The development of techniques for viewing internal organs served as the bedrock on which many of the landmark developments in modern medicine was built. A CT scan is one of these landmark viewing techniques. CT is an abbreviation for Computed Tomography and it basically is a specialized form of X-ray. The scan is capable of highlighting specific areas of the body that may be beyond the view of ordinary X-rays. CT scans can view organs, bones, tissues and blood vessels in the body.
Advantages of CT scans
- CT scans are fast and easy to carry out
- They are usually painless and non-invasive
- It is ideal for claustrophobic patients
- A contrast material can highlight important, hard to see areas.
CT scans with contrast
Often, an ordinary CT scan may be insufficient to view certain body parts with the desired amount of clarity. In these situations, CT scans with contrast may be a good choice. Contrast media serve to highlight the body part of interest. This gives your doctor the ability to better examine your body for diseases. The procedures for a CT scan with contrast slightly differs from an ordinary CT scan. The contrast material is first introduced into your body before the scan. Under normal circumstances, the material should be non-drowsy and non-toxic.
What can they detect
As highlighted earlier, a CT scan with contrast is a valuable diagnostic tool. It provides an easy and accurate method of examining the chest, pelvis, and abdomen. It has also proven very useful in the diagnosis of different types of cancers. Lymphoma, cancers of the kidney, lung, pancreas, liver and many other organs can all show up in CT scans. Apart from revealing the tumor, the scan shows the exact location and size and also reveals some information about metastasis.
CT scans with contrast have proven invaluable in the diagnosis of diseases that affect small vessels. Embolisms and aneurysms can be clearly assessed and complications such as strokes and heart attacks can be prevented. The extent and location of bone and muscle injuries are also better appreciated using CT scans. In emergency situations, CT scans detect internal bleeding and the affected vessel can be repaired in time to save the victim’s life.
Routes of administration of Contrast
There are three ways that your doctor might administer contrast fluid:
Contrast solutions administered orally are usually safe and end up digested like normal food. You should inform your doctor if you have any allergies or medical conditions before taking oral contrast solution.
Oral contrast solutions consist of either Barium or Gastrografin. Both substances possess an attenuating effect on X-rays. As the CT-Xray beam passes through the part of your GIT containing the contrast material, the attenuated beam makes the part in question clearer. Depending on your physician’s advice, you should not eat or drink anything a few hours to the scan.
The rectal route is for when the large intestine or other organs in the pelvic region is the subject of the scan. They are administered in the form of an enema with the patient lying down. With the rectal administration of contrast substances, organs such as the bladder and uterus are also made more visible on the CT scan with contrast. Generally, the same safety guidelines are applicable for the rectal and oral administration of Barium and Gastrografin as contrast materials.
The Intravenous administration of contrasts is particularly useful when the intention is to highlight blood vessels or internal organs such as the kidneys, the brain, spinal cord etc. Sometimes, intravenous administration may be combined with the oral or rectal route to increase sensitivity. The contrast material is injected into a vein, usually on the hand or arm via a power-assisted injector. The injector runs for a specified amount of time during the CT scan with contrast. Iodine is the contrast material administered intravenously during CT exams.
Reactions to iodine are more common as compared to Barium or Gastrografin. This does not mean iodine is dangerous for you. The benefits of using iodine clearly outweigh the risk, and you can trust your doctor to make the best decisions. Before you carry out the procedure, inform your doctor about any history of allergies, breathing problems and thyroid problems. Your physician should also be aware of any heart or kidney conditions.
The common side effect of intravenous iodine is a metallic taste in the mouth or hot flush. This is usually self-limiting and lasts for a few minutes. It does not require any treatment. Less commonly, you may experience generalized itching with hives. You may need to take an antihistamine for this.
Rarely, severe allergic reactions may occur and you may experience difficulty in breathing or swelling of the throat. Your radiographers and radiologists are well aware of these risks. They would have put in place measures to take care of any occurrence.
Who is not eligible
The majority of people can undergo CT scans safely. The major drawback used to be the potential for allergic reaction to iodine. This has been greatly reduced with the development of non-ionic contrast. The contrast solution used in this method contains modified iodine. There has been much less occurrence of allergic reactions to non-ionic contrasts. Ensure you provide your caregivers with a full medical history to enable them to make informed decisions.
Pregnant women are usually advised to go for procedures that do not involve radiation such as MRI. This is not to say that a CT scan would harm an unborn baby. There is, in fact, no conclusive evidence showing a CT scan with contrast is dangerous to a fetus. If your doctor feels the benefits outweigh the potential risks, he may sanction the scan.
What to do before a CT scan with Contrast
You do not need elaborate preparation before going for a CT scan. Depending on the nature of the scan, you may not be able to eat or drink anything for some hours before the procedure. It is important to follow the instructions provided by the diagnostic center. Keep your jewelry at home and put on loose-fitting clothes. The center may provide an overall for you to change into before going under the machine. Finally, remember to inform your doctor of any known allergies.