Sunday, September 12, 2010

CT Scan Brain

Cranial CT Scan Brain

A CT or CAT scan (computed tomography) is a much more sensitive imaging technique than x-ray, allowing high definition not only of the bony structures, but of the soft tissues.
A CT Scan is short for computerized axial tomography of the brain. It utilizes x-rays which are combined by a computer into a single picture. This process enables the physician to obtain a series of pictures of the brain without invading the brain itself. It is used primarily to rule out organic disease such as a tumor or bleeding in the brain as a cause of the headache problem. A CT Scan can be performed with or without dye. The dye may enhance the detection of a brain tumor or a blood clot. The dye is iodine based so it must be used with caution in those with allergy to these agents. It is more sensitive than MRI scans for detecting acute bleeding on the brain. However, the MRI scan is useful for looking at other brain conditions and takes pictures at different angles than the CT. The MRI does not use x-ray or iodine dye.Clear images of organs such as the brain, muscles, joint structures, veins and arteries, as well as anomalies like tumors and hemorrhages may be obtained with or without the injection of contrasting dye.

Special CT scans are done to study the paranasal sinuses. This is useful if sinusitis is suspected. A typical series of CT scans for the sinuses use less x-ray radiation than a standard complete set of x-rays. However, a CT scan of the sinuses does not show any brain tissue. Most CT scans of the head do not .include all of the sinuses.

Alternative Names computed tomography, brain, computed tomography, head, CAT scan, brain, CAT scan, head, CT scan, brain, CT scan, head, Computerised Axial Transverse Tomography (CATT)
Definition Computed tomography of the brain is a non-invasive imaging method that combines x-rays with computer technology. X-ray beams from a variety of angles are used to create a series of detailed cross-sectional images of the brain.
Who is a candidate for the test? Computed tomography is an excellent method for viewing the structures of the brain. It can provide detailed images of several types of tissue including bone, soft-tissue and blood vessels. For this reason, it can be used to:
  • provide information on brain and central nervous system diseases such as encephalitis and general paresis from syphilis
  • diagnose brain tumours
  • gather information on head injuries
  • guide radiation therapy treatments
Some of the conditions commonly investigated with a cranial CT scan include:
  • brain tumours and other abnormal brain growths
  • skull fractures
  • brain damage after head injury
  • bleeding in the brain after a stroke
  • diseases of the inner ear such as Meniere's disease
  • ruptured or leaking brain cerebral aneurysms
How is the test performed? Before the test the doctor will ask the person if he or she:
  • has any drug allergies, or history of allergic reaction to medications
  • is allergic to shellfish, or foods with added iodine such as table salt
  • has experienced claustrophobia, or anxiety in enclosed spaces. If this is a problem, mild sedating medication may be given.
A woman will be asked if there is a possibility she might be pregnant. Frequently, a urine pregnancy test will be performed on females of child-bearing age before the CT scan.
The person having the test will first need to remove items that can interfere with the images, such as wigs, hairpins, clips and removable dental hardware. The person lies on a flat platform.
The individual's head is placed in a special pillow to allow for comfort and to limit movement during the scan. The table slowly moves into the donut-shaped machine. When the table is in the appropriate position, the device delivers x-ray beams through the person's brain and skull from a variety of angles.
Frequently a special substance called a contrast agent is used to enhance internal brain structures and improve image quality on the final images. Typically, the contrast agent is injected into a vein in the arm.A conventional CT test takes between 10 and 45 minutes. The scanning process is painless. To prevent distortion of the final images, the person must lie still for the duration of the examination.
The contrast agent may cause mild nausea in some people. Flushing, itching and a metallic taste in the mouth are frequently described in patients who receive an injected contrast agent. Most of these sensations disappear within a few minutes.
After the test, the person will be asked to wait until the pictures are examined to see if any more images are needed. The person will be observed for any delayed reactions to the contrast agent. Also, the individual will be encouraged to drink extra fluids to help rid the contrast from the body.
What is involved in preparation for the test? The person having a CT will need to refrain from eating or drinking for at least 4 hours prior to the test. The CT technologist will explain the procedure to the individual. People who are prone to claustrophobia will be given a calming medication before the examination.
What do the test results mean? A doctor specially trained in analysing CT images, called a radiologist, will examine the results of the test. The radiologist will forward a report of the findings to the individual's personal doctor.
Some of the conditions a head CT can reveal include:

    * brain tumours
    * cerebral aneurysm
    * abnormalities in the structures of the brain
    * stroke from cardiogenic embolism, or a blood clot that has traveled to the brain
    * abscess
    * intracerebral haemorrhage, or bleeding in the brain
    * multiple sclerosis


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