Computed Tomography (CAT or CT) Scan Of The Brain

What is a brain CT scan?

Computed tomography (CAT or CT scan) is a procedure that involves noninvasive diagnostic imaging using a combination of computer technology and X-rays to produce axial or horizontal images (commonly known as slices) of a patient’s body. CAT scan images are well-defined and provide detailed images of any body part, including the muscles, organs, bones, and fat. These scans are much finer and more detailed than typical X-ray images.

In normal X-rays, energy beams are aimed at the part of the body being studied. A plate placed behind the part of the body being examined then capture the energy beam variations after they have passed through the muscle, bone, skin, and any other tissue. While this information can be acquired using a standard X-ray, many internal structure and organ details are not available.

In CAT or computed tomography scans, the energy beam moves in circular motions around the body. By doing this, it becomes easier for the scan to capture different views of the same structure or organ. The information is then sent to a computer, which then interprets the data before displaying it in a dimensional form on a computer monitor.

CT/CAT scans can be performed with or without contrast – which is the substance, either injected through an IV (intravenous) line or taken by mouth, which highlights particular tissues or organs being studied to be seen more clearly. Contrast examinations could require a patient to fast for a specified period before they undergo the procedure. Your technician or physician will advise you about this before proceeding with the procedure.

Brain CT/CAT scans can provide more comprehensive information about brain structures and tissues than a standard head X-ray, therefore, providing more detailed brain injury or disease information than the standard X-ray.

Other brain scan related procedures used to diagnose disorders of the brain include brain magnetic resonance imaging or MRI scanning, cerebral arteriogram, and brain positron emission tomography or PET scanning.


When is a CT/CAT scan of the brain required?

A CT/CAT scan of the brain can be performed to evaluate the brain for injuries, structural anomalies like hydrocephalus, intracranial bleeding, tumors and other lesions, brain function and other conditions, and especially if other types of examinations like a physical examination or X-rays are inconclusive.

CAT/CT scans of the brain could also be used to evaluate the effects of brain tumor treatment and to detect any clots within the organ that could be responsible for strokes. Another use of a brain CAT scan is to provide clarity and guidance for brain tissue biopsies or surgery.

There are other reasons why doctors could recommend a CT/CAT scan of the brain.

Risks Of Brain CT/CAT scans

You may need to ask your health care provider about the amount and levels of radiation used during a CAT procedure and the related risks in relation to your particular condition. It’s a good idea to maintain a record of your radiation exposure history if you have had other types of CT or X-rays scans performed on you in the past. Some of the known radiation exposure risks are related to the total number of times a patient has undergone X-ray examinations and treatments.

If you suspect that you are pregnant or are pregnant, then it is important that you let your doctor know well in advance. Exposure to radiation during pregnancy could affect the fetus, resulting in birth defects. If it is really necessary that you have a CAT scan of the brain, then special precautionary measures will have to be employed to ensure that the least amount of radiation is exposed to the fetus.

For nursing mothers, it is advisable that they wait for at least 24 hours before resuming breastfeeding. This way, the contrast material will have exited their systems.

If a contrast material is used, there are chances you’ll probably react to the mater. Patients who are sensitive to medications or are allergic should notify their physician beforehand. Also, it is important to notify your doctor if you have any kidney problems, or have ever reacted to any contrast media before. A documented allergic reaction to seafood isn’t considered an iodinated contrast contraindication.

Patients with kidney problems or who have experienced kidney failure before should notify their physicians beforehand as the media is known to cause kidney failure. At the same time, patients on diabetes medication Glucophage (Metformin) are advised to notify they physician before having an IV contrast as it could cause a rare condition known as metabolic acidosis. If you take this drug (Metformin), you are advised to stop using it for some time during the procedure and wait for forty-eight hours after the procedure before taking it. A blood test may be required to see how well your kidney is functioning before you can start using Metformin again.

There could be other risks, but it all depends on your particular medical condition. Make sure that you discuss any concerns you have with your doctor beforehand.

