Computed Tomography (CT) Scans

What is CT?
Computed Tomography(CT), also known as CAT scan, uses a limited beam of x-ray to obtain image data. The data is then interpreted by a computer to show cross sectional images of the body tissues and organs. Dense tissues, such as bones, appear white in the pictures produced by a CT scan. Less dense tissues, such as brain tissue or muscles, appear in shades of gray. Air-filled spaces, such as in the bowel or lungs, appear black.

What does the CT scanner look like?
The CT scanner has a large opening in which a table moves up and slowly through. As the patient moves through the large opening, an x-ray tube rotates around the patient obtaining images, which are then sent to a computer for interpretation.

How should I come prepared for my CT?
Clothing should be free of metal in the region being scanned. For example, for scanning of the chest shirts should have no metal buttons and bras should have no metal clips or clasps. For scanning of the pelvis pants should not have zippers or metal buttons. You may also be asked to remove jewelry, hairpins, hearing aids, removable dental work, body piercings, or any other metal in the region being scanned. Correct attire is available with private changing rooms and secured lockers. You may also be asked to refrain from drinking or eating anything 1 hour or longer before your exam. Women should inform their physician or the technologist if there is a chance of pregnancy.

How long will my CT examination take?
Allowing for paperwork and patient care time the entire process will take an average of 40 minutes. In most cases the actual time to obtain the CT images can be done in 10 to 30 seconds. The quick scan time allows us to gather information without the chance of voluntary or involuntary motion, which can degrade the images.

Who interprets my CT examination and how do I get the results?
The radiologist on-site at AMI will interpret the CT exam. A radiologist is a physician who specializes in using CT and other radiologic examinations for the detection of abnormalities of the internal organs and bone structures. A signed report with the radiologist interpretation will then be available to your physician 24 hours after your exam. Your physician's office will inform you about how to obtain your results.

Contrast agents used in CT
There are two commonly used contrast media in CT. One commonly used contrast to opacify the GI tract (stomach, small bowel, colon) is barium sulfate. This is usually taken orally, but can be administered-in some cases-rectally. The volume of CT barium sulfate to be administered will depend on the degree and the extent of contrast required in the area under examination. Your physician will inform you of the amount and the time to drink your contrast when the exam is scheduled.

Another contrast medium that contains iodine is often injected into the blood intravenously (IV) during the scan. This contrast makes blood vessels and other structures or organs more visible on the CT images. It may also be used to evaluate blood flow, detect tumors, and locate areas of inflammation. Intravenous contrast material is often used to obtain images of the brain, chest, abdomen, and pelvis; an oral contrast material is commonly given for an abdominal and/or pelvis CT scan. Contrast material may be injected in to the area around the spinal cord (intrathecally) for spinal scans.

Before the administration of IV contrast the technologist will ask the patient if they have any medicine or iodine allergies. A patient who has allergies is at higher risk of allergic reaction with the administration of IV contrast. If the patient is over 65 years of age and is having a CT exam with IV contrast, we require lab test to evaluate kidney function within the last 30 days. Poor kidney function could cause potential problems in the elimination of the IV contrast from the patient's body. At the time your physician's office schedules the appointment, they will inform you if you need lab work.

Exams commonly performed in CT (Click exam type for a definition and example of the images)

  1. CT of the Musculoskeletal System
  2. CT of the Chest
  3. CT of the Abdomen
  4. CT of the Spine
  5. CT of the Neck
  6. CT of the Sinuses
  7. CT of the Head

Computed Tomography Angiography (CTA)
CT angiography or CTA is an examination to visualize blood flow in the major arteries throughout the body. An iodinated contrast is injected through a peripheral vein instead of an artery like in conventional catheter angiography. Scans are obtained in a quick and timely manner to help diagnose conditions such as aneurysms, pulmonary embolisms, and renal artery stenosis.

Exams commonly performed with CTA (Click exam type for a definition and example of the images)

  1. CTA Aorta
  2. CTA Abdomen
  3. CTA Chest
  4. CTA Head