Cat Scan, Head Cranial Ct Scan

Computed tomography, also called CT, of the brain is anoninvasive imaging method that combines X-rays with computertechnology. X-ray beams from several angles are used to create aseries of detailed cross-sectional images of the brain.

Who is a candidate for the test?

CT is an excellent method for viewingthe structures of the brain. It can provide detailed images of severaltypes of tissue including bone, soft tissue, and blood vessels. Forthis reason, it can be used to:

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diagnose brain tumors

gather data on head injuries

guide radiation therapytreatments

A cranial CT scan can help a doctor diagnose and treat the followingconditions:

brain tumorsand 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 disease

ruptured or leaking 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 medicines

is allergic to shellfish or to foods with added iodine such as table salt

has ever had claustrophobia, which is a fear of enclosed or small spaces.If this is a problem, mild sedating medicine may be given.

A woman will be asked if she might bepregnant.Often, a urine pregnancy testwill be done on females of childbearing age before the CT scan.

The person having a CT scan will first need to remove itemsthat can interfere with the images, such as wigs, hairpins, clips, andremovable dental hardware. The person lies on a flat platform with hisor her head on a special pillow. This pillow provides comfort, which helpsto limit movement during the scan.

Next, the table slowly movesinto the donut-shaped machine. When the table is in the right position,the device delivers X-ray beams through the person’s brain and skull frommany angles.

Often, a special substance called a contrast agent isused to enhance internal brain structures and improve the quality of thefinal images. Typically, the contrast agent is injected into a vein in thearm. Most CT tests take between 10 and 45 minutes. Thescanning process is painless. To make sure the final images are clear,the person must lie still during the whole exam.

The contrast agent may cause mild nausea in some people.Flushing, itching, and a metallic taste in the mouth are often described inpatients who receive an injected contrast agent. Most of these feelingsgo away within a few minutes.

After the test, the person will be asked to wait until thepictures are looked at to see if any more are needed. The personwill be observed for any delayed reactions to the contrast agent.To help rid the body of the contrast agent, he or she may be asked todrink extra fluids.

What is involved in preparation for the test?

The person having a CT should not eat ordrink for at least 4 hours before the test. The CT technologist willexplain how the test is done. People who are prone to claustrophobia willreceive a calming medicine before the exam.

What do the test results mean?

A doctor specially trained in analyzing CT images,called a radiologist, will examine the results of the test. He or shewill forward a report of the findings to the person’s doctor.

A cranial CT can reveal:

brain tumors

cerebral aneurysms

abnormalities in the structures of the brain

stroke from cardiogenic embolism,or a blood clot that has traveled to the brain

abscesses

intracerebral hemorrhage,or bleeding in the brain

multiple sclerosis