What is Pediatric CT?Computed tomography, also known as CT or CAT scan, is a type of x-ray imaging procedure which, like conventional x-ray imaging, is based on varying absorption of x-rays by different body tissues. In a CT exam, the beam of x-rays moves in a circle around the body, providing different views of the same organ or tissue in much greater detail than a conventional x-ray exam. A computer processes the imaging information and displays it on a monitor. In children as well as adults, CT scanning may be preferred to the customary x-ray exam. It may be performed in newborns and infants as well as older children and adolescents. CT scans may be done with or without contrast materials that are taken by mouth or injected into a vein. These contrast-enhanced exams often depict a particular organ, tissue, or blood vessel more clearly. |
|
What are some common uses of the procedure?A CT scan may be recommended in order to detect a wide range of abnormalities or diseases in any part of your child's body. Among the more common reasons for requesting a CT scan are infectious or inflammatory disorders, abdominal pain, headaches, and injury-related changes. CT also may be used to demonstrate birth defects, detect cancer, and to periodically check to see if previously treated disease has recurred. CT can evaluate the blood vessels serving the brain, face or neck. In children suffering head injuries the exam can display or rule out serious complications such as bleeding within the brain or other forms of brain damage. In addition, CT can display the spinal cord and the bones making up the spinal column. Except for the chest x-ray, CT is the most commonly used imaging procedure for evaluating the chest. Some of the more common conditions that may be imaged by chest CT are:
CT can demonstrate injured blood vessels or lung damage in children. Using a newer type of CT called multidetector CT it is possible to obtain very detailed pictures of the heart and large blood vessels of the chest in children, even newborn infants. CT is well-suited for visualizing diseases or injury of important organs in the abdomen including the liver, kidney and spleen. A common condition that may be diagnosed by CT is appendicitis. A CT scan is especially helpful in a child with appendicitis who does not have typical symptoms or who has symptoms but an inconclusive ultrasound study. CT has proved helpful for evaluating adolescents who have inflammatory disorders of the bowel such as colitis and for detecting abdominal tumors or birth defects. CT scans of the pelvic region may help to find cysts or tumors of the
ovary, abnormalities of the bladder, stones in the urinary tract, and
disease of the pelvic bones. |
|
How should my child be prepared for the CAT scan?If intravenous contrast material is to be used in the exam, the CT staff will need to know whether your child has had a reaction to contrast material in the past; is allergic to iodine or seafood; or has kidney disease. The purpose of asking about allergies is to avoid a possibly serious allergic reaction. Your child may eat and drink as usual and take needed medication as long as no contrast is to be given and no sedative (calming medication) or anesthesia is planned. If either of these situations applies, you may be advised about dietary restrictions or receive other instructions. With sedation or anesthesia your child probably will not be allowed to eat for three to six hours, depending on age, before scanning. In general, children who have recently been ill are not sedated or anesthetized. If this is the case or if you suspect that your child may be getting sick, you should call the CT staff to see whether the exam should be rescheduled. For a head or neck scan you will have to remove your child's glasses,
any removable dental braces or dentures, and any jewelry. For a scan
of any other part of the body, all metal objects should be removed from
the area being examined. |
|
What does the equipment look like?The CT scanner is a large rectangular unit with a hole in its center, resembling a gigantic doughnut. Your child will lie on a motorized table set on tracks, which can move up or down and slide into and out of the central opening. Both the tube that emits the x-ray beam and the detectors that record radiation passing through the body are built into the scanner and are not visible to the patient. The computer that processes the CT images is in a remote location. The CT staff will be in a nearby room from which they control the scanner. Your child will be in constant sight via closed-circuit television and through a window into the CT room. Speakers and microphones inside the scanner will permit the technologist to both hear and speak to your child as scanning proceeds. Some units have a call bell within reach so that you or your child can inform the technologist if any problems arise. |
|
