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CT Scan of the Head

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					CT Scan of the Head
What is it?
A computed tomography (CT) scan, also called a CAT
scan, uses x-rays to take pictures of the head from
many different angles. The pictures provide a
detailed, cross-sectional view of specific areas of the
brain. CT scans are widely used and less expensive
than other scanning technologies. A CT scan shows
changes in bone better than any other imaging
method. It is also the only scanning technique that shows images of bone, blood
vessels and soft tissue at the same time. A CT scan is often used in emergency rooms
because it can be performed quickly to screen people who have had some type of
trauma, a stroke or other life-threatening condition.

Why is it performed?
CT scans are used to help diagnose many medical conditions including strokes, head
trauma, tumors, hydrocephalus, blood clots, cerebral atrophy, internal bleeding, skull
fractures, brain aneurysms, and hearing loss. CT scans are not used to diagnose
Alzheimer’s disease. They are used to confirm or rule out other causes of dementia in
people who show signs of memory loss.

How do you prepare for the procedure?
You do not need to restrict the intake of any food or fluids before the scan. When you
arrive at the testing site, a technician will escort you to a changing room and give you a
hospital gown to put on. You will be asked to remove your clothing, jewelry and any
other items that may interfere with the scan such as eyeglasses or dentures. The
technician will show you where to store them in a locker or dressing room during the
test. After changing your clothes, the technician will escort you to the examination
room. He or she may ask you some brief questions. For example, whether you have
any allergies, asthma or difficulty with breathing. The technician will ask you to sign an
informed consent form after he or she explains the test procedure. The consent form
must be signed before you start the test.

What should you expect during the procedure?

The CT scanning procedure usually lasts between ten and 45 minutes, depending on
the number of pictures that need to be taken. Relatives and friends may or may not be
allowed in the room at the time of the scan because x-rays are being used. You will be
asked to lie down on a table. A special holder may be placed around your head to keep
it still during the scan. The table will move slightly during the test. A machine will scan
and take pictures of your head. The rest of your body will remain outside the scanner. It
is very important that you remain still and quiet during this time. A contrast dye is

Developed by Martha Quinn, Michigan Alzheimer’s Disease Research Center, 2001.
sometimes used in a CT scan to highlight areas of the brain and blood vessels. In
these cases, the technician will insert a needle in your arm and start an IV to inject the
dye. You may feel a slight amount of pain when the needle is inserted. CT scans are
painless, aside from the mild discomfort of an IV injection, if used.

Are there any risks or complications associated with the scan?
There are few risks associated with CT scans. A small percentage of individuals are
allergic to iodine, which is the usual contrast dye used during CT scans. Allergic
reactions to iodine can include hives, itching, nausea, breathing difficulty or other
symptoms. While the radiation generated from x-rays is potentially harmful, many
people believe the benefit from an accurate diagnosis far outweighs the risk. The
typical radiation dose from a CT scan is roughly equivalent to the amount of natural
background radiation received over a year’s time.

What are the limitations of the test?

CT scans are not as good as MRI at showing the precise details of brain tissue damage
that is common in people with dementia. This is due to the inferior quality of the images
and obstructed views of tissue that result from overlying bone. CT scans are not the
preferred tool for diagnosing dementia because many people with dementia will have
normal CT scans, at least in the early stages of disease.

What is the cost?
CT scans are typically less expensive than MRIs and other scans. The average cost is
between $300 and $600. Most insurance companies will pay for CT scans but you
should check with your own insurance company to make sure CT scans are covered.

Test Results
A radiologist interprets the images generated from the scan. In most cases, the
radiologist will send the results, along with a written report, to your own doctor. You
should expect the results within a few days. It’s important to remember that CT scans
alone are not enough to make a diagnosis of disease. Other critical components used
in the diagnosis of disease include: psychological testing, physical examination and an
assessment of your medical and family history.




Developed by Martha Quinn, Michigan Alzheimer’s Disease Research Center, 2001.
EEG
What is it?

