What is CT – Spine?

A type of x-ray examination that uses a CT scanner to obtain multiple images of the spinal column, that can be changed by the computer after they have been acquired into three-dimensional images if needed. These detailed images may be examined on a computer or printed out like x-rays.

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What are some common uses of CT of the Spine?

• Detect (or rule out) spinal damage in patients with injuries.
• Evaluate the spine before and after surgery.
• Detect various types of tumour in the vertebral column.
• Examine a narrowing spinal canal, a vertebral fracture, an infection, or degenerative disease such as arthritis.
• Find if spinal pain is related to a herniated intervertebral disk.
• Detect risks of osteoporosis.
• Guide procedures like a biopsy or abscess removal.

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How should I prepare for the procedure?

• Clothing: wear comfortable, loose-fitting clothing on your way to the imaging center. There, you will be given a hospital gown to put on. Any metal object must be removed before exam (jewellery, eyeglasses, dentures, hairpins, etc.).
• Fast: you may be asked not to eat or drink anything for several hours beforehand, especially if you are to receive contrast material which may be a drink be given an injection which in some cases is required to improve the image .
• Allergies: tell the physician or technologist if you have allergic reactions, especially to iodine which is often present in contrast material. Any history of heart disease, asthma, diabetes or thyroid problems also.
• Anxiety: if your infant or young child is to have spinal CT, there are measures that can be taken to ensure that the test will go smoothly and will not be a cause of anxiety for either the child or parent.
• Pregnancy: a woman of reproductive age should inform her physician or the technologist if there is any possibility that she is pregnant.

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What does the equipment look like?

The CT scanner is a large unit with a hole, or tunnel, running directly through its center. The technologists helps the patient to lies on a table that can be moved up or down and that slides into and out of the center of the tunnel. The technologist then goes to an adjoining room watching through a window and/or by video camera throughout the procedure. An intercom system allows communication with the technologist.

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How does the procedure work?

In CT scanning, a source of x-rays and a set of electronic x-ray detectors rotate around the patient. The detectors absorb the x-rays that have passed through the patient and measure the amount of radiation. The information collected by the detectors is sent to a computer system that processes it and reconstructs two-dimensional cross-sectional images (the "slices") of the body part. A single slice is recorded in only a few seconds. Modern spiral CT units produce high-quality images in a short time, for example the spinal column in just minutes.

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How is the CT scan performed?

CT scanning is carried out with the patient lying on his or her back. The technologist will make sure that you are properly positioned, and may use pillows to help you maintain a correct posture during the study. If indicated, a contrast material will be injected into an arm vein during the procedure so as to sharpen the images of various tissues. A scan of the lower spine may also be done after injecting contrast material into the spinal canal surrounding the spinal cord during a lumbar puncture. This will help to detect tumors or locate areas of inflammation or nerve compression. Initially the table will move rapidly through the scanner to determine the correct starting position. Further scans then are made as the table moves more slowly through the tunnel in the scanner.

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What will I experience during the procedure?

CT scanning is painless, apart from a needle stick if an intravenous injection is needed. Discomfort comes mainly from having to lie still on the table for some time. Injection of contrast material may cause a slight burning feeling in the arm, a metallic taste, and warm flushing of the entire body. These all are normal reactions and usually end within a few seconds. Patients who have a hard time remaining still or who are claustrophobic may find CT to be stressful. The same may be the case for those who have chronic pain. If you are one of these patients, the technologist may give you a mild sedative to help get you through the exam.

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What happens with the results?

A radiologist will review the findings and make a detailed report to your primary care physician. Your doctor's office will let you know when the results are in and how to obtain them. Having had a spinal CT study, you and your doctor will be better able to decide on further diagnostic procedures or treatment.

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What are the benefits vs. risks?

Compared to regular x-rays, CT scanning uses a relatively low dose of radiation. Although non-invasive, the examination sometimes require a contrast material injected into a vein before scanning, in order to show fine details and highlight any abnormalities.

Benefits

• Rapid procedure with an accurate evaluation.
• Non-invasive and painless.
• CT is less expensive, and more cost-effective, than MRI. In addition, it is less sensitive to patient movement. Unlike MRI, CT may be carried out in patients who have an implanted device of any kind.

Risks

• Exposure to radiation, with doses lower than those used in some general x-ray exams but higher than in others. Damaging effects of radiation may be more of a risk when multiple CT studies are carried out over a period of time.
• possible risk to the fetus: pregnant women should consult their physician first. Children should have a CT study only if it is essential for making a diagnosis. In general, the benefits of CT scanning outweigh the potential harm from radiation.
• Allergic reaction to iodine (contained in contrast material) such as itching, hives, nausea, or rapid breathing, which is easily treated. Severe reactions including difficulty breathing are quite rare but do occur. Kidney failure is another very rare occurrence; it is likeliest to develop in patients whose kidney function already is impaired.
• Nursing mothers should avoid breast-feeding their infants for 24 hours after receiving an injection of contrast medium.

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What are the limitations of CT Scanning of the Spine?

• Spinal CT does not consistently show enough detail to properly assess the spinal cord. MRI is also more suitable than CT for demonstrating injured ligaments, the status of the intervertebral disks, and hematomas in the area of the spine.
• CT scanning fails to identify some vertebral fractures that are not displaced.
• Contrast material must sometimes be injected to obtain clear images of blood vessels, tumor tissue, muscle and fluid.
• CT scanning is, in general, not recommended for pregnant women. Young children should not have repeated CT studies unless absolutely necessary.
  

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