Medical Imaging: CT and CAT - Services

If you are having a CT scan of the head, please avoid wearing earrings, necklaces or metal hair accessories such as hair pins, barrettes, or clips.

A CT scan of your head will create highly-detailed images of your head, including the brain and bones of the skull.  It can also provide limited information about the eyes (orbits), facial bones and your sinuses. If your face is an area are of concern for your care, additional CT scanning of the face will be necessary.

Why it is done

A CT scan of the head is done to:

• evaluate symptoms such as confusion, paralysis, numbness, vision problems, vertigo, or headaches that might indicate a brain injury, brain tumor, ruptured aneurysm, or bleeding within the skull
• determine the extent of damage caused by a stroke and to help determine effectiveness of treatment for a stroke
• help determine the cause of a loss of consciousness or a decreasing level of consciousness
• detect blood clots, tumors, bleeding, infection, or increased pressure in the skull or brain
• evaluate the effectiveness of treatment for a brain tumor

CT scans of the eyes, facial area, and sinuses may be done to:

• investigate problems with your eyes and optic nerve  
• detect fractures of the bones around your eyes or foreign objects in your eye
• investigate problems of your middle ear bones and auditory nerve
• evaluate problems or diseases of your sinuses
• evaluate problems with the bones and joints of the jaw, face, and skull

An injection of “dye” or “contrast” (contrast material that contains iodine) is often required during a CT scan of the body, particularly for images of the chest, abdomen and pelvis. This dye is used to evaluate blood flow, detect some types of tumors, and locate areas of inflammation as it makes blood vessels and certain structures or organs inside the body more visible on the CT scan images.

If you are having an abdominal CT scan, you will likely be asked to take an additional dose of contrast material by mouth (orally).

Why it is done

A CT scan of the body can consist of many areas of the body, including:

• Chest (thorax): A CT scan of the chest can detect infection, lung cancer, pulmonary embolism, or a bulge in a blood vessel (aneurysm). It can also be used to help determine whether cancer has spread (metastasized) into the chest from other locations in the body.
• Abdomen: A CT scan of the abdomen can help detect several conditions, including cysts, abscesses, infection, tumors, an aneurysm, enlarged lymph nodes, foreign objects, bleeding into the abdominal cavity, diverticulitis, inflammatory bowel disease, and appendicitis. It can also help determine whether cancer has spread from another place in the body to abdominal organs or lymph nodes.
• Urinary tract: A CT scan can detect kidney stones, blockage, abnormal growths, infection, structural problems, and some diseases of the urinary tract.
• Liver: A CT scan can detect liver tumors, bleeding from the liver, and some liver diseases. It can also help determine the cause of jaundice.
• Pancreas: A CT scan can detect a tumor in the pancreas or inflammation of the pancreas (pancreatitis).
• Gallbladder and bile ducts: A CT scan can be used to investigate blockage of the bile ducts. (Gallstones occasionally show up on a CT scan, but an ultrasound test is usually used to detect gallstones.
• Adrenal glands: A CT scan can detect tumors in the adrenal glands.
• Spleen: A CT scan can be used to evaluate injury to the spleen.
• Spine and spinal bones (vertebrae): A CT scan can detect tumors, injuries, deformities, narrowing of the spinal canal (spinal stenosis), and other problems of the spine. The test can also identify a ruptured (herniated) disc of the spine and help determine if thinning of the bones (osteoporosis) is severe and affecting the spine.

Your spine consists of 33 bones, most of which are separated by discs that act as cushions for the bones. The spinal cord is surrounded by the bones of the spine (vertebrae) and a sac containing cerebrospinal fluid (CSF).  A CT scan of the spine (spinal CT) is a special type of x-ray test that produces detailed pictures of the spine and vertebrae in the neck (cervical spine), upper back (thoracic spine), or lower back (lumbosacral spine).

Why it is done

A CT scan of the spine is done to:

• Examine the bones of the spine (vertebrae),
• Further evaluate problems discovered during a conventional x-ray test
• Detect problems of the spine, such as tumors, injuries (especially fractures), deformities, or narrowing of the spinal canal (spinal stenosis)
• Identify a ruptured (herniated) disc of the spine
• Help determine whether complications of osteoporosis are present
• Evaluate problems of the spine that have been present since birth (congenital)
• Monitor the success of spinal surgery or therapy

CT enterography is an examination of the small bowel using computed tomography (CT) or computerized axial tomography (CAT) scan.  This appointment will take at least 2 hours. Please make the following arrangements for your appointment:

1. As your bowel must be empty for a CT enterography exam, the following dietary restrictions are necessary for this test:

• Avoid the use of any medications that contain bismuth, such as Pepto-Bismol, for 3-4 days before your scheduled exam and the day of your exam.
• You must not eating any solid food for 4 hours before your appointment. You may drink clear fluids only.*
• If you take medication, continue to take your usual medications with a little water.

*If you are a diabetic, you do not need to stop eating 4 hours before the test.

2. You will be asked to purchase and bring a laxative called Lactulose (250 ml) with you to your appointment. The laxative will be mixed with 1 litre of water when you arrive for your appointment and you will be asked to drink it within a 1-hour time frame prior to your scan.

What will happen at my appointment?

At the beginning of your test, an IV will be inserted and you will be asked to lie on a padded CT scan table. You will receive an injection of a smooth muscle relaxant (Hyoscine Butylbromide) to temporarily slow your small bowel movements, and of contrast dye to show the blood vessels and bowel wall.

After the test, you should plan to stay near a washroom for the rest of the day as you will have taken a large amount of laxative before the test. It is normal to have some abdomen cramping due to the laxative.

The following preparation is necessary for this test:

• You must fast by not eating any solid food from midnight until the time of your test.
• You may drink clear fluids from midnight until time of your scan.
• Your family doctor or the care provider who referred you for the CT scan will give you instructions for drinking water prior to your exam: either 2 x 500ml bottles of water at home beginning one hour prior to your appointment time OR to 2-3 bottles of flavored liquid upon your arrival in the diagnostic imaging department for your scan. 
• For a pelvic CT, we may need to insert some fluid into the rectum and/or a tampon into the vagina.