frequency sound waves rather than radiation to create images of internal organs or tissues. In an ultrasound test, a small wand-like instrument called a transducer is passed over the child’s body as it sends low-energy sound waves against tissue. Some waves pass through and others bounce back. As sound waves bounce back, they are recorded and displayed on a computer screen or television-type monitor.
The image created by an ultrasound is considered to be less clear than those from CAT scans and MRIs. However, it is often used for a wide array of procedures since it is fast, painless, generally noninvasive and relatively inexpensive. In addition, many children are less intimidated by the wand used in this procedure than they are by the enclosed tunnels used in CAT scans and MRIs.
Ultrasound is typically used to diagnose conditions that affect abdominal organs, including the:
Appendix
Bladder and kidneys
Gallbladder
Intestines
Liver
Pancreas
Spleen
Ultrasound is used to locate stones, abscesses, or an inflamed appendix or other abdominal organ. Ultrasound is also sometimes used to guide needles into the body so that samples can be taken from abdominal organs for laboratory analysis (biopsy).
Although ultrasound is extremely safe and can be effective in diagnosing many conditions, it is not able to penetrate bone or reveal conditions in the bone. In addition, ultrasound is not always effective at imaging the stomach, small intestine or large intestine because it does not pass through air and may be obscured by gases in these areas of the body.
Nuclear medicine is a subspecialty of radiology that uses tiny amounts of radioactive substances and a special tool called a gamma camera to create images of the body’s interior. This technique is used to evaluate disorders that affect the function of the kidneys, liver, heart, lungs and bones. For example, a nuclear scan may be used to detect and diagnose urinary blockage of the kidney, bone disorders, gastrointestinal bleeding and tumors throughout the body.
Although the concept of nuclear medicine may frighten some parents, the procedure is considered to be extremely safe. It has been used for more than 30 years on children of all ages, including newborns. There is no evidence that nuclear medicine causes any long-term harm to children.
Other common imaging tests include:
Voiding cystourethrogram. Used for examining a child’s bladder and lower urinary tract. During this test, a catheter is inserted through the urethra (tube that carries urine from the bladder out of the body), into the bladder to fill it with a water-soluble contrast material. Several x-ray images of the bladder and urethra are taken as the child voids the bladder.
A voiding cystourethrogram can be used to detect abnormalities in the flow of urine through the urinary tract. The exam may be recommended after a urinary tract infection to check for a condition known as vesicoureteral reflux (VUR), when the valve or the ureters allow urine to flow backwards.
Endoscopy. A procedure that uses a flexible tube with a camera called an endoscope to examine structures inside a child’s body. Examples include colonoscopy (examines the entire large intestine, including the rectum) and gastroscopy (examines the stomach).
Lower gastrointestinal (GI) barium tests. Used to diagnose conditions that affect the large intestine. The procedure is sometimes called a barium enema (enemas involve fluid put into the rectum) because a thick liquid called barium is used to highlight the region on x-rays. This test is not painful, but can cause discomfort.
Upper gastrointestinal (GI) tests. Used to help diagnose disorders of the upper and middle portion of the digestive tract (e.g., esophagus, stomach and duodenum). During these tests, the child drinks a thick, white liquid containing barium, which coats the digestive tract and highlights the area on x-rays.
Childhood issues with imaging tests
The imaging tests that are used to generate pictures of a child’s body are the same types of procedures used for adults. However, dosage levels of radiation or radiopharmaceutical agents are likely to be lower in children than in adults because of a child’s smaller body size.
Imaging tests such as x-rays and CAT scans use radiation to generate images. This concerns many parents, who are afraid that their children will develop cancer due to radiation exposure. However, the levels of radiation used in modern imaging tests are very low, and most experts consider these tests to be very safe. Technicians always use the lowest dosage level necessary to generate an image. Nonetheless, imaging tests involving radiation should not be done without a valid medical reason.
Improvements in imaging test technology are making these tests more comfortable and less intimidating for younger patients. For example, CAT scans used to make a series of stop-and-start clanging noises that frightened many children. However, now these scans are performed in a more continuous motion that produces just slight whirring noises.
Despite these changes, many children remain intimidated by these tests. Parents are urged to discuss the procedures with their children beforehand and to explain what may take place. For example, tests such as nuclear medicine scans may involve the use of a needle to inject a radiopharmaceutical agent into a vein beforehand. Knowing what to expect may help alleviate a child’s fears.
Parents are also urged to try to answer any questions the child may have about the upcoming procedure. In some cases, parents may want to ask if they can remain in the room with the child while the test is being conducted, which can be very reassuring to the child. In cases where radiation is being used, parents may have to wear special clothing as an extra precaution against exposure to mild radiation.
Many hospitals have staff who either work exclusively with children, or have a lot of experience with younger patients. These healthcare professionals are skilled in calming a child’s fears. Some hospitals’ pediatric radiology programs are specifically designed to make children feel more comfortable during these procedures.
For example, DVDs and toys may be available to help children pass the time and to keep their minds occupied during the procedure. In some cases, equipment may be specially designed to be less intimidating to children. Parents are urged to ask their child’s pediatrician about local facilities offering these services.
Before the imaging test
Parents and children are urged to follow all preparatory steps recommended by the physician prior to the imaging test. Parents are urged to talk to their child about what is required during the procedure. For example, it is crucial that children remain very still during tests such as a CAT scan if the test is to be successful. Therefore, it is important children understand that it is better to let the medical staff know if they feel discomfort rather than to fidget during the test.
