CT Scan (Computed Tomography)
CT scans obtain multiple cross-sectional images of the body by using special X-rays and computer enhancement, creating an image many times more sensitive than from a simple X-ray. Here's how it works. The body is X-rayed from many angles, and the X-rays are then analyzed by a computer. The computer takes the images and creates a picture of the body, which can be looked at on a monitor or printed out as a photograph. The images are a composite "slice" of the body, usually the head, chest, or abdomen. The bones are also sometimes scanned. CT scans also are called CAT scans.

How is a CT done?
The child lies flat on a movable table that is guided into the center of the CT scanner. The scanner looks like an oversized doughnut. The child remains still while the X-rays are beamed into the body, then detected and fed into a computer. If the child is unable to hold still, sedatives are administered. Sometimes a dye or other contrast material is used to show the blood vessels.

How long will it take to get results?
Results are interpreted by radiologists and then reported to your physician, who will need to analyze and interpret them for you.

Echocardiography
This procedure uses a special device to detect the sound that is reflected from a beating heart. Sometimes it's called "diagnostic cardiac ultrasound" because it uses reflected sound waves to "look" directly at your child's heart. This test can show if your child has ailments such as congenital heart defects, fluid around the heart, valve disorders, or weakened heart muscles.

The device uses an "echo" of the heart ("cardio") to produce an image of a graph ("gram"). And you can actually see the heart in action as the images are projected on a monitor. The direction of blood flow into and out of the heart can be seen in different colors on the monitor.

How is an echocardiogram done?
The child lies on his back, tilted slightly to the side. A special jelly is applied to the skin on the area of the heart, and a wand (the transducer) is positioned over the heart. Sound waves are generated and reflected back to the transducer, and an image becomes visible on a monitor. Printouts are then made from the screen. There is no radiation, and the child experiences no discomfort.

How long will it take to get results?
Images are collected instantly but must be interpreted by a doctor, usually a cardiologist. Results will be reported to your physician, who will interpret them for you.

MRI (Magnetic Resonance Imaging)
Another way to take pictures of the inside of the body, MRI uses magnetism and radio waves. It also produces much more detailed images than X-rays because of its ability to separate different types of soft tissues.

MRI uses the magnetic properties of the nuclei of the atoms in the body. When radio waves are sent to a specific part of the body, the atoms emit their own radio waves, or energy. This energy is detected, and a computer translates the energy into images. MRI can be used to look at any area of the body, and is especially useful in diagnosing disease within the soft tissues of the head, spinal cord, kidneys, urinary tract, pancreas, and liver. MRIs are also the procedure of choice to detect sports injuries involving tendon and ligament damage.

How is an MRI done?
After removing any metal objects on the body, such as jewelry or a wrist watch, the child lies on a table that slides into a tunnel-like tube. Radio waves are directed at the body, triggering the body's atoms to create radio waves that are picked up by the MRI scanner at thousands of places around the body. The information is then used to create a composite "slice" that can be shown on a monitor and printed for further study. The process is painless but can be anxiety-producing due to the child's confinement during the procedure. Sedatives may be given if the child is unable to hold still or is especially nervous. It is very noisy inside the chamber, and ear plugs are usually given to help dampen the noise. Earphones are also available for children who would like to listen to tapes. The scan takes 30 to 60 minutes.

"Open MRI" scanners are available at some hospitals. These scanners do not involve a confining "tunnel" and are faster and less noisy, making them more ideal for children.

How long will it take to get results?
MRI results are interpreted by a radiologist and sent to your doctor, who will present them to you, usually in a day's time.

Radioisotope (Nuclear) Scan
A number of tests use very small quantities of radioactive materials, called radioisotopes, to image parts of the body. The radioisotope is attached to another substance that is injected, inhaled, or swallowed. Special devices then sense the positioning of the radioisotopes and make an image of them as they appear in your child's internal organs. It's almost like the reverse of an X-ray - instead of being directed onto the body, the radiation comes from inside it. Swallowing radioactive substances sounds dangerous, but the quantity and duration of radioactivity in these tests have been designed to be maximally safe for humans and should not have any harmful effects whatsoever.

Urinary Bladder Scan
This study is called a radionuclide voiding cystogram. It is used to detect reflux (back-flow) from the bladder to the kidney(s), which is abnormal and is associated with infection.

How is the scan done?
A small amount of radioisotope is added to a fluid, and the fluid is introduced into the bladder by a catheter. The bladder is filled, and then the patient voids. Images are obtained throughout the test to detect reflux.

How long will it take to get results?
The results will be reported to your doctor, who will present them to you.

Ultrasound (Sonography)
Ultrasound can examine many parts of your child's body. It uses high-frequency sound waves to "echo" off the body and create a picture of it. Some of the organs frequently examined by ultrasound are: the kidneys, the liver and spleen, the brain, the female pelvis, and the hips.

How is an ultrasound done?
A special jelly is applied to the skin on the area that is being investigated, and a wand (the transducer) is positioned over it.Sound waves are generated and reflected back to the transducer, and the image becomes visible on a monitor. Printouts are then made from the screen. The procedure is painless.

How long will it take to get results?
The images are created immediately, but they must be interpreted by a radiologist. Results will be reported to your physician, who will interpret them for you.

X-Ray (Radiography)
The first of the body imaging tests, X-rays were discovered by Wilhelm Roentgen in 1895. They consist of electromagnetic radiation, like light, but have a shorter wavelength. They penetrate the body and form an image on film. 

Any part of the body can be X-rayed for information, and they are particularly useful in looking at injuries or changes in bones. Chest X-rays are commonly done as part of routine physicals in adults, and are useful in detecting the presence of pneumonia or other lung diseases and determining heart size.

Some tests use dyes or other materials (such as barium) that show up on X-rays to outline structures within the body. An "upper GI," for example, involves having the patient swallow one of these contrast materials, then taking X-rays to examine the progress of the material through the stomach and upper small intestine. The contrast material will give the radiologist an "inside look" at the shape of the gastrointestinal tract. 

A myelogram is an X-ray test of the spine; dye is injected into the spinal fluid to outline the spinal cord. An arthrogram is an X-ray of a joint, usually the knee or hip. A dye is injected into the joint to make the picture clearer and to enable detection of a tear in the cartilage or other joint abnormalities.

In fluoroscopy, a moving picture of the body is seen as the test is performed and is recorded on videotape or as still images. This technique can be used to evaluate the gastrointestinal tract, the respiratory system, and the bladder, among other things. Fluoroscopy and other specialized tests are performed by a radiologist with the assistance of a technologist.

An intravenous pyelogram (IVP) is a test that uses a contrast dye to outline the kidneys, ureters (the tubes that carry urine from the kidney to the bladder), and bladder on an X-ray. The dye, which is given through a vein, helps the radiologist evaluate kidney function as well determine any abnormalities in the structure of the urinary system.

How is an X-ray done?
The child is positioned so that the X-ray machine can take a picture of the area being investigated. The procedure is painless. The test is usually performed by a technologist in the radiology department of the hospital, and results are interpreted by a radiologist.

How long will it take to get results?
The images are available in minutes, but they must be interpreted by a radiologist. Results will be sent to your doctor, who will present them to you.

Updated and reviewed by: Kim Rutherford, MD
Date reviewed: September 2001
Originally reviewed by: Neil Izenberg, MD, and Frederick Meier,