How does the procedure work?Like conventional x-ray imaging, CT is based on the fact that different tissues, organs, and disease-related changes in the body absorb x-rays to varying degrees. Both the standard radiograph (commonly called an x-ray) and the CT image represent a picture of the radiation that has passed through the body rather than being absorbed. What is different about CT scanning is that the images are cross-sectional "slices" of the area of the body suspected of being abnormal. The radiation passing through the body is recorded by a set of detectors that rotate within the scanner and around the body. The resulting image data are processed using a special computer program that combines individual x-ray paths into detailed slices of the part of the body being examined. Your child may receive contrast
material by mouth, by rectum, by injection into a vein, or by multiple
methods so that the organ or tissue being examined will be seen more
clearly. Using contrast material also makes it easier to detect certain
abnormalities affecting blood vessels. |
|
How is the CAT scan performed?After receiving oral or intravenous contrast material if needed, and a sedative if judged necessary, your child will lie down on the scanner couch and be made as comfortable as possible. The head is supported in a cushion using soft straps to maintain alignment. The exact body position depends on what area is being scanned. You should encourage your child to report any discomfort during positioning because it is important to keep very still during the exam. Once the child is correctly positioned the CT staff will leave the room to begin the scan. For the first scans the couch will move through the scanner to determine its correct starting position for the rest of the scans. The table then will move more slowly as the actual CT scan is performed. In adults, breath holding is an important way of obtaining high-quality CT images. Most children older than six years are able to hold their breath long enough to complete the scan, although they may need coaching and practice. Younger children may be able to hold their breath when asked, but are not as reliable as older children and may not be able to hold their breath long enough to complete the scan. Irregular breathing can affect the quality of a CT scan, especially one done to evaluate the chest or upper abdomen. It is often better to have young children breathe quietly and regularly during the scan. The technologist will help to decide about this. Modern systems known as multidetector or multislice CT are able to image large regions of the body in a very short time. After the study is completed you may be asked to wait for a short time
while the radiologist checks the scans to make sure they are clear enough
to be easily interpreted. Occasionally it is necessary to have a few
scans repeated. |
|
What will my child experience during the procedure?Modern CT imaging avoids the start and stop noises made by the earlier scanners. This tended to disturb children more than the gentle, continuous movements of the scanner and table during more quiet spiral CT scanning. With modern imaging there are only slight buzzing, clicking or whirring sounds. Your child will need to lie quietly on his or her back. Foam cushions and Velcro straps are placed on the forehead and arms to prevent movement. A CT scan may take as little as two seconds or as long as several minutes, depending on the information needed. However, preparing for the study will take longer. Some imaging facilities permit parents or other adults to stay in the room when the scan is performed. In this case, you must wear a lead-lined garment to avoid exposure to radiation. If you suspect you may be pregnant it would be better for someone else to be with your child. Many children are put off or even frightened by large machines and the general atmosphere of a medical facility; the presence of a parent, close relative, or friend can be very reassuring. If contrast material is injected into a vein, your child will feel warm all over, but only for a brief time. There will likely be minor pain when the needle is placed into the vein; it is like getting a shot. When the exam is completed and your childif sedatedis fully awake, you will be free to return home. Some imaging facilities may use general anesthesia
in young children who are unable to hold still. In this case you will
be permitted to stay until your child has fallen asleep. There may be
a somewhat longer wait after the exam to be sure that your child is
fully alert. |
|
Who interprets the results and how do we get them?The CT images will be printed out from the computer or sent to a monitor and examined by a radiologist. The results should be available within 24 hours. The physician who recommended your child's exam will receive a detailed report by fax, mail or electronically, and will in turn pass on the information to you. CT technologists are not trained to interpret the findings, and it is not their responsibility to do so. |
|
What are the benefits vs. risks?Benefits
Risks
|
|
What are the limitations of Pediatric CT?
To locate a medical imaging or radiation oncology provider in your community, you can search the ACR-accredited facilities database. This procedure is reviewed by a physician with expertise in the area presented and is further reviewed by committees from the American College of Radiology (ACR) and the Radiological Society of North America (RSNA), comprising physicians with expertise in several radiologic areas. |
|
|
|
|
This page was reviewed on: June 02, 2003 |