A brain scan is an image of the brain that can be obtained by specific types of x-rays. When the doctor orders a brain scan, he may be looking for abnormalities such as a stroke or a brain tumor. The doctor determines who needs this type of x-ray based on the the symptoms the individual is experiencing.

There are two main types of brain scans that are used most often. The CT brain scan and the MRI brain scan. The CT scan is usually the first type of image that is ordered if an individual presents to the emergency room with symptoms of a stroke.

During a CT scan, the individual will lie on a table. The table will slide into a large circular tube. The interior of the CT scanner rotates around the individual to take pictures of the entire brain. Sometimes the doctor may order a contrast material injected into the vein to help highlight abnormal areas in the brain.

These images can be viewed by the doctor in "slices" to detect any abnormalities. The brain on a CT scan will look gray. Abnormalities will show up as darker areas or white areas in the brain or surrounding tissue. The type of stroke that an individual experiences can usually be determined by the CT brain scan.

There are two types of strokes. One type is called an ischemic stroke. This occurs when blood supply to the brain is blocked, which causes a part of the brain to die. An ischemic stroke area will appear darker than the normal brain color on the CT scan.

A hemorrhagic stroke occurs when a blood vessel in the brain ruptures and bleeding into the brain occurs. The blood in the brain will show up as a white area on the CT scan. There are times, however, when the CT scan cannot detect a stroke right away. Sometimes the area of the brain affected by the stroke will not appear abnormal for several hours.

The CT scan is the first type of x-ray performed in the emergency room. If a definite diagnosis cannot be made from the CT scan then an MRI scan is usually ordered. The MRI brain scan can take a more detailed picture of the brain. It uses magnets, along with radio waves, to transport an image of the inside of the brain to a computer screen.

When an MRI is being performed, the individual will lie on a table and the table will be slid into a long tunnel. The magnets of the MRI machine will take pictures of the brain from all angles. These pictures can provide a much clearer image of the soft tissue of the brain. The MRI brain scan produces a more detailed image of the brain. It can detect abnormalities that the CT scan could not.