Electroencephalography (EEG) is used to detect and
measure electrical impulses in the brain. Unlike other brain
scanning technologies that create a “picture” of the brain,
EEG displays an up-and-down, wave-like pattern of the
brain’s activity. During the procedure, electrodes are applied to key locations on the
head. The electrodes are connected to an EEG machine that records the activity and
displays the brain-wave pattern on a computer screen. Certain diseases and injuries
can be detected by observing this pattern of brain-wave activity.

Why is it performed?

EEG is used most often to examine people with epilepsy or other seizure disorders. It’s
also used to help diagnose or rule out head injuries, brain tumors, degenerative
diseases, stroke, sleep disorders, cerebral palsy, dementia, infections and to confirm
brain death. Many people with Alzheimer’s disease have “slow waves” that can be
observed by EEG. This test can help distinguish people with Alzheimer’s disease from
individuals with severe depression, whose brain-wave pattern is normal.

How do you prepare for the procedure?
You will be asked to wash your hair the day before the test. Do not use any gel, spray,
cream or oil on your hair after washing it. The scalp must be clean and free of oil for the
test. Avoid eating or drinking any food items that contain caffeine for at least 8 hours
before the procedure. Avoid using any sedative medication before the procedure. You
may be asked to alter your normal sleep schedule the night before the test.

When you arrive at the testing site, a technician will escort you to a changing room and
give you a hospital gown to put on. You will be asked to remove your clothing, jewelry
and any other items that may interfere with the scan such as eyeglasses or dentures.
The technician will show you where to store them in a locker or dressing room during
the test. After changing your clothes, the technician will escort you to the examination
room. The technician will ask you to sign an informed consent form after he or she
explains the test procedure. The consent form must be signed before you start the test.

What should you expect during the procedure?

In most cases, the EEG test lasts between 1.0 and 1.5 hours and is painless. You will
be asked to lie down on an examining table. A technician will attach several electrodes
to your head and scalp. Specific techniques may be used to help stimulate brain-wave
activity during the test. These techniques may include waving a flashing light in front of
your eyes or instructing you to breathe deeply and rapidly for a period of time. It is
important to stay as still and relaxed as possible during the test.

Developed by Martha Quinn, Michigan Alzheimer’s Disease Research Center, 2001.
Are there any risks or complications associated with the test?
The procedure is very safe. People who have epilepsy or other seizure disorders may
experience a seizure during the exam. In many instances, this is expected and trained
health care professionals are present to monitor people being tested.

What are the limitations of the test?

EEG is less useful than imaging techniques in determining the location of injury and the
extent of damage from strokes. Also, the test is not always accurate. It is possible for a
healthy person to have an abnormal EEG test result and for a person with disease or
injury to have a normal EEG result. For this reason, many physicians use EEG in
conjunction with other types of brain scanning tests. It is important to remember that an
EEG can only detect brain activity at the time of the test. It cannot be used to determine
how the brain functioned before the test, or how it may function after the test.

What is the cost?
The average cost is about $250 or $300. Most insurance companies will pay for EEGs
but you should check your own insurance company to make sure EEG tests are
covered.

Results
A neurologist analyzes the EEG recording to look for abnormalities in the brain-wave
pattern. In most cases, the neurologist will send the results, along with a written report,
to your own doctor. You should expect the results from your own doctor’s office within a
few days. It’s important to remember that EEG results alone are not enough to make a
diagnosis of disease. Other critical components used in the diagnosis of disease
include psychological testing, physical examination and an assessment of your medical
and family history.




Developed by Martha Quinn, Michigan Alzheimer’s Disease Research Center, 2001.
MRI of the Head
What is it?
Magnetic resonance imaging (MRI) uses radio waves
and magnets to produce detailed pictures of the brain’s
structure without obstruction from overlying bone. For
this reason, MRI is particularly useful in evaluating
tumors, tissue damage and blood flow in the brain. MRI
is considered the most sophisticated type of imaging
procedure to show the structure of the brain. (Other
scans such as the SPECT or PET are used when examining the brain’s function.)

