Cranial CT Scan
Alternate Names : Computed Tomography, Brain, Computed Tomography, Head, CAT Scan, Brain, CAT Scan, Head, CT Scan, Brain, CT Scan, Head, Computerized Axial Transverse Tomography, CATT
Computed tomography, also called CT, of the brain is a
noninvasive imaging method that combines X-rays with computer
technology. X-ray beams from several angles are used to create a
series of detailed cross-sectional images of the brain.
Who is a candidate for the test?
CT 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 feedback on brain and central nervous system diseases
such as encephalitis and general paresis
diagnose brain tumors
gather data on head injuries
guide radiation therapy
A cranial CT scan can help a doctor diagnose and treat the following
and other abnormal brain growths
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 be
Often, a urine pregnancy test
will be done on females of childbearing age before the CT scan.
The person having a CT scan 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 with his
or her head on a special pillow. This pillow provides comfort, which helps
to limit movement during the scan.
Next, the table slowly moves
into 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 from
Often, a special substance called a contrast agent is
used to enhance internal brain structures and improve the quality of the
final images. Typically, the contrast agent is injected into a vein in the
arm. Most CT tests take between 10 and 45 minutes. The
scanning 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 in
patients who receive an injected contrast agent. Most of these feelings
go away within a few minutes.
After the test, the person will be asked to wait until the
pictures are looked at to see if any more are needed. The person
will 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 to
drink extra fluids.