Is a Cranial CT Scan?
A cranial CT scan of the head is a diagnostic tool used to
create detailed pictures of the skull, brain, paranasal sinuses, ventricles,
and eye sockets. CT stands for “computed tomography,” but is known by a variety
of names, including brain scan, head scan, skull scan, sinus scan, and CAT
A cranial CT scan is noninvasive and is usually suggested to
investigate various neurological symptoms before turning to more invasive and
a Cranial CT Scan Is Used
The pictures created by a cranial CT scan are far more
detailed than regular X-rays. They can help diagnose a range of conditions,
- birth defects
- fluid buildup
- bone abnormalities
Your doctor may order a cranial CT scan if you have had an injury
or display any of these symptoms with no apparent cause:
- seizures (especially recent onset)
- sudden behavioral changes or changes in thinking
- hearing loss
- vision loss
- muscle weakness or numbness and tingling
- speech difficulty
- difficulty swallowing
A cranial CT scan can also be used to guide other procedures
such as surgery or biopsy.
Happens During a Cranial CT Scan?
A cranial CT scanner takes a series of X-rays. A computer
then puts these X-ray images together to create detailed pictures of the head.
These images help your doctor make a diagnosis.
The procedure is usually done in a hospital or outpatient imaging
center. It should take only about 15 minutes to complete your scan.
On the day of the procedure, you must remove jewelry and
other metal objects. They can damage the scanner and interfere with the X-rays.
You’ll probably be asked to change into a hospital gown.
You’ll lie on a narrow table either face up or face down, depending on the
reasons for your CT scan. It’s very important that you remain completely
still during the exam. Even a little movement can blur the images.
Your doctor may suggest a sedative to keep your body still.
Some people find the CT scanner stressful or claustrophobic. Your doctor may
also suggest a sedative to keep you calm during the procedure.
The table will slowly slide so that your head is inside the
scanner. You may be asked to hold your breath for a short period. The scanner’s
X-ray beam will rotate around your head, creating a series of images of your
head from different angles. The individual images are called “slices.” Stacking
the slices together can create three-dimensional images.
Images can be seen immediately on a monitor. They will be
stored for later viewing and printed. For your security, the CT scanner has a
microphone and speakers for two-way communication with the scanner operator.
Cranial CT Scan for Children
Your child’s doctor may recommend a sedative to help them
remain calm and keep still.
Dye and Cranial CT Scans
Contrast dye helps highlight some areas better on the
images. For example, it can highlight and emphasize blood vessels, intestines,
and other areas. The dye is given through an IV in your arm or hand.
Often, images are first taken first without contrast, then
again with contrast. However, use of contrast dye isn’t always necessary. It
depends on what your doctor is looking for.
Your doctor may direct you not to eat or drink for several
hours before the test if you’re going to receive contrast dye. This depends on your
particular medical condition. Ask your doctor for specific instructions for
your CT scan.
and Precautions to Consider
The scanner table is very narrow. Ask if there is a weight
limit for the CT scanner table if you weigh more than 300 pounds. Be sure to
tell your doctor if you’re pregnant. X-rays of any kind are not recommended for
There are some extra precautions to be aware of if contrast
dye will be used. For example, special measures must be taken for people on the
diabetes medicine metformin (Glucophage). Be sure to let your doctor know if
you take this drug. Also tell your doctor if you’ve ever suffered an adverse
reaction to contrast dye.
There Any Side Effects or Risks?
The CT scan itself is a painless procedure. Some people feel
uncomfortable on the hard table or have difficulty remaining still.
You may feel a slight burning when the contrast dye enters
your vein. Some people experience a metal taste in their mouths and a warm
sensation throughout their bodies. These reactions are normal and generally
last less than a minute.
CT scans expose you to some radiation. Doctors generally
agree that the risks are low compared to the potential risk of not being
diagnosed with a dangerous health problem. The risk from a single scan is
small, but the risk increases if you have many X-rays or CT scans over time.
Newer scanners may expose you to less radiation than older models.
Tell your doctor if
you’re pregnant. Your doctor may be able to avoid exposing your
baby to radiation by using other tests. These may include a magnetic resonance
imaging (MRI) or ultrasound, which does not use radiation.
Discuss the risk of cranial CT scan with your doctor before
the test so you can assess the potential risks and benefits for your medical
Allergic Reaction to Contrast
Tell your doctor before the scan if you’ve ever had an
allergic reaction to contrast dye.
The contrast dye commonly contains iodine and may cause
nausea, vomiting, rash, hives, itching, or sneezing in people who are allergic
to iodine. You may be given steroids or antihistamines to help with these
symptoms before you receive the dye injection. You may need to drink extra
fluids after the test to help flush the iodine from the body if you have
diabetes or kidney disease.
In very rare cases, contrast dye can cause anaphylaxis, a
whole-body allergic reaction that can be life-threatening. Notify the scanner operator immediately if
you have trouble breathing.
the Results of Your Cranial CT Scan
A radiologist will interpret the results and send a report
to your doctor. The scans are stored electronically for future reference. Your
doctor will discuss the radiologist’s report with you.
Some conditions that can be identified through cranial CT
- brain aneurysm
- bleeding in the brain, or hemorrhage
- brain tumor or other mass
- brain infection (e.g., abscess) or swelling
- abnormal blood vessels (arteriovenous
- atrophy of brain tissue
- fluid buildup in the skull (hydrocephalus)
- fracture or injury to head, face, or skull
- abnormalities of the bone of the skull
You should be able to return to your normal routine after
the test. Your doctor may give you special instructions if contrast was used in
Your doctor will go over your results with you once they’re
ready. Depending on the results, your doctor might order more tests.