Why is it performed?
MRI is used to diagnose or rule out many different brain and neurological disorders
such as brain tumors, strokes, multiple sclerosis, aneurysms, hydrocephalus and
diseases of the pituitary gland. While MRI cannot confirm a diagnosis of Alzheimer's
disease, it can be used to detect some changes in the brain structure that are common
in people with dementia. For example, doctors can use MRIs to check for shrinkage
and atrophy in key memory centers of the brain. MRIs can also detect multi-infarcts or
small strokes that are common in people with vascular dementia and sometimes occur
in people with Alzheimer’s disease.

How do you prepare for the procedure?
You may be instructed to not eat anything for four to six hours prior to the procedure.
When you arrive at the testing site, a technician will escort you to a changing room and
give you a hospital gown to put on. You will be asked to remove your clothing, all
jewelry, hearing aides, eyeglasses, hairpins and dentures that may interfere with the
scan. Because MRI uses magnets, you will also be asked if you have a prosthetic hip,
pacemaker, or any metal plates, pins, or screws in your body.

The technician will show you where to store your things in a locker or dressing room
during the test. After changing your clothes, the technician will escort you to the
examination room. He or she may ask you some brief questions. For example,
whether you have any allergies, asthma or difficulty with breathing. The technician will
ask you to sign an informed consent form after he or she explains the test procedure.
The consent form must be signed before you start the test.

What should you expect during the procedure?

The scan usually lasts between 60 and 90 minutes, depending on the number of images
needed. You will be asked to lie down on a table that slides into a tubular scanner.
Some people may become restless or feel closed in because of the need to remain still
during the scanning process. You can ask for a sedative if you feel symptoms of severe

Developed by Martha Quinn, Michigan Alzheimer’s Disease Research Center, 2001.
claustrophobia or anxiety. Loud knocking or humming noises may be heard as the
sliding table moves in and out of the scanner to take pictures. Earplugs may be given to
reduce the noise. Newer and more ‘open’ MRI scanners are available at some
hospitals. However, the quality of pictures made by these newer scanners may not be
as good as those from the traditional tubular scanners.

Are there any risks or complications associated with the scan?
MRI uses strong magnets. It is a safe procedure for the vast majority of people. There
are no documented side effects. However, people with cardiac pacemakers cannot be
scanned and should not be in the room during the test. Individuals who have metal
objects in their body such as inner ear implants, artificial joints, artificial heart valves or
any foreign metallic object should also consult with their doctor or technician before
being scanned.

What are the limitations of the test?

There are some disadvantages of the MRI. They include the amount of time it takes to
do the scan and its sensitivity to movement. Some people feel claustrophobic while in
the scanning tube. The test is also expensive. For these and other reasons, CT scans
are preferable to MRI to assess trauma cases in emergency rooms. However, MRI is
better than CT scans in detecting diseased or damaged tissue in people with dementia.
Both types of scans are called structural scans. They show the structure or anatomy of
the brain.

While MRI is the most advanced test for scanning brain structure, other types of scans
can be used to help diagnose the cause of dementia much earlier. These include scans
that show how the brain actually works. Examples of functional scans include SPECT
and PET. Structural scans are less helpful in diagnosing dementia than scans that
show function. This is because many older adults have a certain amount of brain
deterioration, regardless of whether or not they have dementia.

What is the cost?
The cost of MRI varies between $860 and $1,200. MRI is more expensive than x-rays
or CT scans. Most insurance companies will pay for MRI scans but you should check
with your own insurance company to make sure MRI tests are covered.

Test Results

A radiologist interprets the images generated from the scan. In most cases, the
radiologist will send the results, along with a written report, to your own doctor. You
should expect the results within a few days. It’s important to remember that MRI alone
is not enough to make a diagnosis of disease. Other critical components used in the
diagnosis of disease include psychological testing, physical examination and an
assessment of your medical and family history.


Developed by Martha Quinn, Michigan Alzheimer’s Disease Research Center, 2001.
PET Brain Scan
What is it?

