Ultrafast/Electron Beam CT Scan

What is an ultrafast/electron beam CT (computed tomography) scan?

In standard X-rays, a beam of energy is aimed at the body part being studied. A plate behind the body part captures the variations of the energy beam after it passes through skin, bone, muscle, and other tissue. While much information can be obtained from a regular X-ray, specific detail about internal organs and other structures is not available.

With computed tomography (also called CT or CAT scan), the X-ray beam moves in a circle around the body. This allows many different views of the same organ or structure, and provides much greater detail. The X-ray information is sent to a computer which interprets the X-ray data and displays it in 2-dimensional form on a monitor.

A technology called ultrafast CT (also known as electron-beam tomography, or EBT) is used, in some cases, to diagnose heart disease. Ultrafast CT can take multiple images of the heart within the time of a single heartbeat. This provides more detail about the heart's function and structures, and also greatly decreasing the amount of time required for a study.

• A 3-dimensional (3D) version of ultrafast CT may be used to assess the pulmonary arteries and veins in the lungs.

• Ultrafast CT scan may also be used to evaluate selected heart defects after birth, as well as other structures in or near the heart.

Risks and possible complications of CT

Risks and possible complications include: 

• Radiation exposure from X-rays (only with CT)

• Problems with undetected metal implants or foreign bodies (only with MRI)

• Reaction, like headaches, shivering, and vomiting, to sedative or anesthesia

• Allergic reaction, like hives, itching, or wheezing, to contrast dye

• Rarely, kidney damage from IV contrast dye used in CT

• Extremely rarely, an illness called nephrogenic systemic fibrosis has been linked to MRI IV contrast material

What is the preparation for an ultrafast CT scan?

An ultrafast CT scan can be performed with or without contrast dye. If your child's health care provider schedules an ultrafast CT scan of the heart or chest and decides to use contrast dye, your child may need to be NPO (fasting, nothing by mouth) for several hours before the procedure. You will receive instructions about this from your child's health care provider or another health care professional.

You will need to let your child's health care provider know if your child has ever had a reaction to any contrast dye, or if he or she is allergic to iodine. The risk of a serious allergic reaction to contrast materials containing iodine is rare, and radiology departments are equipped to handle them. A reported seafood allergy is not considered to be a contraindication for iodinated contrast. If your teenage daughter is pregnant or could be pregnant, you should notify the health care provider before the procedure.

How to help your child prepare

You can help your child by preparing him or her in advance. How you do this depends on your child’s needs:

• Explain the test to your child in brief and simple terms. Younger children have shorter attention spans, so do this shortly before the test. Older children can be given more time to understand the test in advance.

• Make sure your child understands which body part(s) will be involved in the test.

• As best you can, describe how the test will feel. An IV may be inserted into the arm or hand to give medicines or contrast dye. This may cause a brief sting. Your child won’t feel any discomfort once the medicines take effect. If awake, your child may become uncomfortable from lying still.

• Allow your child to ask questions and answer these questions truthfully. Your child may feel nervous or afraid. He or she may even cry. Let your child know that you’ll be nearby during the test.

• Many hospitals have a child life specialist. This person is specially trained to help children understand what to expect during their time in the hospital. Books, videos, dolls, and toys may be used to help explain the procedure to your child. Be sure to ask your child’s health care provider about the resources available at your hospital.

How is the ultrafast CT scan performed?

The ultrafast CT scanner is located in a large room. Your child will lie on a narrow table that slides into the hollow tube-shaped scanner.

Your child will have an intravenous (IV) line if contrast medicine is being used. The contrast medicine may be injected prior to the procedure or during the procedure.

The CT technologist will be in an adjacent room where the equipment controls are located. However, they will be able to see your child through a large window and will be monitoring him or her constantly during the procedure. If your child is not sedated, he or she will be given a call bell device to let the staff know if he or she needs anything during the procedure. Speakers are located inside the scanner so that your child can hear instructions from the CT staff and they can hear your child respond. You may or may not be able to stay with your child during the procedure.

Once the procedure begins, your child will need to be remain very still at all times. Movement will not adversely affect the quality of the images. At certain times, he or she will be instructed to hold his or her breath, if possible, for a few seconds. He or she will then be told when to breathe. Your child should not have to hold his or her breath for longer than a few seconds, so this should not be uncomfortable. Young children who cannot hold still for the procedure may be given medicine to help them relax or sleep during the ultrafast CT scan.

If the ultrafast CT scan is being done "with and without contrast," your child will receive contrast medicine through an IV about halfway through the procedure. He or she may feel a warm or flushed sensation just after the dye goes into the vein. This is normal and the sensation will go away shortly.

Once the procedure is finished, the table will slide out of the scanner. If your child received medicine for relaxation or sleep, he or she will be monitored until the medicine wears off and he or she is awake again. If an IV was inserted, it will be taken out after the procedure is over and your child is awake.

You may be asked to wait for a short time while the radiologist reviews the scans to make sure they are clear and complete.

What happens after the procedure?

Without sedation, your child should be able to resume normal activities right away, unless your child's health care provider instructs you otherwise.

With sedation, your child may feel groggy, tired, or sleepy for a period of several hours after the procedure. However, the sedation effects should disappear within a day.

Depending on the results of the ultrafast CT scan, additional tests or procedures may be scheduled to gather more diagnostic information.