Preparation for a CT scan

Patients who are yet to undergo a computed tomography angiography (CTA) scan are given a basic set of instructions when they make the appointment.


Should you be pregnant or suspect that you might be pregnant, please consult your doctor before you schedule your scan. Other options available for you will be discussed between you and your doctor.


For clothing, keep in mind that you might be asked to change into an official patient gown. If this is the case, a gown will be provided to you. In addition, a locker will be assigned to ensure that your personal belongings are secured. Be sure to remove any form of piercings and leave all your valuables and jewelry at home.

Contrast Media

Most CT scans are usually done without a contrast media. The role of a contrast media is to improve the ability of the radiologist to view the images of the internal organs of the body.


Make sure you inform the access center representatives if you have previously had any allergic reactions to contrast media, when you schedule the CT scan. Contrast IV will may not be administered to you if you have had an anaphylactic reaction in the past to any contrast media. If your allergy was mild and moderate during the previous use of contrast, then some medication will be administered prior to the chest CT scan. All of these plans will have to be discussed to you in detail in your appointment with our doctors for the exam. However, any known reactions to contrast media must be reported and discussed with your personal physician.


You can eat and drink normally and even take your prescribed medications if your doctor decided to go with a CT scan without contrast. However, if your doctor ordered a CT scan with contrast, you will be told of restrictions prior to CT scan. Only clear liquids should be taken, and you may still take your prescribed medicine prior to the scan.


If you are a diabetic, you should eat a light meal three hours prior to the exam’s scheduled time. You might be asked to pause the use of medication for 48 hours after the scan, depending on the type of medication you use. You will be given detailed information on how to go about this, following your exam.


All patients may take the various forms of prescribed medicine as usual.

Don’t forget that based on your medical condition, the doctor might request a more specific preparation, which will be availed to you in detail.

CT scan Details: Procedure

CT scans can be performed on an outpatient basis and even as part of your stay in the hospital’s premises. The procedure will vary depending on the condition as well as the preferential aspects of your physician.

You might be asked to change into the patients’ gown, and this will be offered to you. In addition, a secure locker will be assigned to you where you can keep all of your personal items. Again, be sure to remove any forms of piercings and leave any valuables such as jewelry at home.

If your procedure involves the use of contrast, an intravenous (IV) line I started in the arm or hand for injection of the media. For the orally administered contrast, you will essentially be given a specially prepared liquid contrast preparation that you need to swallow. In some cases, the contrast can be given rectally.

Next, you will lie on the scan table, which slides into the large circular opening of the CT scanning machine. For comfort and preventing movement during the procedure, pillows and straps might be used. A technologist will be in the other room where the controls for the scanner are located. Nonetheless, you will be in a constant sight of the technologist via a window. You can communicate with the technologist via the speakers located inside the scanner. You also have a call button at your comfort to let them know if you are experiencing any problems as the procedure occurs. The technologist should be in constant communication with you, as they watch you every step of the procedure.

While the scanner starts to rotate around you, x-ray beams will be passing through the body for some amount of time. There are clicking sounds, which are very normal. The rays absorbed by your body tissue can be detected by the machine, and will be transmitted to the computer. This data will be translated into an image, and the radiologist can interpret it. More importantly, be sure to remain still throughout the procedure. You may also be asked to hold your breath several times during the procedure.

Contrast media may make you feel some effects when it is injected into the (IV) line. Such effects include a salty and metallic taste in your mouth, a flushing sensation, nausea or even vomiting, and a brief headache. The effects usually last for a short amount of time. Alert the technologist should you feel any form of breathing difficulties, numbness, sweating, or heart palpitations during the procedure.

Although the CT scan is not painful, the need to lie still for the entire procedure can be uncomfortable and even cause some pain, especially if you previously had an invasive procedure such as surgery or even an injury. In this case, the technologist will use all comfort measures possible and complete the procedure as quick as possible to minimize pain or discomfort.