Positron emission tomography (PET) is a new and
advanced scanning technique that shows how the
brain functions. More traditional tests like MRIs and
CT scans show the brain’s anatomy or structure.
PET scans produce brightly colored “maps” of the
brain’s activity. Different patterns of activity shown on *The Clinical PET by Bares & Lucignani 1996
these “maps” correspond with different diseases. PET and other new functional brain
scanning technologies allow physicians to detect the presence of disease long before
any structural damage is done to the brain. There are only three PET scanners
available in Michigan. Two are housed at the University of Michigan Hospitals. One is
located at Mott Children’s Hospital in Detroit.

Why is it performed?

PET is used to help diagnose brain disorders such as Alzheimer’s disease and other
dementing illnesses, movement disorders, brain tumors, and epilepsy. PET images
show the blood flow and metabolism of substances in the brain, such as glucose, water
and fatty acids. PET is better than other scanning techniques because it can detect
disease at the earliest stages, when the opportunity for treatment is best. This is
particularly true in Alzheimer’s disease. In general, people who have or are at risk of
developing dementia, have slower rates of metabolism and blood flow in certain areas
of the brain. PET may detect changes in brain chemistry or functioning before
symptoms appear. Researchers are starting to use PET to test the effectiveness of
various treatments for Alzheimer’s disease. They hope this kind of testing may
eventually help to find a drug that can be used in the future to either delay or prevent
the onset of symptoms. Due to its high cost and limited availability, PET is used mainly
in research studies. However, clinical use of the technology is expected to grow in the
future.

How do you prepare for the procedure?
You should check with your doctor to find out if there are any special preparations for
the PET scan. You may be asked to refrain from using alcohol, caffeine, tobacco and
all medications for twenty-four hours before the scan. When you arrive at the testing
site, a technician will escort you to a changing room and give you a hospital gown to put
on. You will be asked to remove your clothing, jewelry and any other items that may
interfere with the scan such as eyeglasses or dentures. The technician will show you
where to store them in a locker or dressing room during the test. After changing your
clothes, the technician will escort you to the examination room. He or she may ask you
some brief questions. For example, whether you have any allergies, asthma or difficulty
breathing. The technician will ask you to sign an informed consent form after he or she
explains the test procedure. The consent form must be signed before you start the test.

Developed by Martha Quinn, Michigan Alzheimer’s Disease Research Center, 2001.
What should you expect during the procedure?
Scanning times vary depending on the number of pictures that are needed. The
average scanning time is 60 minutes. You will be asked to lie down on a table that
slides into the circular opening of the scanner. The rest of your body will remain outside
the scanner while images are taken of your head. A nurse or technician will insert two
IVs in your arm. One IV will inject a radioactive tracer into the bloodstream. The other IV
will withdraw blood samples during the scan. These blood samples are checked to
determine the level of sugar and fatty acids present. You must remain still during the
scanning process. Some PET pictures are taken while you are in a quiet resting state.
Others pictures are taken as technicians ask you a series of questions. The questions
may stimulate activity in key memory centers of the brain. They allow doctors to observe
subtle changes in brain functioning more accurately, in some people. The procedure is
painless, aside from the discomfort of an IV injection.

Are there any risks or complications associated with the test?

The procedure is generally safe. However, you will be exposed to radiation during the
scan. Typically, the total amount of radiation is less than that of an x-ray or CT scan of
the chest or ten times the average annual exposure from background radiation. The
amount of radioactive tracer injected is minimal. It is quickly broken down and
eliminated from the body within eight hours, through urination. Increasing your fluid
intake after the scan will help to eliminate the tracing substance.

What are the limitations of the test?
Currently, there are only a small number of PET scanners available in the United
States. They are located at large research centers. The limited availability and high
cost of PET has restricted its use mainly to research purposes.

What is the cost?
The PET scan is more expensive than other scanning techniques. The average cost is
between $1,900 and $3,500. Currently, most insurance companies do not cover PET
scans for dementia patients. However, you should check with your insurance company.

Results

A radiologist specializing in PET scanning will analyze the images and send the results,
along with a written report, to your doctor. It may take a little longer to get PET results
than MRI or CT results. The process of generating and compiling the images is
complicated and requires more time. It is important to remember that brain scans alone
are not enough to make a diagnosis of disease. Other critical components that are
used to diagnose disease include: psychological testing, physical examination and an
assessment of your medical and family history.