Both the physician and the technician should be informed about any implanted metal or electronic devices, such as prostheses and pacemakers. Immediately before the test, children may be asked to change into a hospital gown. All metallic objects, such as watches and jewelry, should be removed so they do not interfere with test results. In fact, children may want to leave these objects at home on the day of the test. Infants or children receiving the test may be given a sedative in some circumstances to ensure they are relaxed and remain still during testing.
If a dye or other contrast medium is to be used, the child may be instructed not to eat or drink for several hours before the test.
Contrast mediums may be administered orally (by mouth), through an enema (fluid put into the rectum) or catheter (small tube inserted into the urethra) or injected into a vein. Injection of the dye may produce a warm, flushed feeling for several minutes or a metallic taste in the mouth. Both sensations are normal and disappear quickly.
Children undergoing a nuclear scan may receive an injected or oral radiopharmaceutical agent anywhere from a few minutes to several days before the actual procedure, depending on the type of scan. The agent travels to and remains in a particular body area and releases gamma rays that are detected and imaged by the gamma camera.
During and after the imaging test
Imaging tests are generally performed by a radiology technician in a hospital or outpatient clinic. The manner in which the test unfolds will depend upon the imaging procedure being used. It is typically important for patients to hold their breath at certain points during some of these imaging tests (e.g., CAT scan). This helps create a clearer image. However, this may be difficult for children younger than age 6. As a result, younger children may simply be asked to breathe quietly and regularly throughout the test.
During an x-ray, the child will sit, stand or lie down between the x-ray machine and x-ray film. The x-ray machine is then pointed at the area being examined. Multiple x-rays may be taken from different angles if necessary.
During a computed axial tomography (CAT) scan, the child lies down and remains still on a scanning table, which slides slowly into a short, open-ended tunnel. The x-ray sensing unit and detectors then rotate around the body as images are captured.
During MRI (magnetic resonance imaging), the child is placed on a long bed that slides into the MRI chamber. The MRI equipment will make many different types of noises during the scan as it takes multiple views of the target site. These noises are a normal part of the MRI procedure.
During an ultrasound, a small amount of water-soluble gel (to help transmit the sound waves) is placed on the part of the body to be tested. The technician places a wand-like instrument called a transducer on the part of the body to be scanned. In some tests, a probe transducer may be placed within an opening, such as the vagina or anus. The sound waves sent from the transducer bounce off the structures within the body and the information is deciphered by the computer to create the ultrasound images. The ultrasound images then appear on the television monitor and the moving pictures can be recorded on videotape.
During a nuclear medicine scan, the child lies on a scanning table while a gamma camera moves around them and obtains images.
Imaging tests can take anywhere from a few minutes to several hours to complete, depending on the nature of the test and the part of the body to be examined. Most imaging tests are painless.
In many cases, children undergoing imaging tests should be able to leave the facility immediately following the imaging test with no side effects. However, if a sedative is administered, children will be monitored at the facility until the effects of the sedative have passed.
After the imaging test is performed, the radiologist or physician will analyze the images. The results will then be reported to the parent or the child.
Potential risks with imaging tests
Imaging tests are generally safe and present few risks to the child. The levels of radiation used in these tests are very low and experts believe that they pose very little risk of long-term harm.
Still, exposure to any level of radiation has the potential to damage tissue, which in some cases may eventually result in cancer. It is important for parents to weigh the potential risks against the potentially life-saving benefits of the information obtained from the test.
As a precaution, some older children may be asked to wear a lead apron to shield reproductive organs from exposure to radiation. At very high doses, radiation can damage a girl’s eggs or a boy’s sperm.
In rare cases, the special dye (contrast medium) used during a CAT scan may cause nausea, a metallic or bitter aftertaste in the mouth, feeling of flushing or warmth or an allergic reaction in the form of mild itching or hives (small, raised, reddened areas of skin). In more severe reactions, shortness of breath, wheezing and swelling of the throat or other body areas that require treatment with allergy medication (e.g., epinephrine) may occur. Children or parents who notice any of these symptoms developing during the procedure should immediately alert the technician performing the test.
Parents or caregivers should also inform the physician of the following conditions in their child before imaging tests are performed:
Asthma or allergies. Contrast mediums can produce allergic reactions in some people, especially those with a history of asthma or allergies.
Other medical conditions. Certain medical conditions may also increase the likelihood of an allergic reaction to contrast mediums. These include diabetes, heart disease, kidney problems and thyroid conditions.
MRI tests should not be performed on patients with pacemakers and other types of implanted devices. If the MRI involves injection of a contrast medium, there is the possibility of a reaction. An individual may experience nausea, headache or pain at the site of injection. These symptoms are less common with MRI contrast agents than with those used for CAT scans.
Ultrasounds are considered to be extremely safe and have no significant side effects when performed properly. In extensive studies, no risks associated with properly conducted medical ultrasound have been documented. Unlike x-rays, there is no exposure to radiation during an ultrasound. This test is typically a noninvasive procedure that is widely available, easy to use and causes little patient discomfort. However, ultrasound images are not as detailed as those from CAT or MRI scans.
Questions for your doctor on imaging tests
Preparing questions in advance can help parents and children have more meaningful discussions with physicians regarding the child’s conditions. Parents and children may wish to ask their doctor the following questions related to imaging tests:
Why do you recommend an imaging test for my child?
Which type of imaging test is best to diagnose my child’s condition? Why?
Can you explain the procedure to me in detail?
What information will my child’s imaging test provide?
How should I prepare my child for the imaging test?
Will a contrast medium be used during my child’s imaging test?
Will the imaging test cause my child any pain or discomfort?
Will my child need to take a sedative for the discomfort?
Is there a local facility that specializes in performing these tests on children?