Developed by Martha Quinn, Michigan Alzheimer’s Disease Research Center, 2001.
SPECT Brain Scan
What is it?

Single photon emission computed tomography
(SPECT) is a fairly new scanning technique that
shows how the brain functions. More traditional
tests like MRIs and CT scans show the brain’s
anatomy or structure. SPECT scans produce
three-dimensional pictures of how the blood flows in         *Cerebral SPECT Imaging by
the brain. A radioactive tracer is injected. Pictures         VanHeertum & Tikofsky, 1995
are taken as the tracer travels through the bloodstream and into the brain. The scan
produces images that act as a virtual “map” of the brain’s activity. Different patterns of
activity on the “map” correspond with different diseases. Doctors can detect diseased
tissue that would not show up on traditional brain scans, by measuring the rates of
absorption. In general, diseased or damaged brain tissue absorbs the tracer at a slower
rate than healthy tissue. SPECT scanners are available at many large hospitals.

Why is it performed?

SPECT is used to detect internal bleeding, blockage of blood vessels, brain tumors and
epilepsy. For people with symptoms of dementia, SPECT is used to help distinguish
Alzheimer’s disease from other causes of dementia such as vascular dementia,
hydrocephalus, Huntington’s disease, Lewy Body dementia, progressive supranuclear
palsy, Parkinson’s disease, various frontal lobe dementias and dementia associated
with depression. SPECT can by used to identify people at very early stages of the
disease process.

How do you prepare for the procedure?
Usually there are no restrictions of food or fluids before the test or special preparations.
However, your own doctor will provide you with specific instructions on how to prepare
for the scan. When you arrive at the testing site, a technician will escort you to a
changing room and give you a hospital gown to put on. You will be asked to remove
your clothing, jewelry and any other items that may interfere with the scan such as
eyeglasses or dentures. The technician will show you where to store them in a secure
locker or dressing room during the test. After changing your clothes, the technician will
escort you to the examination room. He or she may ask you some brief questions. The
technician will ask you to sign an informed consent form after he or she explains the test
procedure. The consent form must be signed before you start the test.

What should you expect during the procedure?
The test usually lasts between 30 to 45 minutes. A nurse or technician will insert an IV
in your arm to inject the radioactive tracer. The tracer circulates in the bloodstream and
is absorbed by tissues in the brain. After the tracer has been injected, you will be asked

Developed by Martha Quinn, Michigan Alzheimer’s Disease Research Center, 2001.
to lie down on a sliding table. Up to three cameras will circulate around your head,
taking pictures from all angles. You must remain still and quiet during this process, and
refrain from touching your head. The procedure is painless, aside from the mild
discomfort of an IV injection.

Are there any risks or complications associated with the test?
The procedure is very safe. The amount of radioactive material injected is minimal. It is
quickly broken down and eliminated from the body within 48 hours, through urinating.
Increasing your fluid intake after the scan will help to eliminate the tracing substance.

What are the limitations of the test?

The quality of pictures generated by SPECT are not as good as those generated by
more advanced functional scans, like PET. The tracers (also called radio
pharmaceuticals) used by SPECT are also inferior to those used in PET. In many
cases, it is difficult to obtain the amount of data from SPECT scans that is necessary to
diagnose specific diseases. However, SPECT is widely available and is relatively low
cost. For these reasons, SPECT remains the most commonly used brain scan for
viewing how the brain functions.

What is the cost?
The average cost of a SPECT scan is about $1,900. Most insurance companies will
pay for SPECT scans but you should check with your own insurance company to make
sure these types of tests are covered.

Test Results
A radiologist specializing in nuclear medicine will analyze the images and send the
results, along with a written report, to your own doctor. You should expect the results
from your doctor’s office within a few days. It is important to remember that brain scans
alone are not enough to make a diagnosis of disease. Other critical components that
are used to diagnose disease include: psychological testing, physical examination and
an assessment of your medical and family history.




Developed by Martha Quinn, Michigan Alzheimer’s Disease Research Center, 2001.

				
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